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Bird habitat design for people : a landscape ecological approach

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Title:
Bird habitat design for people : a landscape ecological approach
Creator:
Hirschman, Joan
Place of Publication:
Denver, CO
Publisher:
University of Colorado Denver
Publication Date:
Language:
English

Thesis/Dissertation Information

Degree:
Master's ( Master of landscape architecture)
Degree Grantor:
University of Colorado Denver
Degree Divisions:
College of Architecture and Planning, CU Denver
Degree Disciplines:
Landscape architecture
Committee Chair:
Garnham, Harry L.
Committee Members:
Steiner, Frederick
Vitek, Bill
Wiens, John A.

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University of Colorado Denver
Holding Location:
Auraria Library
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Copyright Joan Hirschman. Permission granted to University of Colorado Denver to digitize and display this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.

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Full Text
BIRD HABITAT DESIGN FOR PEOPLE:
A LANDSCAPE ECOLOGICAL APPROACH


BIRD HABITAT DESIGN FOR PEOPLE: A LANDSCAPE ECOLOGICAL APPROACH
Jean Hirschman 3803 Silver Plume Circle Boulder, CO 80303 (303) 499-6441
Abstract
Bird watching is evolving into a sport with mass appeal, according to Time magazine and the U.S. Fish and Wildlife Service. In Colorado, however, the best places to watch birds are under the highest development pressure: watlands and riparian corridors. This thesis advocates developing a bird habitat area in the Denver metropolitan area along the South Platte River because prime habitat for declining bird species is needed as development pressures increase and because watching birds is a source of delight for people. Appropriate tools for designing bird habitat in a human-dominated setting are provided from the science of landscape ecology. A landscape ecological approach encourages designers to evaluate a site in a three-dimensional, dynamic context by looking at its structure, function, and hew it changes. Forms can be generated by applying concepts of spatial and tempera! heterogeneity and the concept that connected areas provide better habitat and recreation potential than isolated areas.
From these concepts, several scales of designs are generated for a 2-mile section of the South Platte River in the vicinity of Brighton, Colorado, an area that will likely be gravel mined for upcoming airport and highway construction projects. To extend the influence of the designed habitat and recreational corridor, designs are generated for adjacent farms and suburbs to demonstrate how providing bird habitat can have practical as well as enjoyable benefits for adjacent landowners. A core park is also designed that includes agricultural, suburban, and wetland demonstration gardens. These gardens incorporate landscape ecological concepts of heterogeneity and connections and are interpreted for visitors so that visitors can use these ideas for their own land. Finally, the impact of this bird habitat area is explored again on the regional scale and scenarios are presented that show how concepts used in the design should be applied on a regional basis.


UNIVERSITY OF COLORADO AT DEVER
A THESIS SUBMITTED TO
THE FACULTY OF THE PROGRAM IN LANDSCAPE ARCHITECTURE AND URBAN DESIGN IN PARTIAL FULFILLMENT OF A MASTER OF LANDSCAPE ARCHITECTURE DEGREE SCHOOL OF ARCHITECTURE AND PLANNING
BY
JOAN HIRSCHMAN
DENVER, COLORADO
MAY 1988
ACCEPTED:
Harry L.
Program Director
Frederick R. Steiner, Chairman ' School of Architecture and Planning, University of Colorado at Denver


ACKNOWLEDGEMENTS
I wish to thank my thesis committee members, Frederick Steiner, Bill Vitek, and John Wiens for providing wisdom and professional guidance as I passed through each phase of this thesis. The fact that the groups 's diverse interests were congenially and constructively brought together in our meetings reflect the fine abilities of the committee members as well as the inherent interdisciplinary nature of the topic selected. If Carl Troll is correct that landscape ecology is a state of mind and that those who approach our environment as a coherent system are landscape ecologists, I v\as fortunate to work with three landscape ecologists.
I am also grateful to coworkers, friends, and fellcw students, especially Patty Sacks, Crystal Gray, and Al Terry for taking the time to listen and help sort out what often seemed like an overwhelming endeavor.
My deepest appreciation goes to David Cooper. His dedication to understanding large-scale patterns of nature and applying this knowledge to many situations has been a major inspiration in creating this thesis.
Plus, it is always great to watch birds with him.


CONTENTS
ACKNOWLEDGEMENTS..........................................................i i
CHAPTER ONE: INTRODUCTION, METHODOLOGY, AND OBJECTIVES..................1
Introduction...........................................................1
Methodology............................................................4
Landscape Ecology and its Relationship to this Thesis.............4
Design Methodology................................................7
Naturalistic Bird Habitat Area Objectives..............................8
Process Sumrary........................................................9
CHAPTER TWO: SITE SELECTION AT THE REGIONAL SCALE - THE BIRD'S EYE VIEW..11
Introduction..........................................................11
Land Classification...................................................11
Region...........................................................11
Landscapes.......................................................12
Applicable Concepts from Landscape Ecology....................19
Spatial Heterogeneity............................................19
Tanporal Heterogeneity...........................................28
Connections......................................................32
Site Criteria.........................................................34
Site Selection Methods................................................34
Identifying Important Habitat Areas within the Region............35
Site Selection...................................................38
Sunmary...............................................................39
CHAPTER THREE: UNDERSTANDING THE SITE AND USERS AT THE LANDSCAPE SCALE...41
Introduction..........................................................41
Site Analysis.........................................................41
Location.........................................................41
Climate..........................................................43
Geology..........................................................43
Hydrology........................................................44
Soils/Gravel Resources...........................................52
Topography.......................................................53
Vegetation.......................................................55
Wildlife.........................................................58
People...........................................................60
Integration of Site Analysis Information..............................65
Site Structure, Function, and Change.....................65
Comparative Landscape Structural Analyses.............................73
Summary...............................................................73


CHAPTER POUR: LANDSCAPE SCALE SITE DESIGN..................................76
Introduction..........................................................76
Design Objectives.....................................................76
Key Users.............................................................77
Birds............................................................77
People...........................................................78
Design Program........................................................79
Bird Habitat Requirements........................................79
Human Requirements...............................................84
Master Plan...........................................................86
General Master Plan Attributes...................................86
Naturalistic Features............................................88
Cultural Features................................................96
Summary..............................................................101
CHAPTER FIVE: LOCAL SCALE SITE DESIGN.....................................109
Introduction.........................................................109
West Bromley Lakes...................................................109
Subdivision Scale...............................................110
Neighborhood Scale..............................................115
Residential Planting Design Scale...............................115
Adjacent Agricultural Land Design....................................118
Veteran's Park/Smith Natural Area Design.............................120
Park Scale......................................................120
Core Park Scale.................................................122
Summary..............................................................125
CHAPTER SIX: DESIGN IMPLICATIONS AT THE REGIONAL SCALE....................126
Introduction.........................................................126
Regional Accomplishments of this Design..............................126
Potential Regional Accomplishments of this Design....................128
Suirmary.............................................................130
CHAPTER SEVEN: CONCLUSION.................................................132
Introduction.........................................................132
Efficacy of Landscape Ecological Methodology.........................132
Other Design Approaches and Future Research Needs....................134
Overall Relationship Between Landscape Ecology and Design............136
SELECTED REFERENCES.......................................................138
PERSONAL COMMUNICATION....................................................144
APPENDIX..................................................................145
Targeted Species' Associated Guilds
FIGURES:
1. Region..................................................................2
2. Process Chart...........................................................9


3. Landscapes............................................................14
4. Nature Preserves......................................................21
5. Heterogenous Habitat Needs - Herons...................................22
6. Patch Shapes - Birds..................................................24
7. Patch Shapes- People..................................................27
8. Heterogenous and Homogenous Plantings.................................29
9. Heterogenous and Homogenous Plantings Over Time.......................31
10. Connections...........................................................33
11. Potential Design Sites................................................37
12. Site..................................................................42
13. Groundwater Contours and Wells........................................46
14. South Platte River Watershed and Tributaries..........................47
15. Floodplain Boundary...................................................48
16. Geologic Cross-sections and Mineral Deposits..........................54
17. Probable Development and Prime Habitat................................63
18. Patches...............................................................68
19. Corridors.............................................................69
20. Matrix................................................................71
21. Existing Prime Habitat................................................80
22. Master Plan...........................................................87
23. Sections..............................................................89
24. Sections - Barr Lake Connections......................................92
25. Spatial Heterogeneity: Shapes........................................103
26. Temporal Heterogeneity...............................................104
27. Connections..........................................................105
28. Proposed Development and Prime Habitat...............................106
29. Prime Habitat and Comparative Development Scenarios..................107
30. Subdivision A........................................................Ill
31. Subdivision B........................................................113
32. Subdivision C........................................................114
33. Neighborhood.........................................................116
34. Residential Planting Plan............................................117
35. Adjacent Farm........................................................119
36. Bird Habitat Park....................................................121
37. Core Park............................................................124
38. Landscapes - Scenario A..............................................129
39. Landscapes - Scenario B..............................................131
TABLES:
1. Precipitation.........................................................43
2. South Platte River Flood Hydrology....................................49
3. Common Wildlife Species in the Study Area.............................59
4. Comparative Descriptive Landscape Structure Models....................74
5. Targeted Species......................................................77


CHAPTER ONE: INTRODUCTION, METHODOLOGY, AND OBJECTIVES
INTRODUCTION
Birdwatching is an increasingly popular form of recreation in Colorado and throughout the United States. According to the Colorado Division of Wildlife (DOW), numbers of birdwatchers are substantially increasing in the Denver iretropolitan area (Hernbrod pers. caim. 1988). At the same time, the number of bird species in this area is fluctuating; sane bird populations, particularly those dependent on wstland and riparian habitat, are declining and because of this, are considered to be "Species of Special Concern" by the DOW and by local experts (DOW 1985, Figgs pers. corm. 1987, Chase pers. canm. 1987). Because of increased development pressures in wetland and riparian areas, it is becoming increasingly important to provide habitat for declining species as well as species of enjoyment to birdwatchers. This is especially true along the South Platte River, the most important riparian habitat and bird migratory route in the Denver area and northeast Colorado.
The South Platte River has beccme a largely industrialized corridor with few remaining natural patches along the 40-mile section from Brighton to Chatfield Dam, south of Denver (figure 1). High-quality gravel deposits within the South Platte floodplain and high local demand for the gravel have resulted in the conversion of much of the riparian/agricultural corridor to a channelized riparian/gravel pit lake corridor. The retaining unmined portions of the South Platte corridor are under additional pressure with the recent advent of a new airport and new highways within the Denver metropolitan region.
1


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After mining, this land is of minimal eooncmic value. Developers cannot sell it for housing, farm it, or industrialize it further. In fact, the remaining steep-sloped lakes are often a liability to landowners after mining as lakes must be fenced and protected from trespassers. This lake-dotted riparian corridor (its scale best appreciated by aerial photographs), if properly designed, could become part of an outstanding system of bird habitats within the Denver metropolitan region, which have great educational potential and are within easy reach of over cne million people.
The term "natural area" when applied to a city or rural area is usually an anomaly. By definition, "natural" means "not artificial or man-made"
(Morris 1976, p. 875). Often the so-called natural area is a completely isolated remnant patch of older vegetation that no longer has natural functions, such as harboring high species diversity and slowing nutrient runoff (Forman and Godron 1986). Or the area is highly modified but unbuildable, such as a gravel pit, that can be recreated into a "natural" (meaning green but perhaps green with native grasses and shrubs instead of bluegrass) area. City natural areas are usually physically separated from the surrounding urban area by fences and by their massages. If used for education, interpretive themes are often slap-on-the-wrist messages that revolve around the dreadful impact humans have had on the environment. Lagging monetary support for many nature centers may indicate that this approach is not working effectively.
To reduce the contrast, more creative integration needs to occur between natural areas and surrounding ccrnmunities. Instead of reducing contrast by creating more suburbs and fewer natural areas, the trend should be reversed and the influence of these natural areas extended more into and through adjacent urban, suburban, and/or agricultural lands. Perhaps a
3


cross between "naturalistic" areas (a more accurate term, implying areas created that resemble nature) and the surrounding community should be encouraged so that homes serve to extend the functions, such as bird habitat, of the naturalistic area. This could result in the formation of a greater constituency for bird habitat protection, since bird-watching areas would be more accessible, and could also result in the formation of more connected habitat areas that better fulfill the functions of larger preserved areas.
This thesis has two purposes. The first is to advocate improving habitat for declining resident and migratory birds in the Denver metropolitan area, since himan development is causing the decline of species dependent on riparian and wetland areas, and because watching birds and being involved in their varied landscapes is a source of delight for many people. The second purpose is to evaluate the effectiveness of applying landscape ecology to site analysis and design of a hybrid between local canmunities and natural bird habitat areas, referred to in this thesis as a "naturalistic bird habitat area."
METHODOLOGY
Landscape ecology is presumed to be an appropriate tool for designing a naturalistic bird habitat area because it emphasizes connectivity between sites with different land uses. In this section, landscape ecology is described in relationship to ecology and design. Based on this brief summary, a design methodology is presented.
LANDSCAPE ECOLOGY AND ITS RELATIONSHIP TO THIS THESIS
Landscape ecology is a recently-emerging field in Europe and the United States that snphasizes study of the landscape, a focus that implies a
4


certain large scale as well as a holistic approach (Golley 1987). By definition, "landscape ecology explores how a heterogenous combination of ecosystems (woods, meadows, villages, etc.) is structured, functions, and changes" (Forman and Godron 1986). The present (although not historical) tendency in ecology is to study individual species or communities in pristine environments where human-induced variables are reduced to the greatest extent possible (Goldsmith 1985). As ecologist Richard Forman stated, "Ninety percent of ecological studies were taking place in two percent of the landscape" (Forman pers. canm. 1987). Landscape ecologists study landscape-level spatial patterns (best appreciated on aerial photographs), the interconnections between these patterns, and the effects of or from these interconnections over time, within a continuum of land use types ranging frcm pristine to urban lands. Because of the focus on a landscape's spatial qualities and the realistic tendency to study interactions within and between human-affected landscapes, landscape ecology is growing with the collaboration of many disciplines, especially landscape architecture.
What, then, is the difference between ecology and landscape ecology as applied to design? McHarg's classic design system (1969) has been labelled ecological design because it is based on "a presumption for nature" (McHarg 1969, p. 12). Consistent and thorough resource consideration is the key to making sound design decisions, according to Design With Nature and this approach has been widely incorporated into planning and design processes around the world. As the method of ccmpiling and overlaying resource data layers was incorporated into design processes, it has become distilled into a method that primarily considers existing resource conditions, and not the spatial and/or temporal qualities of the site resources. This distilled version is the approach most often referred to as ecological design.
5


Ecological design critics recognize that the approach is sensitive to ecological processes, but does not fully incorporate resident and user input in the design process and results in "the sacrifice of cherished and legitimate values, the simple pleasure taken in creating or experiencing compositions that please the eye" and perpetuating monotony (Howett 1987, p. 7).
Landscape ecological design, by addressing the spatial and temporal qualities of settings that are inevitably shaped by social, cultural, and economic factors, is distinctly different frcm this distilled ecological design approach, and nay be more appealing to critics of ecological design. By sane definitions, ecological design and landscape ecological design are synonymous. According to Koh (1982), ecological design:
"...is more inclusive than energy-conscious design. Its conception of the environment is at once physical, biological, cultural, and psychological. The energy-efficiency of an environmental structure and the protection of the human environment are here considered as interrelated and mutually complementary outcomes of the ecological and evolutionary fit between the built structure and its natural and cultural environment"
(p.79).
In this thesis, a landscape ecological approach is taken to select, analyze, design, and interpret a site for use by people and birds because the approach provides concepts that are useful to a landscape architect at a variety of design scales. These concepts, explained in more detail in following chapters, focus on understanding the structure, function, and dynamic qualities of an area, from a regional scale down to a backyard scale. Other useful concepts that can be applied frcm landscape ecology include designing for long term spatial and temporal heterogeneity and designing linkages to important habitat areas. The hypothesized benefits from using a landscape ecological approach in this thesis are: 1) the approach will serve as a useful evaluative tool that enables the designer to
6


classify and inventory the landscape in a synthetic way that considers structure, function, and change over time (Forman and Godron 1986, Hall 1988); 2) the approach will be an appropriate design development tool that provides a basis for generating forms based on concepts of spatial and temporal heterogeneity and interconnections; and 3) this relatively new field will be applied to design in a unique vay not tested before, with results contributing to both fields of landscape architecture and landscape ecology.
DESIGN METHODOLOGY
Naturalistic bird habitat area design involves six stages. First, a regional approach is taken that analyzes the Denver metropolitan area, especially the South Platte River corridor between Brighton to the north and Chatfield Dam to the south, a distance of 40 miles. Landscape ecological concepts, primarily from Forman and Godron's text (Landscape Ecology 1986), are used as a framework. These concepts of spatial and temporal heterogeneity and interconnections between similar areas are used in all stages of this thesis and will be described later. Site selection criteria are then established for a bird habitat area. Finally, using aerial photographs and visiting different sites, an area is selected that meets these criteria.
In the second stage, the selected site is analyzed first through a resource layer approach. This information is then integrated in terms of how the site: 1) is structured, using aerial photographs to recognize repeated structural patterns such as corridors, patches, and the matrix (terminology is defined in chapter three); 2) functions, including movement of species, nutrients, and energy from one landscape to another; and 3) changes, noting the dynamic qualities of the site in its human-dcminated setting.
7


Third, site design objectives are formulated, key users identified, and a design program developed that incorporates bird habitat and human requirements. The site is then designed at a master plan scale, emphasizing use by people and targeted birds, connections to other areas to extend the influence of the design, and long-term sustainability of the design.
Local-scale design is the fourth stage that demonstrates that concepts can be telescoped dcwn from the regional scale to a residential planting design scale. Adjacent suburbs, farms, and a park are designed to show specific connections beyond the bird habitat area.
The influence of the design is then applied back to the regional scale in the fifth stage to demonstrate the achieved impacts of the design on a larger scale, and to explore potential future repercussions of the design. Finally, the overall effectiveness of using principles of landscape ecology in bird habitat design is evaluated. Figure 2 sunmarizes the methodology used in this thesis.
NATURALISTIC BIRD HABITAT AREA OBJECTIVES
Objectives for this naturalistic bird habitat area are:
1) To play a role in providing bird habitat for declining resident and
migratory birds (as defined by DOW and local experts) on a regional and local scale;
2) To be responsive to changing land-use patterns along the South Platte-
River;
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3) To extend the influence of habitat provision to communities beyond
site boundaries; and
4) To balance people's non-consumptive, passive recreation needs with
the sometimes-conflicting habitat needs of a variety of birds.
10


CHAPTER 1VIO: SITE SELECTION AT THE REGIONAL SCALE - THE BIRD'S EYE VIEW
INTRODUCTION
The classification concepts of region, landscape, and landscape elements set the stage for discussing three concepts that provide design guidance throughout this thesis: the positive effects of spatial heterogeneity, temporal heterogeneity, and interconnections. The concepts are then used in defining criteria for selecting a site for the naturalistic bird habitat area and then the site itself.
LAND CLASSIFICATION
The five-county Denver metropolitan area was selected for this thesis because of its growing population of birdwatchers, its increasing urbanization, and the value of wetlands and riparian areas in this semi-arid region. The Denver metropolitan area was further narrowed down to the South Platte River corridor between Chatfield Reservoir to the south and Brighton to the north because of the importance of the South Platte River for migration and bird habitat. These two endpoints to the study area signal the limits of suburban Denver extents at present. Following the river in either direction away from the urban area will bring a traveller to rural surroundings, although the rural flavor of these areas may soon change.
REGION
A region is defined by Steiner et al. (1981), as "an uninterrupted area possessing sane kind of homogeneity at its core, but lacking clearly defined limits." Lyle (1985) acknowledges the planning region, defined by the
11


geographic extent of issues considered. The region considered in this thesis incorporates both definitions and was selected by the extent of relatively homogenous urbanization in a north-south direction (from Chatfield Reservoir to the south and Brighton to the north), by the mountain front to the west, and east Aurora to the east (figure 1).
This is also the area studied by regional transportation planners for the ring-type transportation system new under construction for the Denver metropolitan area (DRCOG 1987) as well as the region studied by Denver City Planner De Boer (1965). According to Forman and Godron (1986), a region almost always contains a number of landscapes; the region considered in this thesis has this characteristic as well (figure 3).
Information at a regional scale is plentiful and has been provided in more detail in the Regional Transportation Ecological Planning Study (Development Research Associates, Inc. and Wallace, McHarg, Roberts and Todd Inc. 1972), and in "Major Drainageway Planning Documents: Phases A and B" by the Urban Drainage Flood Control District (UDPCD 1984). Natural and cultural resource information from these documents will be woven into site analysis information presented in Chapter Three.
LANDSCAPES
A landscape is a "heterogenous land area ccmposed of a cluster of interacting ecosystems which is repeated in similar form throughout its kilemeters-wide extent" (Forman and Godron 1986, p. 31). Landscapes may vary in size from hundreds of miles, such as an agricultural area in eastern Colorado, dewn to a few miles in diameter, such as a snail city surrounded by agriculture, like Brighton, Colorado.
12


Landscapes can be identified on aerial photos, usually by vegetation structure, where there are distinct and measurable changes. J. B.
Jackson, an historian whose exploration of landscapes emphasizes how our surroundings reflect our culture, also recognizes the aerial aspects of landscape analysis. He requested articles for his journal Landscape to be accanpanied by aerial photos because, according to Jackson: "It is from the air that the true relationship between the natural and the human landscape is first clearly revealed" (Meinig 1979, p. 197).
Landscapes are formed by three mechanisms operating within a landscape boundary: gecmorphological processes taking place over a long time (weathering of bedrock, changing river patterns, etc.), colonization patterns of species (including people), and local disturbances to individual ecosystems over a shorter period of time, such as flood impacts from the South Platte River. In sum, a landscape is a distinct, measurable unit defined by recognizable and spatially-repetitive clusters of interacting ecosystems, with similar geomorphological processes and disturbance regimes. A region has a less visible boundary than a landscape does.
Landscape ecology also recognizes the critical role humans play in determining how landscapes are structured, function, and change. All characteristics of a modern landscape, by landscape ecological definitions, are determined by social, political and economic factors. J.B. Jackson further emphasizes that:
"Landscape is not scenery, it is not a political unit; it is really no more than a collection, a system of man-made spaces on the surface of the earth. Whatever its shape or size it is never simply a natural space, a feature of the natural environment; it is always artificial, always synthetic, always subject to sudden or unpredictable change. We create them and need them because every landscape is where we establish our cwn human organization of space and time...A landscape is where we speed up or retard or divert the cosmic program and impose our cwn" (1984, p. 156).
13


Several types of landscapes occur in the region selected for this thesis (figure 3). These include urban/suburban, industrial, and agricultural. Geanorphological processes (e.g. erosion and deposition) are similar among these three landscapes, but colonization patterns and disturbance regimes are different. Each landscape is described in terms of its colonization patterns and disturbance regime, which affect the structure, the functions that take place, such as water, nutrient, and species flow, and changes over time.
Urban/Suburban Landscape
The urban/suburban landscape along the South Platte has been colonized over a 100-year period by humans in a regular manner. Land use is dominated by housing and office units and few natural remnants remain within this region. Once a natural landscape is urbanized, the process is generally one-directional; the landscape remains urban and generally does not return to a natural condition over time. Transportation and information systems are numerous, and species diversity is extremely low, except in park-like settings such as back yards, cemeteries, and golf courses, where planted species are varied and generally non-native. Resident bird communities are depauperate in the urban/suburban landscape in comparison to a natural landscape, but density is high due to the dominance of house sparrows and starlings (DeGraff 1975). Domestic pets, collisions with buildings with reflective glass, and highway mortality are cannon threats to birds in urban environments (Banks 1979).
Drainage from urban/suburban landscapes is usually subsurface in storm sewers until channelized streams are reached. Vfetlands can occur in poorly drained areas, along drainage svoales, and in undeveloped properties where drainage is not designed.
14




Industrial Landscape
Urban/suburban and industrial landscapes along the South Platte River are grouped separately because of differences in colonizational and disturbance regimes. The industrial corridor in the selected region is canprised primarily of gravel mining operations, sewage treatment facilities, a meat packing plant, and other industrial complexes adjacent to the river. The gravel mine-dcminated landscape was colonized once by humans for gravel extraction, and then reclaimed to a more "natural" landscape following mining. Disturbance is two-directional as natural remnant patches are mined and then reclaimed as required by law. Large lakes dominate portions of the industrial landscape, with 100-400-foot-wide strips dividing lakes in many places (a 100-foot buffer must be maintained between a gravel pit and the river or other lakes if the bank is protected with riprap or similar materials. If there is no bank protection, the corridor must be 400-feet wide) (Wright Water Engineers, Inc. 1985, Gray pers. ccmm. 1988).
Gravel extraction along the South Platte River has resulted in widespread destruction of riparian and wstland habitat, but, along with dam construction, also created bodies of water for wintering waterfowl use. Catchpole (1975) emphasizes that the value of gravel pits as potential conservation areas for breeding bird communities in proximity to rapidly-expanding urban environments is high. Many gravel pits along the South Platte were excavated without regard to providing a variety of wetland and terrestrial habitat. As a result, they provide little wildlife habitat, due to 1:1 sideslopes that are highly erosive and cannot support plants, and general oligotrophic conditions. Future reclamation of proposed pits maybe subject to more stringent regulation, and these pits may serve as better habitat buffers against adverse urbanization factors operating in
16


surrounding urban-agricultural landscapes (Wright Water Engineers, Inc.
1985). Pew wetlands are present in developed industrial areas.
The visual character of the industrial landscape varies according to the particular industry. Typically, gravel mining provides open vistas that are interrupted by vertical stockpiles, fences, and mining equipment. The contrast between adjacent urban/suburban landscapes is great, but the gravel lakes are consistent in visual quality with the flat, open agricultural fields, and provide an open contrast to the density of urban and suburban development.
Agricultural Landscape
The agricultural landscape (including grazed lands) along the South Platte is characterized by much lower human density than the urban/suburban landscape and is roughly equivalent in human density to the industrial landscape. Agricultural colonization patterns by humans are of shorter term than either of the two previously described landscapes. Land along the South Platte has changed from natural, to agricultural, and then to urban/suburban or industrial. Although not as isolated and patchy as the natural remnants along the South Platte corridor, much of the agricultural landscape my became urban or industrial within the next 50 years.
The disturbance regime in agricultural landscapes differs from the other two landscapes in that open, relatively homogenous monocultures are created and perpetuated through human intervention such as plowing, planting, grazing, irrigating, and spraying. These disturbances occur on a regular basis throughout the landscape. Landscape elements include fields, hedgerows, roads, farmyards, and drainage ditches or swales too wet to plow. Erosion control methods such as growing winter cover crops or minimum tillage are
17


advocated by county soil conservation districts (Baffe pers. canm. 1988).
The visual character of the agricultural landscape within the region is characterized as "functional" as opposed to "picturesque" (Nassauer 1987). This means that the farms tend to be relatively flat, geometrically regular, and rather homogenous areas, with trees and farm buildings providing the vertical accent, rather than setting the pattern. In picturesque landscapes, however, trees, buildings, rolling hills and diverse vegetation set the pattern. Suburban development next to functional farms typically occurs as a linear wall of houses parallelling a main read, emphasizing the contrast between the two landscapes.
The agricultural bird community consists of a small number of abundant and widespread core species, notably starlings, pigeons, and red-wing blackbirds. Rare species are incidentally found in odd patches of suitable habitat. Mixed farming (tillage and grazing) provides the most diverse habitat which supports a greater variety of birds than either type of farming alone (O'Connor 1986). Where only tillage takes place on a farm, habitat diversity can be achieved by alternating two or more crops within the same field, and by increasing the number of intersection points of different crops (Kress 1985). Shelterbelts, particularly when trees and shrubs are combined in wide swaths, provide extremely important habitat for birds in agricultural settings because they provide movement corridors as well as feeding and breeding habitat (Yahner 1983, Forman and Baudry 1984, Forman and Godron 1986, Schroeder 1986).
Wetlands are often located along irrigation ditches where leaks occur and troughs or springs where cattle drink. These are not ploughed and often support breeding bird populations.
18


APPLICABLE CONCEPTS FROM THE FIELD OF LANDSCAPE ECOLOGY
The three following concepts were derived from a number of references in the field of landscape ecology. Some aspects of these concepts, such as the effects of patch shape on animals, are still considered "research frontiers" and require verification, especially in the arid west.
SPATIAL HETEROGENEITY
Spatial heterogeneity can be thought of as a diversity of horizontal and vertical spaces; the emphasis in the field of landscape ecology on spatial heterogeneity is part of what distinguishes it from ecology.
"Much of the broad field of ecology...has focused on the vertical relationships among plants, animals, air, water, and soil within a relatively homogenous spatial unit. In contrast, what makes landscape ecology unique is its focus on the 'horizontal, ' that is, the relationships among spatial units" (Forman and Godron 1986, p. 7).
Spatial heterogeneity is a powerful design tool for the purposes of this thesis because both birds and people respond to it.
Spatial Heterogeneity and Birds
The following discussion describes spatial heterogeneity in terms of horizontal diversity, which includes patch shapes, and vertical diversity.
It has long been known that Canada geese require distinctly different horizontal habitats for different activities: fields for feeding, open water for protection, and shorelines for nesting (MacArthur 1962). Furthermore, vegetation configurations selected by an individual species for breeding purposes are more or less unique to that species (Wiens
19


1969, 1973; Roth 1976 and others). The concept is significant because many nature preserves select homogenous plant community types as areas for protection (see figure 4). Since many species, such as great blue herons for example, require more than one plant community type for survival, bird habitat areas should be heterogenous areas containing different landscape elements that provide for as many of these diverse needs as possible (Noss 1987) (figure 5). An area where several landscapes meet could also provide horizontal habitat diversity, since birds could be close, for example, to agricultural fields for grain and insect food sources, urban/suburban areas for seed from feeders and fruits from ornamental trees and shrubs, and gravel lake areas for fish and invertebrates.
According to the "emerging general principles" of landscape ecology (Forman and Godron 1986, p. 24), spatial heterogeneity is a fundamental cause of species movement. Furthermore, edge species, such as kingfishers, great blue herons, and western grebes, increase in abundance with increased spatial heterogeneity. The potential for more species to coexist in one area also increases with greater spatial heterogeneity.
As conservation biologist Michael Soule summarizes, "Diversity is good"
(Soule 1986). But is it always good for all species? The riparian South Platte River corridor is heme to edge species (species that occur primarily near the perimeter of a patch) rather than interior species, which are more negatively affected by fragmentation of large forested areas. Therefore, large, homogenous areas are not critically needed in this area and a complex of landscape features, rather than a single large patch, seems more critical for birds in this area. Parasitism (where a bird such as the brown-headed cowbird lays eggs in a host nest, leaving the host to raise ccwbird young.at the expense of its own offspring) and predation by pets tend to increase with greater diversity, however, but creating homogenous naturalistic areas
20



HETEro&EKtx>^ NkToee reese&fc.
Figure 4 -


Figure 5 -
fV^HTKT -fieOKX


will not likely reduce potential threats (Wiens pers. canm. 1988).
As mentioned earlier, the study of patch shapes and patterns and how they affect functions such as species flow is an area of special interest to landscape architects because findings have implications for the design of spaces and forms (see figure 6). Vegetation patterns seem to be the major visual clue to which birds respond initially (Weller 1981). Schoener (1971) found that birds flying over a wooded area are more apt to find a long, narrow clearing that is perpendicular to its direction of movement than a round or parallel clearing. Perhaps a similar case is also true in that a perpendicular forested or shrubby area in a grassland or water environment is more noticeable to birds than a parallel area. Thus, a site that features this or similar features described below may be selected by a bird over another site that does not have this or other bird-attracting shapes.
Convergence points where three or more landscape elements intersect nay also concentrate animal species because of the proximity of diverse resources. Convergence points typically, but not always, occur at the tip of a peninsula (Harris and Kangas 1979). Peninsulas may be important concentrators of sane animal species movement, known as the funnel effect (Forman and Godron 1986).
Patches with sculpted edges have far greater animal activity along their perimeter than do patches with "smooth," lineal edges (Forman pers. comm. 1987). The DCW implements this idea as well by requesting that gravel mine reclamation be designed such that shoreline contours are irregular with peninsulas and bays so that there are a variety of places in which wildlife species can feed, hide, and nest (Tuttle Applegate Rindahl, Inc. 1987).
23


SCOLPTBO
Figure 6
f^TCH '=*V*~E£> 3«I3>E>


According to research in progress, Forman (1988) compared the edge of two pinon-juniper patches in New Mexico. The lineal edges showed 3 times as many animal tracks along the edge as the sculpted patch edge. The sculpted edges, however, showed 9 times as much aniiral scat as the smooth-edged patch, but no scat if lobes were larger than 9 meters in width. Forman noted that a smooth edge may function more as a movement corridor for wildlife and may form more of a barrier than a patch with sculpted edges. Generally, a circular patch, with more interior than an ellipse of equal area, has greater species diversity, but functions less as a corridor for movement, has less habitat diversity, and fewer barriers (Forman and Godron 1986). Ring patches, where a belt of vegetation encircles a hole of different vegetation, may result in similar effects as elliptical-shaped patches.
Forman (1988) feels that forms in nature and the processes that create them and result from them can be repeated for desired results in land reclamation and restoration projects. There are many other forms that occur that require further investigation as to their effect on species, nutrient and and energy flow. Until effects are further studied, experimentation with different shapes must take place (Wiens pers. corrm. 1987).
Vertical heterogeneity should also be provided in a bird habitat area. As more layers of habitat occur as a result of vegetation complexity, more niches can be accommodated, and more wildlife species will occur (MacArthur et al. 1962; Wiens 1974; Short 1983). Research by Karr and Roth (1971) indicates that the greatest increase in avian diversity occurred with the addition of shrub and early tree layers, and that added vegetation beyond that point produced diminishing returns. Roth also found that closed-canopy forests are less patchy and support lower bird species diversity than
25


forests with broken canopies (Roth 1976). These specific data can provide assistance to the designer of bird habitat.
Spatial Heterogeneity and People
Many of the landscape ecological concepts described above also apply to human species and are better documented because people can tell a researcher which landscape features are more appealing, and because the field of researchers is widened beyond scientists to include designers, psychologists, philosophers, historians, and so on. From this cadre of experts, this discussion focuses on spatial heterogeneity perspectives from Simonds (1983), Howett (1987), Koh (pers. comm. 1987), Condon (1988), and personal observation.
John Siironds, in his paradigmatic book, Landscape Architecture (1983), links spatial diversity and patch shapes with human responses. He affirms the landscape ecological principle that as heterogeneity increases, species movement increases by noting that spaces with complex enclosures (or patch boundaries) stimulate excitement, diversion, curiosity, surprise, and induced movement. As spatial variety increases, interest increases.
Spatial variety, therefore, is appropriate when designing for birdwatchers, but, as Simonds says, confined, simple spaces induce repose and relaxation. Perhaps these spaces are more appropriately designed for resting areas within the bird habitat area or in adjacent suburbs. A number of these carefully observed responses can be used by designers to achieve enjoyable places. For example, in a very unscientific experiment involving ten people, the author of this paper quizzed cohorts as to the effect certain shapes shown below would have on them if they were entering a building (figure 7). Figure 7a was unanimously chosen as the most welcoming patch
26


~7C
Figure 7 - - 1PBOPU&


shape, and figure 7b was on the whole the most repelling shape.
In a suburban setting, people are attracted to gardens with a variety of vertical layers and distinct horizontal patterns, but as Howett (1987) points out, the conventional way of handling vegetation in a designed landscape differs from the way plants naturally grow; designed landscapes often lack the vertical diversity of natural landscapes, and therefore lack a garden effect (1987) (figure 8). In the U.S., people have grown used to and continually repeat planting patterns such as the belt of junipers around the house with a tree in the middle of the front yard, not because they perceive it as beautiful, but because it is what they are used to (Koh pers. comm. 1987).
The designer must ask again, when does too much diversity have a negative effect? Simonds (1983) writes that illogically complex spaces produce tension and confusion in people. Condon (1988) argues convincingly that spaces that are fragmented by objects are less desireable than volumetric rooms carved from landscapes. Breathing areas are needed that give the eye a chance to rest before taking in more variety, and edges alcng large spaces are important places frcm which people can observe others. These ideas must also be considered when designing heterogenous spaces for people.
TEMPORAL HETEROGENEITY Temporal Heterogeneity and Birds
Heterogeneity must also be provided in a temporal sense so that spatial heterogeneity will be perpetuated. It is tempting to look at the few remaining stands of mature cottonwoods along the South Platte River as top priority candidates for preservation because provide habitat for birds of
28


Figure 8 HCtT9D2X=,Bs4O0S
rv^rnMGs


interest such as bald eagles, hawks, herons, and owls. However, if a protected area does not also support a natural mixture of regenerating trees, trees will either die and perhaps be replaced slowly by other species, or more mature trees will have to be planted to maintain the mixture of species desired in the bird habitat area. Thus, species must be able to regenerate to maintain the preserve in perpetuity (Noss 1987). Methods of achieving temporal heterogeneity without excessive management are to preserve natural disturbance regimes such as fire and flooding.
Temporal Heterogeneity and People
Landscapes that maintain vegetation diversity over time can be more stable, more self-perpetuating, and more representative of natural processes than their even-aged, planted counterparts. Too often the work of landscape architects perpetuates unnatural, static, and idealized planted legacies, such as when urban streets or suburbs are landscaped with even-aged trees. Plagues of honeylocusts are growing old together along city streets. As with the elms along Speer Boulevard in Denver, when one dies, it may be replaced by a much smaller tree, which ruins the cancpy continuity, requires maintenance to replace the noticeably absent trees, and does nothing to preserve the graceful aesthetic effect over time (figure 9). Planting a variety of trees of different ages can achieve long-term visual quality, reduce maintenance needs, and encourage people to appreciate natural processes.
In an article by Baird Callicott (1983), he laments that the evolutionary-ecological aesthetic of nature remains unappreciated by the average person because it cannot be represented or interpreted in art by landscape painters (Howett 1987). Artist Alan Sonfist strives to achieve appreciation for temporal heterogeneity through his work Time Landscape, where he planted
30


Figure 9 '
&&&>=, ptANTTIM&^ OME&. TTMe


different ages and types of species that comprised the original forests of lower Manhattan Island in the heart of densely developed downtown New York City. One observer remarked about Time Landscape, "...it is not one of those unreal projects that has forgotten death" (Howett 1987 p. 7).
According to Howett, "the time has ccme to see this characteristic as a positive asset of such plantings, because it makes more present to our awareness the dessication, death and decay that are part of a natural cycle" (1987, p. 7).
CONNECTIONS Connections and Birds
Is it better to preserve one large area or several smaller areas? "In regional landscape planning, preservation of whole ecosystems vhth a full complement of indigenous genetic diversity is ideal. This demands a complex of both large and small preserves; the conbined strategy will maintain species and ecological processes" (Noss 1983). Vegetated interconnections among natural remnant patches are as important as the size of the patch. A series of smaller preserved areas may encourage the movement of species in an important movement corridor. Thus, stepping stones of habitat for certain species, if carefully located, may be as beneficial, and certainly more economically feasible, as the preservation of large areas (figure 10).
Connections and People
According to Kevin Lynch (1964), imageable cities have a high degree of continuity, distinctive parts, and are clearly interconnected. Furthermore, paths with clear and well-known origins and destinations have strong
32




identities. People like to be connected to other areas, especially for recreation. Regional bike paths allow for a more regional exchange of people, greater mobility, and variety. Christopher Alexander (1977) advises that connectivity is highly desireable for safe children's play areas, for interlocking fingers of farmland and urban land, for shopping areas, and for opportunities to learn in the city. "Experience is rarely static: almost always there is motion involved" and interconnections between areas facilitate motion (Simonds 1983 p. 145).
SITE CRITERIA
Based on the objectives described in chapter one, and concepts described above, the following criteria were developed to be used in selecting the bird habitat area. The site:
1. Most be located along a stream, reservoir, or area of high groundwater to support wetland plants;
2. Mast have the potential to serve as an important link between protected "natural" and recreational areas so that it is accessible to birds and people.
3. Must be large enough to provide areas of spatial and temporal heterogeneity that can be expanded into adjacent land-use areas to increase its influence.
SITE SELECTION METHODS
First, an assumption was made that important bird habitat can be created if species' life requirements are provided. This assumption allows the
34


designer to select a site where the best habitat may not already be provided, but where the potential for providing habitat is high. MacArthur et al. (1962) suggest that a species should be present in a habitat if its patch type(s) (or niche) is present, if other resources in that habitat are adequate, if canpetitive pressure fran other species for all or part of that patch type is lew, and if the patch can be reached by individuals of that species.
Second, information regarding important habitat areas within the selected region and general vicinity was consolidated. The remaining natural patches in the corridor were investigated and connections between the region selected and other protected areas ware noted. Most analysis -was done fran aerial photos and information provided in the South Platte River Major Drainageway Plan (UDFCD 1984). This information was used to select areas meeting criteria described above; sites were visited, and an area selected.
IDENTIFYING IMPORTANT HABITAT AREAS WITHIN THE REGION
Information about bird habitat specific to the designated region is rather sketchy and derived primarily fran conversations with Colorado Division of Wildlife employees and many individuals familiar with birds along the South Platte. The most important habitat areas for resident and migratory birds within the general vicinity are Chatfield Lake/Arboretum and South Platte Park areas at the southern end of the region and Barr Lake, located 3.5 miles east of the river, at the northern end. Over 130 species of birds have been recorded at the Chatfield Arboretum and 297 species recorded at Barr Lake. These areas offer a diverse conbination of grasslands, forest, lakes, and wetlands, and are appealing to many species. Ornithological records are available of the Barr Lake area and nearby South Platte River corridor as early as 1909 (Hersey and Rockwell 1909). Barr
35


Lake State Park currently attracts many birdwatchers because of nesting bald eagles and the heronry located on a peninsula at the reservoir. Other species of enjoyment such as American white pelicans, Swainson's hawks, night herons, and other birds are abundant at the park. Other important nesting, feeding, and resting areas are shown in figure 11. These are important areas because, although they have been affected by grazing or gravel mining, they still have stands of riparian or wetland vegetation.
The South Platte River Major Drainageway Planning effort of 1984 divided the river corridor into eight reaches from Chatfield Lake State Recreation area to Baseline Road in Brighton and provided an inventory of development, parks, recreation, and open space along the corridor. In analyzing these eight reaches for habitat provision, large areas that provide little to no bird habitat became obvious. Along the southern stretches of river, Chatfield Dam State Recreation Area and South Platte Park provide important, fairly consolidated avian habitat. North of South Platte Park through the heavily-urbanized Denver area, however, large wetland/wildlife observation-oriented parks are non-existent. The Adams County Regional Park is the next largest park-like setting to the north, but the nature preserve is just a small portion of this golf course/fairground/campground/equestrian complex.
Areas shewn in figure 11 were selected for investigation because of their relative uniqueness. Dave Macintosh's dairy will likely be the only unmined or unconstructed "natural" patch left along the South Platte River between South Platte Park and Veteran's Park/Smith Natural Area in Brighton, a distance of 35 miles. The dairy is notable for its large cottonwood stands, its natural flooding regime, and it provides good nesting habitat for great horned owls, hawks, and other species (Macintosh, pers. comm.). No hunting is permitted on the dairy.
36


I MILE.


The Smith Natural Area was donated to Brighton by Morgan Smith in the 1970's for use as a wildlife observation area. No gravel mining or hunting can take place on this property. The Smith family also owns property on the west bank of the South Platte and is considering donating this remnant stand of mature cottonwoods to the city as well (Longhurst pers. ccmm. 1988). The natural area is characterized by a few wetland stand types and is adjacent to the McCann Ditch and the east bank of the South Platte River. Within the last three years, the east bank of the South Platte has been stabilized by the addition of sidewalk riprap topped with fill dirt. The adjoining Veteran's Park was originally a landfill and later developed in the 1960's into a rest stop for highway vehicles.
Another significant remnant riparian patch is the area now known as Brcmley Lakes southeast of Brighton (figure 11). Old river meanders, mature and regenerating cottonwood stands, and proximity to Barr Lake and the Smith Natural Area/Veteran's Park area make this an important habitat area, especially for bald eagles that feed on wintering waterfowl along the South Platte River (Lovell pers. canm. 1987). This area will be mined for gravel over the next 20 years, beginning in 1988. Once mining is completed, the land will be reclaimed for wildlife habitat and recreation and managed by the City of Brighton.
SITE SELECTION
With South Platte Park providing important resting, breeding, and wintering habitat along the river to the south of Denver, it became clear that an equivalent area was needed to the north to connect to Barr Lake, Dave Macintosh's remnant habitat patch, and the Adams County Regional Park. DOW recommended that the best site to design bird habitat and a wetland mitigation area would be on an 80-acre area adjacent to Barr Lake (Lovell
38


pers. canm. 1987). The site would buffer the heronry and eagle nest from highway and other development. This site was considered but rejected because much of the tract is already a wetland, and because providing habitat along the South Platte seems more critically needed with pending mining and suburban development than adding to an existing protected area. Linkages from Barr Lake to a bird habitat area in this vicinity alcng the South Platte would be critical to improving habitat in the region.
Dave Macintosh's dairy was also considered. However it was rejected since, according to the owner, this site's preservation as it presently exists is assured by strong family interest in continuing the dairy operation. Adams County also is discussing conservation easements with the family as another option of preserving the patch in perpetuity. The Adams County Regional Park site was not considered further because of its size limitations.
The Brcmley Lakes area is slated to be mined for gravel. Nonetheless, this appeared as the best site choice when connected with the Smith Natural Area/Veteran's Park site, as it has the potential to provide excellent spatial and temporal variety, and important linkages to Barr Lake and other areas could be provided. Thus, it meets all established criteria and provides an opportunity to work with gravel pit designers and adjacent landowners in creating a reclamation plan that would satisfy the goals of the bird habitat area.
SUMMARY
The terms region and landscape have been discussed to define the area considered by this thesis. Three landscape ecological concepts have been described in terms of their applicability to birds and humans and applied in
39


selecting the site. The site selected meets the established criteria of spatial and temporal heterogeneity and the potential for interconnections between natural and recreational areas in the region.
40


CHAPTER THREE: UNDERSTANDING THE SITE AND USERS AT THE LANDSCAPE SCALE
INTRODUCTION
A site analysis must follow site selection before design can proceed. This chapter also explores concepts of landscape ecology as applied to site analysis. First, the site is analyzed in terms of its canponents: geology, hydrology, topography, vegetation, and so on, with much of this information derived fran the UDFCD (1984), except where otherwise noted. Information is then synthesized so that the site can be understood with regard to its structure, function, and dynamics.
SITE ANALYSIS LOCATION
The study area is in western Adams County, Colorado, T1S-R67W, Sections 1, 11, 12, 13, and 14, as shown in figure 12. It is adjacent to the City of Brighton to the east and is 20 miles northeast of Denver. Major geographic features are the South Platte River and the adjacent uplands. Views of Longs Peak and Mount Evans along the Front Range of the Rocky Mountains are evident from the site to the west.
The site is approximately 1000 acres in size and is about 2 miles in length and an average of 1 mile in width. Major street access is 144th Avenue to the south, E. 160th Avenue (Colorado State Highway 7) to the north, Miller Street to the east, and Riverdale Road to the west. The site is bordered by agricultural and industrial landscapes to the north, south, and west, and by urban/suburban landscape to the east.
41


wmjRA^
VETERAN'S PARI
E. 160TH AVENUE
bromle^JKTane
Figure 12


CLIMATE
Local temperature and precipitation data is summarized in table 1:
TABLE 1: PRECIPITATION (SAMPSON AND BARBER 1974)
[Data for temperature and precipitation from Byers, Arapahoe County. Data on snow cover from Stapleton Airfield at Denver)
Temperature Precipitation
Month Average Average 2 years in 10 will have at least 4 days with— 2 years in 10 will have— Average number Average depth
daily maximum daily minimum Maximum temperature equal to or higher than— Minimum temperature equal to or lower than— Average total Less than— More than— of days with snow cover of snow on days with snow cover
January • F. 43 ° F. 14 ° F. 61 • F. -6 Inches 0. 43 Inches 0. 1 Inches 0. 8 8 Inches 2
February 46 18 64 -2 . 47 . 2 . 7 9 3
March 52 23 70 4 . 87 . 4 1. 6 7 3
April May 62 33 79 19 1. 86 . 7 2. 8 3 4
71 42 86 32 2. 54 . 9 3. 7 1 3
June 84 51 96 40 1. 58 . 7 2. 6 0 0
July 91 57 99 50 2. 01 1. 0 3. 2 0 0
August 89 56 98 49 1. 49 . 7 2. 1 0 0
September 80 47 94 35 1. 14 . 2 1. 7 (‘) 4
October 69 36 83 25 . 72 . 1 1. 5 1 2
November 54 23 71 7 . 54 . 2 . 9 5 3
December 46 18 64 2 . 40 . 1 . 6 7 3
Year . 66 35 J 101 3 -14 14. 05 9. 2 18. 3 41 3
1 Less than one-half day.
> Average annual highest temperature. * Average lowest annual temperature.
Most flood events on the South Platte River are due to summer thunderstorm activity. Average annual precipitation is 14 inches. Sunshine occurs 69 percent of the possible hours of sunlight annually. Vegetation along the river corridor slows windspeeds, which primarily occur from the north and west, but generally the area can be very windy in areas where vegetation has been removed. Wind speeds are highest from December through March.
GEOLOGY
The lcwest and oldest layers of rocks in this area are Mesozoic sedimentary rocks, which bend down into the Denver basin. Pierre shale underlying Denver formation sands and gravels comprise the next layers. The upper surface of
43


the Denver formation is new eroded by the South Platte River and tributaries, which have sculpted the hilly Piedmont surface on which Denver sprawls (Chronic 1980). Within the study area, Pierre shale is encountered at a 20-70-foot depth (Tuttle et al. 1986, UDFCD 1985). Gravel deposits overlay the shale.
HYDROLOGY
The hydrology of the South Platte River from Chatfield Dam to Brighton has been reported in many sources, most notably the UDFCD plan (1984). Although understanding the entire system is important to understanding the river segnent between E. 144th Avenue and E. 160th Avenue, this report will sunrrarize or incorporate the other larger-scale studies by reference and concentrate primarily on hydrologic characteristics in the project area vicinity that have an impact on birds and people.
Groundwater
The reach of the South Platte River included in the study area is fed by an alluvial aquifer called the Valley Fill Aquifer. The aquifer is a sand and gravel deposit, varying in depth fran 10 to 30 feet. Groundwater is 2 to 5 feet below existing ground level. This aquifer is the water supply for the City of Brighton, which draws from a series of wells. Nitrate and sulfate levels are high in the Brighton well water due to farm runoff, and occasionally in summer, Brighton has "Water Quality Alerts" where infants and adults are advised to drink bottled water (Tuttle piers, comn. 1988). Brighton is attempting to dilute p>olluted groundwater sources with better quality ditch water, but other approaches, such as filtering water through wetlands, have potential but have not been tried.
The Arapahoe and Laramie-Fox Hills aquifers also underlie the study area and
44


are separated fran the Valley Fill Aquifer by a layer of Pierre shale. Average depth to water table is 5 to 10 feet in these aquifers that are adjacent to the Valley Fill Aquifer. Water table contours and wells in the area are shewn in figure 13. The water table slopes teward the river and downstream.
Gravel mining has had a number of effects on the water table. Where an open, flat pit has been left, the normal downstream slope of the aquifer is disrupted; thus, the pit acts as a water table drain in its upstream area, and as a water table recharge zone in its downstream area. Prior to mining an acre-foot of gravel contained 0.25 acre-feet of water as saturated aquifer. Removing one acre-foot of gravel results in an equal amount of water moving into that space, increasing the amount of water in the gravel-mined floodplain. It is important that wells in the vicinity do not experience drawdown as a result of gravel mining. Wet gravel mining techniques do not result in significant drawdown since water is not removed
Surface Water
For bird habitat design, water quantity and quality are of critical importance and the following data are of interest: overall surface water characteristics; floodplain delineation; high and low flows; historic configuration and the effects of Chatfield Dam on regulating flows; water quality; and sedimentation and erosion.
Overall Surface Water Characteristics and Floodplain Delineation. Figures 14 and 15 provide an overview of the South Platte basin, major tributaries, and the floodplain boundary in the study area. The floodplain in the study area is essentially natural and unchannelized, although sidewalk pieces armor the banks in many locations.
45


TUTTLE APPLEGATE RINDAHL, INQ.
Consultants for Land and Resource Development
Figure 13 ~ GROUNDWATER CONTOURS AND WELLS


in M i It •
Scott
8000 O ___14000
Scott in Pttl
- SXTTH PLATTE- laVEe; WATPeei4EI>
amo •msirrA^e^ c ot*=cp
Figure 14


READY MIXED CONCRETE CO.
BROMLEY LAKES
FLOODPLAIN LOCATION MAP
TUTTLE APPLEGATE RINDAHL, INC
Figure 15 - FLOODPLAIN BOUNDARY


The study area includes part of the McCann Ditch to the east and the Brighton Ditch to the west. The Brighton Ditch diverts irrigation water from the left bank of the South Platte River. A 44.80 cfs flow is the assigned water right as of 1883. Todd Creek flows from the west into the South Platte River. Its 100-year floodplain width is 4080 feet and new development is not permitted within this area (Moore pers. comm. 1988).
A snail gravel pit on the west river bank is currently the only lentic water type in the study area. This pond is roughly 200-feet by 60-feet in size and herons frequently use the pond.
River Flows. High flows during the nesting season can negatively affect birds if flood levels inundate river banks where kingfishers and other riparian species nest. The study area was severely flooded in 1973 by a flow of around 33,000 cfs during the 100-year storm. The recurrence interval of 2-, 10-, 50-, and 100-year floods south and north of the study area are shewn in table 2. Lowest flews occur during late summer and winter before snowmelt and thunderstorm activity and usually affect birds only if fish and invertebrates are impacted by low flows. Kingfishers and herons benefit from lower flows since they prefer shallow-water fishing.
TABLE 2 - SOUTH PLATTE RIVER FLOOD HYDROLOGY (FROM UDFCD 1984)
Discharge (cfs)
Recurrence Interval
Location
D/S Dutch Creek S. Platte @ Littleton D/S Big Dry Creek D/S Little Dry Creek D/S Cherry Creek S. Platte at 19th Ave. U/S Sand Creek D/S Clear Creek D/S First Creek S. Platte @ Henderson Baseline Road
7-Year— XU-Tear
* *
* 3,100
* 4,350
★ 5,750
3,580 9,700
3,580 9,700
3,580 9,700
3,550 13,000
3,550 12,700
3,400 12,300
3,130 11,400
50-Year iUU-year
5,060 6,400
6,170 7,940
9,600 12,600
12,200 16,000
18,000 22,500
18,000 22,400
17,400 21,700
28,600 38,000
27,500 36,000
27,000 35,500
25,500 33,600
* Snowmelt and Dam Releases Predominate
49


Historic Confiquration and the Effects of Chaffield Dam. The South Platte River has been described as "too thick to drink, too thin to farm, too shallow to sail on, too broad to shoot a rifle across" (UCFDC 1984). In its pristine, intermittent state, the channel width varied from 1500 to 2500 feet across, with numerous deep channels (Knopf 1986). The river's depth, sinuosity, and width depended on the sediment loads and water volumes fron its tributaries. Scouring actions frcm uncontrolled flood waters kept channels clear of vegetation. The advent of irrigation and the construction of numerous ditches in the 1880's resulted in a higher water table in adjacent lands, the creation of a permanent flow, and the elimination of many secondary channels. The construction of four water supply reservoirs, three flood control reservoirs, many detention facilities, channelization, and other facilities have permanently altered the natural flow regime of the South Platte River.
Chatfield Dam, completed in 1975, has an effect on the South Platte River. The dam 's primary function is flood control. Releases are regulated so that the flow at the Henderson Gage near Thornton does not exceed 5000 cfs. Average and peak runoff flows are lower than previous natural flews; thus, the cycle of flooding and scouring during high flow periods has been drastically reduced.
Water Quality. In the reach between Burlington Ditch and Brighton, fecal coliform, nitrogen compounds, copper, zinc, and iron concentrations all occasionally and sometimes routinely exceed standards (UDFCD 1984). In addition, the Metropolitan Denver Sewage Disposal District Plant and South Adams County Sewage Treatment Plant effluent releases result in elevated biochemical and chemical oxygen demand rates. Within the 40-mile stretch from Chatfield Dam to Brighton, water quality is poorest in the northernmost stretches due to farm runoff and sewage plant discharges.
50


The nearest upstream point source of pollution to the study site is the South Adams County Sewage Treatment Plant (4 miles from Brcmley Lakes), which discharges approximately 2.4 million gallons/day (MGD) of treated sewage into the river. No permit limitations exist for anmonia or phosphorous. In comparison, the Metropolitan Denver Sewage Disposal Plant (10 miles upstream from Bromley Lakes) discharges 145 MGD into the stream. This plant only recently has been required to limit ammonia discharges and has recently dechlorinated effluent discharges (Woodling pers. comm. 1988, French pers. comm. 1988). Point pollutant sources such as treatment plant effluent introduce higher organic material concentrations, which results in high densities of pollution-tolerant macroinvertebrates such as bloodworms, sludge worms, and nenatodes flourishing instead of cleanwater organisms such as mayflies, caddis flies, and other invertebrates eaten by many birds (UDFCD 1984). The limited food sources likely limits bird species diversity to some extent. Positive fish and invertebrate response resulting from dechlorination has been noted by aquatic ecologists (French pers. comm. 1988).
Non-point source pollution results from sediments, metals, and nutrients introduced into the stream by stormwater runoff. In addition, stormwater impacts sediments on the river bottom. River sediments are chemical sinks or sources for metals and nutrients; these pollutants can be released depending on the velocity and quantity of runoff. Following major storm events, total suspended solids, organic carbcn, nitrogen, phosphorous, fecal coliform bacteria, iron, manganese, lead, and zinc increase substantially in the drainage, obscuring visibility for fishing birds. Sane bird species are susceptible to fertilizers and insecticides that accumulate in their food, which affects their breeding success (USFS 1981).
51


Stream-bank stabilization also affects water quality of the South Platte. Stabilization with riprap and other materials results in less streamside erosion and can be placed to provide habitat previously not available in the channel. However, sedimentation occurs during the construction period and disruption to sediments on the river bottom can result in resuspension of toxic contaminants.
Sedimentation and Erosion. The average river bed slope from the mouth of Clear Creek to Brighton is 9 feet per mile. Downstream from Brighton, the South Platte river is actively eroding its banks and moving laterally, especially at gravel point bars. The river moves freely, resulting in a higher bank where the current is eroding the bank, and a low bank occuring in deposition areas. Average bankful1 depths are 8 and 9 feet. Between 1963 and 1983, the South Platte River has eroded vertically by 4 feet in the Brighton area. Inpacts from erosion include: exposing utility lines, bridge pier scour, caving river banks, erosion of trees and resulting debris, loss of agricultural land, breaching of gravel pits, lowered groundwater tables, and increased channel capacity. Loss of nesting areas and bird habitat also results from erosion.
SOILS/GRAVEL RESOURCES Soils
Pliocene period ground surface elevations in the Brighton area were 1600 feet higher than present and eight cycles of erosion and filling have occurred since then, with a ninth currently in progress (UDPCD 1984). Surficial deposits are characterized by four soil types in the study area (figure 8): loamy alluvial land; moderately wet (Lw); loamy alluvial land, gravelly substratum (Lv); sandy alluvial land (Sm); and wet alluvial land
52


(Wt) (Sampson and Barber 1974). The characteristics of each soil type are summarized and mapped in Sampson and Barber 1974.
A large number of human-made surficial deposits occur in this area, notably the concrete and asphalt pieces along the South Platte banks placed for bank stabi1i zation.
Gravel Resources
Mineral resources along the South Platte River are limited to high quality gravel deposits. The gravel is primarily granite, quartz, and pegmatite. Pebbles and granule gravel constituting about 50 percent of the deposit, and sand about 50 percent. Fines and oversize material generally are lacking. Cross-sections of gravel deposits in the Brighton area were made by Turner (1974). These crossections show that most of the extractable gravel is concentrated on the east side of the river (figure 16).
Gravel deposits have been mined extensively within the Denver metropolitan area, with most remaining deposits occurring in Adams County along the 2-mile-wide river corridor. According to Brighton city planners, except for the Veteran's Park/Smith Nature Reserve, most of the South Platte corridor around Brighton will eventually be mined for gravel (Moore pers. comm. 1987). Records collected in 1984 do not show future mining plans for the area between Brcmley Lakes area and Bridge Road (UDFCD 1984), but the city has been contacted to negotiate with gravel companies for parcels within the study area.
TOPOGRAPHY
The study area is within the Colorado Piedmont section of the Great Plains physiographic province (Sampson and Barber 1974). The area is drained by
53


r-GEOLOGIC CROSS SECTIONS tO G-G'
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the South Platte River system and is characterized by broadly rolling topography and streams in bread valleys. The elevation of the study area ranges from 4970 feet above sea level at the Branley Lake site to 4955 feet at the Smith Nature Reserve. The river bottom is approximately 10-30-feet lower than the adjacent uplands and side slopes are moderately steep.
The river valley in the study area vicinity trends in a northeast/southwest direction, but numerous meanders characterize the valley in this unrestricted section. Most slopes face northwest and southeast, with a few slopes facing east and west. Very few slopes have a direct north or south aspect.
VEGETATION
The vegetation of the South Platte River drainage has changed considerably since the late nineteenth century. Historically, the river was relatively straight, wide, and flowed only 4-6 months during spring and early summer each year (Knopf 1986). Now the river is one-fifth to one-twentieth of its original width. Irrigation agriculture initiated in the 1880's, involved ditch construction and impoundment of spring runoff, resulted in percolation of water through valley alluvium, causing the water table to rise to the point of sustaining a permanent, year-round flow in the river. River banks that were once continually disrupted by the constant shifting of the river channels, became relatively stable, although flooding and scouring regimes still occurred.
Overflow channels such as abandoned meanders and oxbews served as "nursery bars" for hydrophytic species, such as sandbar willows. Willow stands became established since there was a constant water source, and became dense enough that they provided a barrier to floodwaters and reduced water
55


velocities, causing sediment deposition. Cottonwood seedlings were established on these raised bars composed of fine sediments. When they matured, they shaded out the willows, and prevented much seedling regeneration of other species (Brady et al. 1985).
With the advent of flood control dams and stream channelization, overflow channels were no longer formed. Shrub stands were greatly reduced in numbers, and cottonwood regeneration has been restricted. Riparian vegetation is still developing, however, with the spread of introduced species such as Russian Olive and tamarisk.
Four broad categories of vegetation can be identified within the study area: upland cottonwood forest, shrub-herbaceous wetland, agricultural, and grasslands. Within these bread categories, stand-types (sensu Marr 1967) can be designated.
Upland Cottonwood Forest
Cottonwood Stand-Type: Cottonwood stands dominated by plains cottonwood occur along former river meanders and oxbows. These stands are mature, ranging in age from 60 to 100 years (usually the maximum lifespan of this species in this region) and there is little regeneration due to the absence of flooding and scouring regimes needed for seedling regeneration (Brady 1985). These mature stands provide seeds, buds, and twigs for wildlife feeding, as well as important nesting and perching habitat for numerous bird species, ranging from cavity-nesters such as woodpeckers to colonial nesters such as herons. The understory of this stand type is generally limited to grasses, due primarily to grazing impacts.
56


Shrub-Herbaceous Wetland
Cattail Stand-type: Wide sections of the McCann Ditch in the Smith Natural Area/Veterans Park area are dominated by cattails. During Spring 1988, however, it was noticed that large sections of these cattail stands appear to be victims of a muskrat eat-out. If this is the case, muskrats have eaten the tuberous base of the cattails and then built feeding platforms of the leafy remains. Small stands can be wiped out in a single season and muskrats then move on to other areas. The cattails can regenerate quickly from a few remaining tubers if water levels remain stable (Weller 1981). Cattails are obligate wetland species.
Sandbar Willow-Tamarisk Stand-type: Isolated stands of these wetland shrubs are also present in the Veteran's Park/Smith Natural Area and comprise about 90 percent of the total shrub layer in the 1000-acre study area.
Poison Hemlock/ Canadian Thistle Stand-type: The water table is apparantly dropping in sane locations within the Veteran's Park/Smith Natural Area, typically identified by the dense influx of these two herbaceous species adjacent to a wetland (Cooper pers. canm. 1988).
Agricultural
Corn-Soybean Stand-Type: Farmers in the study area currently plant east-west or north-south-oriented crops. Crops are sown in April or May, harvested in late summer, with stubble standing over the winter. Winter cover crops such as winter wheat are sometimes planted. Grains provide a food source for geese and other seed-eating birds, as well as rodents.
Grasslands
Smooth Brome-Timothy Stand-Type: Pasture grasses have been planted in
57


fields throughout the study area to increase species for grazing in the native short-grass prairie ecosystem.
Buffalo Grass-Blue Grama Stand-Type: Some grazed areas are still dominated by these native short grass prairie species.
Barnyard Grass-Ambrosia Stand-Type: Areas that have been scraped, trampled, or compacted due to gravel mining and other types of disturbances are dominated by numerous annual herbaceous species that provide important food and cover for birds and small mammals.
WILDLIFE
Birds
Many bird species on the Barr Lake Bird Species List (n. d.) are likely to occur only rarely along the current configuration of the South Platte River in the study area. However, as gravel pits are created in the future, more of these lentic and wetland species will likely be attracted and therefore species from Barr Lake are considered to be bird species of the study area. Targeted species and their associated guilds (appendix A) have been identified for design purposes and are described in the following chapter under "Key Users." Prime feeding and breeding habitat in the existing study area, the existing proposed development scenario, and the desired development scenario are compared in chapter four.
Mammals, Reptiles, Amphibians, Fish, and Invertebrates
The DOW has identified the following key species present in the study area:
58


TABLE 3: CCMMON WILDLIFE SPECIES IN THE STUDY AREA (TUTTLE APPLEGATE
RINDAHL, INC., 1987, FRENCH PERS. COMM. 1988)
Mule deer
White-tailed deer
Red fox
Raccoon
Skunk
Beaver
Prairie dog
Mice and other small mammals Builsnake
Plains garter snake Ccmmon garter snake
Tiger salamander Painted turtle Northern leopard frog Bullfrog
Woodhouse's toad White sucker Green sunfish Yellow perch Largemouth bass Ccmmon carp Longnose sucker Sand shiner Fathead minnow Mosquito fish Long-nosed dace Brook stickleback Plains killifish
Sludge worms
Bloodworms
Nematodes
With the exception of red fox, mammals generally have adapted well to edge conditions and the increasing influence of humans. Deer are depending more on suburban plantings as food sources than ever before; skunks and raccoons opportunistically feed close to human habitation; and beaver are active in streams close to human habitation, as is the case at the Smith Natural Area. A large prairie dog town is presently located within the study area. Prairie dogs and other snail mammals are important food sources for raptors, eagles, and owls.
59


Many reptiles and amphibians are also food sources for a variety of large birds cannon in the study area, such as eagles, herons, raptors, and owls. Gravel lakes could provide habitat for an even greater diversity of fish, including minncws whose natural habitat is declining due to wetland destruction and stream channelization (Woodling pers. ccmm. 1988). Many bird species feed on invertebrates, although reduced water quality along the South Platte in this section limits the species available for feeding.
French (pers. ccnm. 1988) reports that caddis flies and mayflies could becane numerous along the South Platte again as a result of sewage treatment plants dechlorinating effluent, but additional impacts resulting from proposed channelization would counteract this benefit.
HUMANS
Brief History of the Brighton Area
Historically, Brighton's roots are agricultural. Beginning in the 1880's, early settlers began diverting water from the South Platte and began farming corn and other crops. The canned vegetable industry was sparked by the advent of the railroad in 1908, and is still a major employer in the Brighton area. Farms in the study area were established around 1910.
Existing Uses
People currently utilize the study area for agricultural uses, grazing, horse excercising, junk storage, recreation, and wildlife observation. They travel four major corridors, Riverdale Road to the west, 160th Avenue to the north, E. 144th Avenue to the south and the South Platte River. Adjacent, land uses include housing subdivisions, two cemeteries, horse boarding, a playground, farming and ranching activities, and a sewage treatment plant.
60


Planned Future Development
Major growth factors affecting the region and creating demand for gravel resources are the proposed new Denver metropolitan airport, to be located near Barr Lake, and E-470, a proposed toll road with a planned alignment that would cross about 3 miles south of the study area. New transportation developments such as these result in associated housing and canmercial development. If the new airport is built south of Brighton, a 3 to 6 percent growth is projected for the Brighton area, as opposed to the current 1 percent and under growth rate currently experienced (Moore pers. canm.
1988). A 157-acre planned unit development adjacent to the Bromley Lakes gravel mining operation is scheduled for development within the next 5 to 10 years and will consist of attached and detached single and multi-family residential units and a 10-acre park.
On a larger scale, the Adams County Ccmprehensive Plan (1984) designates future uses of the study area to be floodplain, open space, and recreation. The more specific county objective for the study area is to: "restore the wildlife value of the South Platte River Valley after mining disturbance, and protect that value during subsequent redevelopment" (Adams County Ccmprehensive Plan p. II-5). The resulting policy is to "encourage environmentally sensitive designs for all types of developments that reduce pollution, take advantage ofexisting natural features, and create spaces favorable for wildlife" (Adams County Comprehensive Plan p. II-6).
The Brighton Ccmprehensive Plan is currently in progress and will direct future development in a Kevin Lynch-oriented manner (1960) (see following section).
The South Platte River Recreation Plan (UDFCD 1984) reccnmends that a linear park with regional or focal point parks be developed along the river within
61


the study area. A bike, hike, and maintenance trail with an adjacent horse path would be constructed alcng the west bank, with proposed boat landings and chutes constructed along the west bank. Preserving and enhancing existing wildlife habitat is recommended and creating new vvetlands is also recamiended in abandoned oxbows. A channel engineered to acccmmodate 10-year flood events (riprap and vegetative bank protection) and floodplain management is recamiended to stabilize eroding banks throughout most of the study area and the removal and relocation of the Brighton Ditch diversion dam is also suggested once the river is channelized to the UCFDC (1984) design. Along the west bank of the South Platte River, opposite Veteran's Park, the plan proposes to construct a pocket park with 18-car parking and a boat landing. A pedestrian bridge would be placed to connect the west bank to the Smith Natural Area.
The Bromley Lakes gravel mining plan (Tuttle Applegate Rindahl, Inc.,
1987) involves excavating three 27-foot deep lakes (291 acres of water surface) in two phases, while maintaining the required 100-to 400-foot buffer between the lakes and river. The first phase involves setting up the plant, constructing an access read frem Old Brighton Road, relocating portions of the MzCann Ditch, stripping and stockpiling topsoil, and planting stockpiles to screen the site and prevent erosion. During Phase II, 15 acres per year will be stripped and excavated. Dikes between the lakes will accommodate an existing natural gas line and will be constructed at 3:1 slopes. The life of the mine is expected to be a minimum of 20 years.
Most of the mature cottonwoods in the largest river meander would be preserved. The slope of the lake shoreline would be 3:1 from existing ground level to 10 feet belcw the water surface. A 2:1 slope would be formed below 10 feet of the water surface to the bottom of the pit. Processing and
62


batch plant locations would revert back to cropland according to the plan and three access roads would remain in place. The applicant will reclaim the land "to a state suitable for wildlife habitat" (Tuttle Applegate Rindahl, Inc. 1987). After mining is completed, the City of Brighton will manage the property and use it as a community park. An overlay of probable future development and its relationship to prime bird species habitat is shown in figure 17.
Brighton 's Image
Brighton, to a visitor, is seen as a slower-paced, small agricultural town that, if winds are from the east, greets visitors with a whiff of livestock. To residents, the laissez-faire governmental attitude that allows rugged individualism is appropriate to their needs. However, proposed airport development and subsequent growth may change this image. The potential for increased growth has encouraged community planners to prepare the Brighton Comprehensive Plan and rally the community to identify what they perceive future image to be.
According to the planning coisultant in charge of the plan, the community would like a more designed image in the future (Sayre pers. comm. 1988).
Slow incremental growth will likely be a thing of the past, and Brighton wants to establish a positive, landscape-oriented image for the rapid growth ahead. Planners have invoked Kevin Lynch's Image of the City (1960) to create the desired ambiance. The city is understood in terms of paths, activity centers, and districts, with corresponding scales of development for different element types. Brighton's terminology for structuring the urban landscape is compared to other systems, including landscape ecology's, in table 4.
63


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INTEGRATION OF SITE ANALYSIS INFORMATION
In this section, the previously described site information is integrated so that the structure, functions, and dynamic qualities of the site can be understood. The structure of a landscape can be seen as repeated patterns of patches and corridors within a matrix. Species, nutrients, wind, water and energy flow in characteristic ways between these patches and corridors.
Change also occurs in characteristic ways, as described in application to the project area. Each structural element, followed by a discussion on function and change, is described by using landscape ecological terminology (Fonran and Godron 1986). Landscape ecologists are not alcne in their classification of landscape structure; several approaches from other disciplines are also presented.
SITE STRUCTURE, FUNCTION, AND CHANGE Patches
A patch is a "nonlinear surface area differing in appearance from its surroundings and often imbedded in a matrix" (Forman and Godron 1986, p. 212) Several types of patches have been described in the literature and occur in the study area. Disturbance patches are small areas disturbed in a matrix on a frequent or infrequent basis, such as areas that burn or flood regularly. South Platte River channels shift frequently and the river section in the study area is considered by the UDPCD (1984) to have serious river bank erosion problems. The flood control plan for this section is to line most banks with riprap and vegetation slope protection to prevent flooding from 10-year storm events. This will restrict natural erosion and deposition regimes, and flooding regimes will be controlled by upstream dams. Therefore, disturbance patches resulting from flooding, once
65


characteristic of the entire South Platte floodplain, are increasingly rare and soon may cease to exist.
Remnant patches occur where widespread disturbance isolates a small undisturbed area. Old flood disturbance patches resulting from pre-dam and channelization flows, such as cottonwood forest occurring at river meanders and abandoned oxbows, are evident throughout the river corridor. These can now be considered as remnant patches since they are not being replenished.
In fact, as the area sustains more gravel mining, these patches will beccme even more isolated and rare. Remnant patches, such as these cottonwood stands, often provide important wildlife habitat in an urban setting, and connecting these patches is important in reducing their isolation. The Smith Natural Area also is a remnant patch, embedded in a matrix of agricultural and industrial disturbance.
Introduced patches are created when organisms are introduced into an area. Introduced species often exert a dominating and continued effect and are the most widespread patches on earth. Most of the site is ccmprised of introduced patches. These are the agricultural fields, the bluegrass lawn of Veteran's Park, and the surrounding hemes and ranches. They are characterized by introduced species, such as cats, hybridized com, and bluegrass, as well as by inmigrating native species, such as starlings flocking at a farm or mice moving into hares for the winter. These patches characteristically require the use of fossil fuels to maintain them in a continually disturbed state than other patches.
As described in chapter two, patch shape and size are critical, to
understanding the function of the site. Previously mentioned
research by Schoener (1971), indicates that animals are attracted to forms
66


that flow perpendicular to a travel course. Some of the cottonwood-forested meanders that are perpendicular to the river should be preserved for those reasons. Convergence lines occur at shelterbelt/ditch/ field intersections that may also concentrate animal occurrence (Forman and Godron 1986). Important patches for bird habitat are summarized in figure 18.
Corridors
Corridors are narrow strips of land which differ from the matrix on either side. Stream corridors border water courses and vary in width and gradient. Line corridors are narrow bands, such as hedgerows, paths, and drainage ditches, dominated throughout by edge species.
The daninant stream corridor in the study area is the South Platte River corridor (figure 19). It is curvalinear (before channel stabilization). Breaks in the continuity of the riparian vegetation-bordered corridor occur where fields and debris dominate the banks. The stream corridor functions as a conduit for water and nutrient flow, animal movement flow (for wildlife as well as recreationists), and seed dispersal agent. It also functions as a barrier to smaller mammals. As mentioned earlier, its dynamic qualities are being reduced by channelization.
Line corridors include the McCann and Brighton Ditches, Riverdale Road, E. 160th Avenue, numerous farm roads and property boundaries, powerlines, two hedgerows, and two distinct cottonwood-lined abandoned river meanders, which essentially form a curvalinear hedgerow.
The two hedgerows were planted along field edges to block winds, and are characterized by low species diversity and relative homogeneity in horizontal and vertical structure. Hedgerows serve important functions in the pasture/agricultural setting. They provide access for two out of three
67


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lowland terrestrial birds and mammals to food in adjacent fields, as well as provide shelter from predators (Forman and Godron 1986). Hedgerows also reduce the eroding effects of winds, and create a cooler, more humid microclimate on the leeward side. Evapotranspiration is greater than from the adjacent fields, but reflection of light is reduced in hedgerows (Ftyszkcwski and Kedziora 1987). Avian diversity is relatively high in hedgerows for feeding and breeding and hedgerows are of critical importance in a landscape with few woods, since forest species may be limited only to hedgerows. Connecting forest patches, such as riparian forest growing along the South Platte, with the two hedgerows may serve to increase critical wildlife habitat for forest species in the study area.
Matrices
A matrix is the most extensive and connected part of a landscape. It can be seen as the cement that surrounds independent elements, such as patches and corridors, with the area of the matrix exceeding the total area of any other : landscape elanent type present. Three characteristics of a matrix are: relative area occupied by each landscape element types, the level of connectivity present between landscape elements, and the degree of control over landscape dynamics.
In the study area, the highly modified agricultural fields are the matrix in which disturbance and remnant patches and stream and line corridors are imbedded (figure 20). However, according to plans and predictions, this will change in the next 50 years as the matrix in the study area becones gravel pit lakes.
The stream corridor will remain, but line corridors will be dominated not by hedgerows and river meanders but by the 100-to-400-foot- wide mandatory buffer between the river and the lake, and by pipeline corridors that separate gravel pit lakes. Thus, the gravel pit lakes will comprise a large area and
70




will be the most connected landscape. Since natural succession will be thwarted by the deep, groundwater-filled lakes and lack of flooding, the matrix will exert a greater degree of control over landscape dynamics than the previous agricultural landscape or even a natural landscape. This is a critical point. Because the gravel pits are unsuitable for agricultural, urban, or suburban development, they could became abandoned areas in the middle of expanding urban land. Yet they have the potential for serving as rich wildlife habitat or as a water-oriented recreation resource in an arid environment. If gravel pits will become the future matrix, they must be designed so that they will serve a useful future purpose.
Understanding patches, corridors, and matrices, hew they function and change, is a way of seeing the landscape in a horizontal way, as if looking at a landscape from an airplane or as a bird looking for shelter. Many questions about horizontal configurations are still unresearched; for example, what is the optimal width of a corridor for providing shelter and connecting remnant patches? What is the preferred distance between natural remnant patches for migrating birds? Is it better to have a number of tiny stepping-stone patches in a human-disturbed migration route, or a variety of patch sizes and shapes? Perhaps creating corridors as tendrils will encourage species into a particular area where people can watch. Research is only beginning on these subjects and although it is known that same species require heterogenous landscapes to satisfy habitat requirements, it is unknown how large a patch should be, or hew wide a strip corridor is preferred by certain species, or how close one landscape element should be to another. Again, experimentation is the suggested route at this stage of the field.
72


CUMFAKAT1 VE LANDSCAPE STRUCTURAL ANALYSES
Steinitz (1988) first canpared descriptive mcdels for landscape structural analysis from Lynch (1960), typical geographic information systems, and landscape ecology. Additional models by Alexander (1977) and the City of Brighton are added to show that landscape ecologists have not invented a new approach to understanding landscape structure, rather they confirm in ecological terms the repeated patterns that others have already discerned (table 4). With the exception of Alexander, whose remarkable work specifically gives pattern guidance at each descending scale, the terms used in these structural analyses are applicable at all scales. Landscape ecology tends to focus on landscape-level patterns perceived frcm aerial photos, but these patterns are scale-independent (Forman and Godron 1986).
SUMMARY
This chapter focuses on existing site conditions by analyzing environmental components individually and then integrating this information by using landscape ecological concepts of structure, function, and change.
Thinking in terms of patches, corridors, and the matrix can help the designer understand the spatial qualities of a place, much like Kevin Lynch's examination of cities in terms of nodes, paths, and districts (1960). Understanding how a patch or corridor functions with regard to species flew, energy, and nutrient exchange can help a designer predict the effect of a design. For example, different patch shapes have different effects on animal activities. By understanding these effects, designers can use patch shapes in habitat restoration situations to concentrate or disperse species. By understanding the microclimate and habitat functions of hedgerows, for example, designers can effectively use
73


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them in desireable situations, such as along the north edge of an agricultural field that connects to a stream corridor. Likewise, hedgerows would not be used in undesireable locations, such as where snow blocked by the hedgerow will bury access routes. Specific applications of these concepts are shown in the following three chapters.
75


CHAPTER FOUR: SITE DESIGN
INTRODUCTION
This chapter sets design objectives, identifies key site users and their basic requirements, and designs the site according to information and concepts described in the previous chapters. The emphasis of the design is on reclaiming the mined site as an example for future gravel pits and creating connections between the gravel-mined area and adjacent suburbs, agricultural areas, and wildlife areas.
DESIGN OBJECTIVES
Design objectives originate from the overall site objectives discussed in chapter one and are further defined by emphases of landscape ecology on spatial and temporal heterogeneity and linkages discussed in chapters two and three. Objectives will be met through site design and through emphasizing coordination with adjacent property owners. Five objectives are:
1. Connect important patches with corridors to provide linkages within the site and to connect it with other important habitat areas in the region;
2. Utilize research on patch shapes to create rich, varied areas for high bird species diversity and to create interesting spaces for people to enjoy;
3. Increase quality and quantity of habitat for targeted bird species, their associated guilds, and watchable birds in general;
4. Design a sequence of plantings so that patch configurations, corridors, and wildlife habitat for targeted species and guilds can be maintained over the long and short terms; and
76


5. Design areas that are enjoyable and educational for visitors and adjacent residents. Do this in a manner that creates a balance between bird habitat requirements and people's environmental and socio-economic needs.
KEY USERS BIRDS
Although a goal of the design is to create habitat diversity to attract as many bird species as possible, it would be impractical to design for each of the 300 or more species that presently or potentially could use the site. Based on discussions with local ornithologists and review of DOW's Species of Special Concern list (1985) and other literature, the design will consider the habitat requirements of six bird species for the reasons shown in table 5.
TABLE 5: TARGETED SPECIES
Species Name: Great Blue Heron
Belted Kingfisher
Reasons For Selection
Very sensitive to disturbance (Vos 1984); high-profile bird with public which enhances preservation interest (DOW 1985); data available (Short 1985)
Species of enjoyment; data available (Prose 1985)
Western Grebe
Lewis' Woodpecker
Declining species; nesting negatively affected by fluctuating water levels in artificial water bodies (DCW 1985); data available (Short 1984)
Population decline due to competition with starlings and habitat destruction (loss of snags) (DCW 1985, Figgs, pers. canm. 1987)); data available (Sousa 1983)
77


Canmon Yellowthroat
Population decline due to marsh drainage (DOW 1985)
Yellow Warbler Population decline due to heavy
Brown-headed Cowbird parasitism (DOW 1985); data available (Schroeder 1982)
The targeted species represent a range of species using different types of habitat in a riparian ecosystem. In providing habitat for these birds, many other birds with similar feeding and breeding requirements will also be accommodated. These aggregates of species are known as guilds (Short 1983, Short in press). According to estimates, if the following conditions described earlier are met: habitat for species is present, competitive pressures are lew, and a colonizing source is present (Roth 1976), then approximately 180 species comprising guilds for targeted species would likely utilize the area, as well as other birds migrating along the South Platte corridor and in the Barr Lake vicinity.
Designing for these six species may not provide enough habitat diversity to attract seme upland bird species or winter residents. To meet the objectives of attracting high bird species diversity for people's enjoyment, those non-specific birds that could generally be attracted to diverse suburban gardens or agricultural areas are also considered as targeted species.
PEOPLE
The following user groups would be expected to use this study area over a 50+-year timeframe:
Birdwatchers
School children and teachers
Recreationists (rafters, canoers, joggers, swimmers, sailboarders, bicyclists)
Families
78


Local teenagers Senior citizen groups Mining canpanies Farmers
DESIGN PROGRAM
BIRD HABITAT REQUIREMENTS
In this section, prime habitat needs for targeted species will be summarized as they are pertinent to future study area design. The U.S Fish and Wildlife Service Habitat Evaluation Procedures Group has synthesized biological and habitat information published in the scientific literature as well as unpublished information reflecting the opinions of experts on five of the six targeted species. These sources (Schroeder 1982, Sousa 1983, Short 1984, Short 1985, and Prose 1985) and others (Stokes 1979, Hancock 1984, Vos 1984) should be referenced for further detail. Existing prime habitat for targeted species is shown in figure 21.
Great Blue Heron
This species is commonly seen in marshes, reservoirs, and streams. Shallow areas are needed for feeding and tall deciduous trees near water are preferred as colonial nest sites. These birds are sensitive to human disturbance, particularly mechanical disturbances entailing large machinery operation.
Prime breeding and feeding habitat is comprised of the following elements (Short 1985): 1) Active or potential nest site is at least 0.6 acres in area, located within 825 feet of water, with nesting trees at least 15 feet high with sturdy branches capable of supporting nests. Trees may be alive
79




or dead but must be open enough to allow herons to freely enter and leave nests; 2) a disturbance-free buffer zone during the breeding season, February through August, of 825 feet over land or 500 feet over water occurs around actual or potential nest sites; 3) distance between potential and existing heronries should be less than 0.62 mile; 4) foraging habitat is a water body that contains small fish, shallow water less than 1 to 2 feet deep, and a firm substrate; 5) a disturbance-free zone up to 300 feet occurs around potential foraging areas; and 6) the foraging area is free from human disturbance for at least 4 hours per day (4 hours following sunrise or preceeding sunset).
Belted Kingfisher
The belted kingfisher is a bird of stream courses, lakes, and ponds which feed primarily on fish, which they catch in clear, shallow waters that are not overgrown with thick vegetation. Nests are excavated in vertical cutbanks of relatively friable soils.
Prime breeding and feeding habitat is comprised of the following elements (Prose 1985): 1) a miniitum habitat area is within 3500 feet from the edge
of a water body; 2) perches should be 200 feet from the water's edge and located in an area where the water is less than 2 feet deep and between 30 and 70 percent riffles; 3) one suitable perch should be evenly spaced and located every 80 feet; 4) the top 6 inches of water, where most fish are caught, must be relatively clear; and 5) there must be suitable, friable soil for burrow excavation (70-96 percent sand and less than 15 percent clay). Thus, the design for belted kingfishers would strive to place evenly-spaced perches within 200 feet of the river or gravel lakes, where the river has between 30 and 70 percent riffles and the water is less than 2 feet deep. Gravel pit banks are conmonly used nest sites (Bull 1974) and additional nesting habitat would not need to be provided.
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Western Grebe
This species prefers to feed and breed on large marshes or reservoirs with large supplies of small fish. They nest on the water surface layer and feed within the water surface and water column layers.
Prime breeding and feeding habitat are comprised of the following elements (Short 1984): 1) a wetland/reservoir greater than 50 acres; 2) the presence of small fish populations; 3) sheltered coves with herbaceous wetland vegetation adjacent to open water (70 percent of the water body should be free of vegetation, within the 30 percent of the water body that sustains wetland vegetation, wetland plants should be interspersed with open water as much as possible); 4) vegetation protection from large wakes that destroy nesting platforms; and 5) sustained water levels greater than 12 inches deep during the nesting season.
Lewis" Woodpecker
This woodpecker inhabits open forest stands and feeds primarily on insects from spring to fall and on mast (acorns) and com, preferrably left standing or spring-plowed, during winter. Destruction of winter habitat represents a greater threat to the species than loss of breeding habitat because of the more specialized winter feeding requirements (Sousa 1983). Because the birds are opportunistic feeders, no minimum critical habitat areas can be designated.
Prime feeding and breeding habitat requirements are as follows (Souse 1983):
1) Large cancpy trees should be present, with between 30 and 75 percent canopy closure; 2) at least one dead snag per acre should be present for cavity nesting and mast storage; and 3) distance between winter food source (oak trees and standing corn crops) should not exceed 0.5 mile.
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Common Yellowthroat
The yellowthroat is a small warbler associated with wetland areas. They feed for insects at the water or mud surface and construct nests on the ground or on aquatic vegetation slightly above water level. Dense shrub or herbaceous wetland vegetation is required for concealment.
Prime habitat requirements have not been researched as thoroughly as the previous species. Minimum habitat area is 1.2 acres, that includes wetland areas of dense emergent vegetation, such as cattails, and stable water levels. An insect source also is necessary (USDA 1981).
Yellow Warbler
These warblers require riparian areas for foraging and nesting, preferring areas of low deciduous growth, such as willows and alders. Nests are generally placed in shrubs 3 to 8 feet above the ground. Males sing from exposed perches. Yellow warblers are reported to prefer edge habitats and territory size is around 0.4 acre.
Prime breeding and feeding habitat requirements include the following (Schroeder 1982): 1) At least 0.4 acres of suitable habitat must be present; 2) deciduous shrub wetland vegetation must be the dcminant stand-type since yellow warblers only occasionally use cottonwood forest stand-types; 3) optimal shrub densities are between 60 and 80 percent crown cover; 4) shrub heights should be 6.6 feet or greater.
General Bird Habitat Requirements
The basic habitat needs are food, shelter, and water. Many books have been written on attracting birds to backyards, and the golden rule seans to be: provide as much habitat variety as possible. Gustav Swanson, noted bird
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habitat observer, recorrmends that water is a critical element and should be emphasized and provided in varying depths so that it is "knee-deep" for all birds (Swanson pers. ccmm. 1987). Water quality is also of concern since many invertebrates that are important bird food sources may not tolerate the levels of pollutants present in rivers and aquifers in the study area. By varying horizontal proximity of landscape elements and by adding a variety of vegetation layers, many non-targeted birds will be attracted to this site along a major migratory corridor. By creating patterns and shapes that are perceived by birds flying overhead as providing the possibility of food, shelter, and suitable nesting sites and materials, then increased bird species diversity should result.
In wetland ecosystems, bird species richness is related to area of open water and the interspersion of open water and dense cover (Weller 1981). Wellers' examples suggest that the highest numbers of species occur in areas with 50 to 75 percent open water and 25 to 50 percent dense wstland vegetation occuring in small pools. Complexes of wetlands increase species richness over solitary wetlands of similar sizes (Brcwn and Dinsmore 1986). Gravel lake design should incorporate this interspersion of deep and shallow areas into reclamation plans.
The South Platte River is aligned with the annual north-south bird migrations and provides refuge and food to break the journey over unfavorable terrain and allows forest bird species to cross through grasslands (Sprunt 1975). Therefore, forest corridors should be provided to provide habiat for migrating forest species.
HUMAN REQUIREMENTS
Visitors to a bird habitat area along the future gravel-pitted South Platte corridor will also have horizontal and vertical spatial needs that should be
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acconmodated. According to Simonds' (1983) previously mentioned ideas, birdwatchers and schoolchildren would generally appreciate a diversity of places and views in close proximity to maintain interest. Horizontally, this may mean walking along connecting corridors through a variety of patches. Vertically, it may mean being at eye level with shrubs for shelter at one point, and high above ireadows or fields for perching at another point. Feeding would take place at sheltered areas with views. Suburban users may require the enclosed, volumetric space that "supplies the elemental animal need for territory" that Condon (1988, p. 33) describes, combined with less spatial enclosure in cannon open spaces.
In addition to physical requirements, humans also require cultural benefits from expending time and energy in a place. A sense of meaning and connection with the rest of the world or perhaps an increased sense of awareness or even a sense of carpetitiveness in the world of "bird-getters" or life-listers. These are requirements that the designer must consider in arranging physical elements on the site and in interpreting than.
The site is within the Denver metropolitan area and is close to lodging, food service, and camping facilities; therefore, overnight facilities and food service will not be provided. Since the land considered (except for the Veteran's Park/Smith Natural Area) is potentially valuable for gravel resources, unmined land would not be considered for permanent structures such as rest roans.
The design should incorporate the following elements:
* Entrances
* Trails
* Interpretation/Qrientation
* Observation Blinds
* Shelter/Nature/Community Center
* Restrooms
* Parking
* Gravel Mining
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MASTER PLAN
Landscape ecological concepts have been woven together with the bird habitat and human use requirements to form a master plan. Physical elements, such as gravel lakes and trails, were designed by drawing fran the concepts of providing spatial and temporal heterogeneity and connections to meet bird and human requirements. The design is presented (figure 22) along with sections (figures 23 and 24) and schematic diagrams (figures 25, 26, and 27) to summarize and visualize how these concepts were used. Habitat improvements are shown in figure 28, and are compared to existing and probable development scenarios in figure 29. El orient locations are conceptual and need to be verified by soil and groundwater testing to determine precise locations of designed features.
GENERAL MASTER PLAN ATTRIBUTES
This plan features a complex of large and small lakes, numerable wetland areas clustered along sculpted lake edges and in shallow scrapes, and corridors of layered, open forests and shrubs. Corridors are preserved and reinforced along the South Platte River, and are created to connect important patches within the site and outside the site, such as cemeteries, farm shelterbelts, suburbs, creek drainages, and Barr Lake. They are prominent features of the design that extend the influence of the naturalistic area. Contiguity with the South Platte River trail system as well as with Barr Lake State Park is a connection of benefit to Denver area recreationists. Spatial variety is provided on a horizontal and vertical basis, by creating bird-attracting and human-pleasing patterns with vegetation and by layering vegetation to increase habitat niches and visual interest. Finally, because gravel pit development will take place over a
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50+-year time frame, depending on danand for this resource, vegetation will achieve temporal diversity by virture of being planted at varying intervals over time. In addition, existing mature canopy trees will be replanted with other canopy trees in similar patterns so that existing corridor configurations are maintained. This staggered planting scheme coupled with the river shifting in sane locations (permitting riparian vegetation to reestablish), will allow this design to maintain its integrity over time.
NATURALISTIC FEATURES Gravel Lakes
This plan shows considerable variation in the sizes and shapes of the gravel lakes. The smallest lakes occur to the north and are separated by dikes that would vary in width and in configuration to offer a variety of views and contact with the lakes, adjacent vegetation, and birds. Although the Tuttle Applegate Rindahl, Inc. plan for Bromley Lakes has been approved and excavation begins in 1988, it is proposed that plans be amended to reduce the size of the proposed lakes, create islands, and vary the lake edges to a more significant degree.
The numerous, amoebic wetland edges create coves for wildlife feeding, nesting, and resting, which, of the targeted species, is especially valuable for western grebes. Habitat for endangered small fish species such as the northern red bellied-dace can also be provided along these sculpted edges (Woodling, pers. ccmm. 1988). Islands are designed to provide additional cover/water and marsh upland edges, which can increase population density of seme bird species (Weller 1981). Extensive shallow areas are designed with side slopes varying from 10:1 to 4:1 to support a variety of water depths
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and wetland plants, which would be beneficial to all targeted species except Lewis' woodpecker. This begins to approximate Weller's recommended interspersion rate of 50 to 75 percent open water with 25 to 50 percent dense, clustered wetland areas (Weller 1981).
Shallow scrapes appear in two designated areas, entailing removing vegetation and soils until contact is made with the water table, a depth of 2 to 5 feet. The scrapes are maintained at 6-inch to 2-foot depths and planted with a variety of vatland plants. Again, all species (except Lewis' Woodpecker) would benefit frcm the creation of shallow wetland areas.
The east end of the lake adjacent to the proposed housing subdivision is developed as a beach with shallow slopes. Sailboard rental and other ncn-motorized recreational activities take place from this point. Lakes serve as visual breathing rocm in the plan to combat too much diversity in too small of an area, which could otherwise result in confusion or tension (Simonds 1983).
South Platte River
In several locations, it is proposed that the river not be channelized according to the UDFCD plan; it would not be necessary because gravel lakes would be further away frcm the river than the minimum 400-foot distance (Wright Water Engineers 1985), and it would allow sane semblance of natural processes to take place. In these areas natural channel erosion and deposition would be allowed to continue until the river shifts to within 100 feet of a gravel lake. At that point, riverbank stabilization would take place. The benefit is that a wide river corridor would allow deposition of alluvium and the subsequent establishment of riparian vegetation, which
90


otherwise would have to be planted to replace the functions of existing decadent cottonwood stands that are so important for herons, woodpeckers, and kingfishers.
Large boulders are placed in the river channel in three locations to create alluvial deposits and riffles where kingfishers and great blue herons fish. These boulders are strategically placed under perches that hang over the river.
Ditches and Third Creek
The Brighton Ditch remains unchanged except for relocation of the diversion dam if the South Platte is relocated from the existing location (UDPCD 1984). The McCann Ditch is changed considerably as it flows through the study area. It is routed east of the gravel lakes and flows between the subdivision and the lakes. The width of the ditch varies; in sane locations, it will be widened to create wetland stepping stones or larger wetland areas (described in more detail in the Smith Natural Area section to follow). Water shares may have to be purchased to use water on-site (Tuttle pers. ccmm. 1988). Third Creek, which connects to Barr Lake, is also widened to create connecting corridors for wetland bird species (figure 24).
Vegetation
Over the next 50 years, the study area could become a series of lakes interconnected with different types of wetlands and upland vegetation.
While native species should be used along the river corridor to prevent perpetuating the spread of non-native phreatophytes (water-loving plants), non-native plants should be used in other locations to attract birds. Proposed wetlands, open forest, shrub, and agricultural plantings are designated on the master plan.
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Wetland plants are established along the sculpted lake edges, along ditch and Third Creek drainages, and in scrape areas. Riparian wetlands also may become established in places where the river is not channelized, which may eventually replenish prime great blue heron, kingfisher, and Lewis' woodpecked habitat. Eastern lake shores will require iirmediate stabilization efforts so that plants are established before winds create banks too steep and erosive to support vegetation (Gooper pers. canm. 1988). Different wetland communities, ranging from shrub-dominated to floating plant-dcminated communities are incorporated into the design.
Existing cottonwood forest stand-types are supplemented by plantings of deciduous canopy trees, such as cottonwoods, hackberries (these trees attract insects, which may benefit Lewis' woodpeckers, yellowthroats, and yellow warblers), and oaks (for the mast-feeding Lewis' woodpeckers). Most of the targeted species prefer openings in the canopy, so supploriental plantings should not create areas where closure is greater than 70 percent (Sousa 1982). Corridors of these trees also extend into the suburbs and into farm shelterbelts. Shelterbelts are designed for maximum bird species diversity. They are comprised of multircws of deciduous and evergreen trees and shrubs, with open grassy areas between tree and shrub layers (Schroeder 1986). These shelterbelts function to: 1) provide habitat for bird species; 2) create cooler, moister microclimates as they slow wind and cause snow deposition; and 3) create species movement corridors (Forman and Baudry 1984). They also function in agricultural and suburban areas to create volumetric spaces and serve as the "walls" of the "rooms" created (Condon 1988).
Presently, the shrub layer is depauperate in the study area due to grazing and should be replanted to attract songbirds and other bird species. Along wetland margins and water courses, patches of tall shrubs, such as sandbar


Full Text

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BIRD HABITAT DESIGN FOR PEOPLE: . A LANDSCAPE ECOLOGICAL APPROACH

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BIRD HABITAT DFSIGN FOR PEOPLE: A LANDSCAPE EXXlr..a.3ICAL APPROACH Abstract Joan Hirschman 3803 Silver Plume Circle Boulder, CO 80303 (303) 499-6441 Bird watching is evolving into a SfX)rt with mass appeal, according to Tirre magazine and the U . S . Fish and Wildlife Service. In Colorado, hCMever , the best places to watch birds are under the highest development pressure: w::!tlands and riparian corridors. This thesis advocates developing a bird habitat area in the Denver metropolitan area along the South Platte River because prime habitat for declining bird species is needed as develcpment pressures increase and because watching birds is a source of delight for people. Appropriate tools f o r designing bird habitat in a human-daninated setting are provided fran the science of landscape ecology. A landscape ecological approach encourages designers to evaluate a site in a threedimensional, dynamic context by looking at its structure, function, and heM it changes. Forms can be generated by applying concepts of s:patial and temporal heterogeneity and the concept that connected areas provide better habitat and recreation fX)tential than isolated areas. From these concepts, several scales of designs are generated for a 2-mile section of the South Platte River in the vicinity of Brighton, Colorado, an area that will lik e l y be gravel mined for upcoming airport and highway constructio n projects. To extend the influence o f the designed habitat and recreational corridor, designs are generated for adjacent farms arrl suburbs to derronstrate how providing bird habitat can have practical as w::!ll as enjoyable benefits for adjacent landowners. A core park is also designed that includes agricultural, suburban, and w::!tland derronstration gardens. These gardens incorporate landscape ecological concepts of heterogeneity and connections and are interpreted for visitors so that visitors can use these ideas for their own land. Finally, the impact of this bird habitat area is explored again on the regional scale and scenarios are presented that shCM how concepts used in the design should be applied on a regional basis.

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UNIVERSITY OF ffiWRAOO AT DEVER A THFSIS SUif.1ITI'ED 'IO THE FACULTY OF THE PRcx:;RAM IN I.ANDSCAPE ARQfiTEX:'ruRE AND URBAN DESIGN IN PARTIAL FULFILI.MENI' OF A MASTER OF LANDSCAPE ARQfiTEX:'ruRE DffiREE SCHOOL OF AROfiTErl'URE AND PI..ANNJN3 ACCEPI'ED : BY JOAN HIRSCHMAN DENVER, COWRAOO MAY 1988 Frederick . Steiner, School of Architecture and Planning, University of Colorado at Denver Wiens , Ecolog1 Dei:xrr:/.InE=nt of Biology ado State University

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I wish to thank my thesis committee members , Frederick Steiner, Bill Vitek, and John Wiens for providing wisdom and professional guidance as I passed through each phase of this thesis. The fact that the groups' s diverse interests were congenially and constructively brought together in our meetings reflect the fine abilities of the corrmittee members as well as the inherent interdisciplinary nature of the topic selected. If Carl Troll is correct that landscape ecology is a state of mind and that those who approach our environrrent as a coherent system are landscape ecologists, I v.as fortunate to work with three landscape ecologists. I am also grateful to coworkers , friends, and fellow students, especially Patty Sacks , Crystal Gray, and Al Terry for taking the time to listen and help sort out what often seemed like an overwhelming endeavor. My deepest appreciation goes to David Cooper . His dedication to understanding large-scale patterns of nature and applying this knowledge to many situations has been a major inspiration in creating this thesis. Plus, it is always great to watch birds with him.

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CONI'ENI'S ...................... . ................................... ii QJAPl'ER ONE: INI'RODUCI'ION, ME:I'HOOOUXN, AND ..................... l Introouction ..... ..................................................... 1 .Methooology ........................................................... 4 Landscape Ecology and its Relationship to this Thesis ............ 4 Design .Methodology ...................................•........... 7 Naturalistic Bird Habitat Area Objectives ............................. 8 Process SUITITB.ry ....................................................... 9 ClJAPrER 'IWJ: SITE AT THE RffiiONAL SCALE -THE BIRD' S EYE VIEW .. ll Introouction ......................................................... 11 Land Classification .................................................. 11 Region ............ .. ............................................ 11 Landscapes ...................................................... 12 Applicable Concepts from Landscape Ecology ........................... l9 Spatial Heterogeneity ........................................... 19 Tenporal Heterogeneity .......................................... 28 Connections ..................................................... 32 Site Criteria ........................................................ 3 4 Site Selection .Methods ............................................... 34 Identifying Important Habitat Areas within the Region ........... 35 Site Selection .................................................. 38 s UI1'1l'\ary • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 3 9 CHAPI'ER THREE: UNDERSTAND THE SITE AND USERS AT THE LANDSCAPE SCALE ... 41 Introouction ......................................................... 41 Site Analysis ........................................................ 41 Location ........................................................ 41 Clilnate ......................................................... 43 Geology ......................................................... 43 Hydrology ....................................................... 44 Soils/Grave 1 Resources ......................................... . 52 Topography ............................ . ......................... 53 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Wildlife ........................................................ 58 People .......................................................... 60 Integration of Site Analysis Information ........................ _. . .... 65 Site Structure, Function, and Change ............................ 65 Comparative Landscape Structural Analyses ............................ 73 SUITU1B. ry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3

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CHAPTER FOUR: LANDSCAPE SCALE SITE DESIGN ................................ 76 Intrcduction ......................................................... 7 6 Design Objectives .................................................... 76 Key Users ............................................................ 7 7 Birds ..........................................•................ 77 People .......................................................... 78 Design Program ........•............................. ................. 79 Bird Habitat Requirements ....................................... 79 Huma.n Requirements .............................................. 84 Master Plan .......................................................... 86 General Master Plan Attributes .................................. 86 Naturalistic Features ........................................... 88 CUltural Features ............................................... 96 Summary ............................................................. 1 01 CHAPTER FIVE: LOCAL SCALE SITE DESIGN ................................... l09 Introduction ..... ................................................... 10 9 West Bromley Lakes .................................................. 1 09 Subdivision Scale .............................................. 110 Neighborhood Scale ............................................. 115 Residential Plantin g Design Scale .............................. ll5 Adjacent Agricultural Land Design ................................... ll8 Veteran's Park/Smith Natural Area Design ............................ l20 Park Scale ..................... ................................ 120 Core Park Scale ................................................ 122 Surrrnary • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 2 5 CHAPTER SIX: DESIGN IMPLICATIONS AT THE REGIONAL SCALE •••••••••••••••••• l26 Intrcduction ........................................................ 126 Regional Accomplishments of this Design ............................. l26 Potential Regional Accomplishments of this Design ................... l28 Surrrnary • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 3 0 CHAPTER SEVEN: CONCLUSION ............................................... 132 Introduction ........................................................ 132 Efficacy of Landscape Ecological Methodology ........................ l32 Other Design Approaches and Future Research Needs ................... l34 Overall Relationship Between Landscape Ecology and Design . .......... 136 SEI...EX:TED REFERENCES • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 3 8 PERSONAL ccr.1MUNICATION ................................................... 14 4 APPENDIX ................................................................. 14 5 Targeted Species' Associated Guilds FIGURES: 1. Region ................................................................. 2 2 . Process Chart .......................................................... 9

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3 . Landscapes ............................................................ 14 4. Nature Preserves ...................................................... 21 5. Heterogenous Habitat Needs-Herons ................................... 22 6. Patch Shapes -Birds .................................................. 24 7. Patch Shapes-People .................................................. 27 8. Heterogenous and Homogenous Plantings ............................. .... 29 9 . Heterogenous and Homogenous Plantings Over Time ....................... 3l 10. Connections ........................................................... 33 ll. Potential Design Sites ................................................ 37 12. Site .................................................................. 42 13. Groundwater Contours and Wells ........................................ 46 14 . South Platte River Watershed and Tributarie s .......................... 47 15. Floodplain Boundary ................................................... 48 16. Geologic Cross-sections and Mineral Deposits .......................... 54 17. Probable Development and Prime Habitat ................................ 6 3 18. Patche s ............................................................... 68 19. Corridors ............................................................. 6 9 20. .M:l.trix ................................................................ 71 21. Existing Prime Habitat ................................................ 80 22 . .M:l.ster Plan ........................................................... 8 7 23. S ections .............................................................. 89 24. Sections -Barr Lake Connections ...................................... 92 2 5 . Sp:l. tia l Heterogeneity : Shapes ........................................ l 0 3 26. Temporal Heterogeneity ............................................... l 04 27. Connections .......................................................... lOS 28. Proposed Development and Prime Habitat ............................... l06 29. Prime Habitat and Comparative Development Scenarios .................. l07 30 . Subdivision A ........................................................ lll 31. SUbdi vision B ........................................................ 1 13 32 . SUbdivision C ........................................................ 114 33. Neighborhood ......................................................... 116 34. R esidential Planting Plan ............................................ 117 35 . Adjacent Farm ........................................................ 119 36. Bird Habitat Park .................................................... 121 37. Core Park ............................................................ 124 38. Landscapes -Scenario A .............................................. 129 39 . Landscapes -Scenario B .............................................. 131 TABLES: l. Precipitation ......................................................... 4 3 2. South Platte River Flood H ydrology .................................... 49 3 . Common Wildlife Species in the Study Area ............................. 59 4. Comparative Descriptive Landscape Structure Models .................... 74 5 . Targeted Species ...................................................... 77

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CHAPI'ER ONE: INI'RODt.JCriON, MEI'HOOOLCGY, AND OBJ:Erl'IVFS INI'RODUCI'ION Birdwatching is an increasingly popular form of recreation in Colorado and throughout the United States. According to the Colorado Division of Wildlife (DOW), numbers of birdwatchers are substantially increasing in the Denver rretropolitan area ( Hernbrod pers. ccmn. 1988). At the same tirre, the number of bird species in this area is fluctuating; sane bird pcpulations, particularly those dependent on v.etland and riparian habitat, are declining and because of this, are considered to be 11 Species of Special Concern 11 by the row and by local experts (OOW 1985, Figgs pers. cmm . 1987 , Chase pers. canm. 1987) . Because of increased developrrent pressures in wetland and riparian areas, it is becoming increasingly important to provide habitat for declining species as well as species of enjoyment to birdwatchers. This is especially true along e1e South Platte River, the most important riparian habitat and bird migratory route in the Denver area and northeast Colorado . The South Platte River has become a largely industrialized corridor with few remaining natural patches along the 404nile section from Brighton to Chatfield Dam, south of Denver (figure 1) . High-quality gravel deposits within the South Platte floodplain and high local demand for the gravel have resulted in the conversion of much of e1e riparian/agricultural corridor to a channelized riparian/gravel pit lake corridor. The remaining unmined portions of the South Platte corridor are under additional pressure with the recent advent of a new airport and new highways within the Denver metropolitan region. 1

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After mining, this land is of minirral ec:nnc:rnic value. cannot sell it for housing, farm it, or industrialize it further. In fact, the remaining steep-sloped lakes are often a liability to landowners after mining as lakes must be fenced and protected from trespassers. This lakedotted riparian corridor (its scale best appreciated by aerial photographs), if properly designed, could become part of an outstanding system of bird habitats within the Denver metropolitan region, which have great educational :pJtential and are within easy reach of over me million people. The term "natural area" when applied to a city or rural area is usually an ano rnal y . By definition, "natural" means "not art if icia l or man-made" (Morris 1976 , p . 875). Often the so-called natural area is a completely isolated remnant patch of older vegetation that no longer has natural functions, such as harboring high species diversity and slowing nutrient runoff (Forman and Gcxlron 1986) . Or the area is highly m:::dified but unbuildable, such as a gravel pit, that can be recreated into a "natural" (meaning green but perhaps green with native grasses and shrubs instead of bluegrass) area. City natural areas are usually physically separated from the surrounding url:an area by fences and by their messages. If used for education, interpretive themes are often slap-on-the-wrist messages that revolve around the dreadful ilnpact hullaDs have had on the environment. Lagging monetary supr:ort for many nature centers may indicate that this approach is not working effectively. To reduce the contrast, more creative integration needs to occur between natural areas and surrounding CClll!Tlunities . Instead of reducing contrast by creating more suburbs and fewer natural areas, the trend should be reversed and the influence of these natural areas extended more into and through adjacent urban, suburban, and/or agricultural lands. Perhaps a 3

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cross between "naturalistic" areas (a more accurate term, implying areas created that resemble nature) and the surrounding crnmunity soould be encouraged so that horres serve to extend the functions, such as bird habitat, of the naturalistic area. This could result in the formation of a greater constituency for bird habitat protection, since bird-watching areas would be more accessible, and could also result in the formation of more connected habitat areas that better fulfill the functions of larger preserved areas. This thesis has two purposes. The first is to advocate improving habitat for declining resident and migratory birds in the Denver metropolitan area, since human development is causing the decline of species dependent on riparian and wetland areas, and because watching birds and being involved in their varied landscapes is a source of delight for many people. The second purpose is to evaluate the effectiveness of applying landscape ecology to site analysis and design of a hybrid between local communities and natural bird habitat areas, referred to in this thesis as a "naturalistic bird habitat area." METHQ[X)r.cx:;y Landscape ecology is presumed to be an appropriate tool far designing a naturalistic bird habitat area because it emphasiz e s connectivity l:etween sites with different land uses. In this section, landscape ecology is described in relationship to ecology and design. Based on this brief summary , a design methodology is presented. LANDSCAPE ECOLOGY AND ITS RELATIONSHIP TO THIS THESIS Landscape ecology is a recently-emerging field ln Europe and the United States that emphasizes study of the landscape, a focus that implies a 4

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certain large scale as well as a holistic approach (Galley 1987). B y definition, "landscape ecology explores how a heterogenous combination of ecosystems ( wcxx1s, meadows, villages, etc. ) is structured, functions, arrl changes" (Fonran and Godron 1986) . The present (although not historical) tendency in eoology is to study irrli vidual species or camnunities in pristine environments where human-induced variables are reduced to the greatest extent possible (Goldsmith 1985). As ecologist Richard Forman statErl, "Ninety percent of ecological studies 'M2re taking place in two percent of the landscape" (Fonnan pers. camn. 1987). Landscape eoologists study landscape-level spatial patterns (best appreciated on aerial photographs), the interconnections between these patterns, and the effects of or from these interconnections over tiTre , within a continuum of land use types ranging fran pristine to urban lands. Because of the focus on a landscape's spatial qualities and the realistic tendency to study interactions within arrl between human-affected landscapes, landscape ecology is growing with the collaboration of many disciplines, especially landscape architecture. What, then, is the difference between eoology and landscape ecology as applied to design? McHarg's classic design system (1969) has been labelled ecological design because it is based on " a presumption for nature" (tvk:Harg 1969, p . 12) . Consistent and thorough resource consideration is the key to making sound design decisions, according to Design With Nature and this approach has been widely incorporate d into planning and design processes around the world. As the method of canpiling and overlaying resource data layers was incorporated into design processes, it has become distilled into a method that primarily considers existing resource conditions, arrl not the spatial and /or temporal qualities of the site resource s . This distilled version is the approach most often referred to as eoological design. 5

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Ecological design critics recognize that the approach is sensitive to ecological processes, but does not fully incor_!X)rate resident and user input in the design process and results in "the sacrifice of cherished and legitimate values, the simple pleasure taken in creating or experiencing canpositions that please the eye" and perpetuating monoton y (Howett 1987 , p. 7) . Landscape ecological design, by addressing the spatial and tem_!X)ral qualities of settings that are inevitably shaped by social, cultural, and economic factors, is distinctly different from this distilled ecological design approach, and may be more appealing to critics of ecological design. By same definitions, ecological design and landscape ecological design are synonymous. According to Koh (1982) , ecological design: " ... is more inclusive than energy-conscious design. Its conception of the environment is at once physical, biological, cultural, and psychological. The energy-efficiency of an environmental structure and the protection of the human environment are here considered as interrelated and mutually complementary outcomes of the ecological and evolutionary fit J:etween the bui 1 t structure and its natura 1 and cu 1 tural environrrent" (p .79). In this thesis, a landscape ecological approach is taken to select, analyze, design, and interpret a site for use by people and birds because the approach provides concepts that are to a landscape architect at a variety of design scales. These concepts, explained in more detail in following chapters, focus on understanding the structure, function, and dynamic qualities of an area, from a regional scale down to a backyard scale. Other useful concepts that can be applied from landscape ecology include designing for long term spatial and tem_!X)ral heterogeneity and designing linkages to irnr:ortant habitat areas. The hypothesized benefits from using a landscape ecological approach in this thesis are: 1) the approach will serve as a useful evaluative tool that enables the designe r to 6

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classify and inventory the landscape in a synthetic way that considers structure, function, and change over time (Forman and Godron 1986 , Hall 1988); 2) the approach will be an appropriate design development tool that provides a basis for generating forms based on concepts of spatial and heterogeneity and interconnections; and 3) this relatively new field will be applied to design in a unique way not tested before, with results contributing to both fields of landscape architecture and landscape ecolCXJY. DESIGN METHOCOI.J:X;Y Naturalistic bird habitat area design involves six stages. First, a regional approach is taken that analyzes the Denver metropolitan area, especially the South Platte River corridor between Brighton to the north and Chatfield Dam to the south, a distance of 40 miles. L:':l.ndscape ecological concepts, prirrarily from Forman and Godron's text (L:':I.ndscape Ecology 1986), are used as a framework. Thes e concepts of spatial and terrpxal heterogeneity and interconnections between similar areas are used in all stages of this thesis and will be described later. Site selection criteria are then established for a bird habitat area. Finally, using aerial photographs and visiting different sites, an area is selected that meets these criteria. In the second stage, the selected site is analyzed first through a resource layer approach. This inforrration is then integrated in terms of how the site: l) is structured, using aerial photographs to recognize repeated structural patterns such as corridors, patches, and the rna.trix (terminology is defined in chapter three); 2) functions, including movement of species, nutrients, and energy from one landscape to another; and 3) changes, noting the dynamic qualities of the site in its hurna.n-dominated setting. 7

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Third, site design objectives are formulated, key users identified, and a design program developed that incorporates bird habitat and human requirements. The site is then designed at a master plan scale, emphasizing use by people and targeted birds, connections to other areas to extend the influence of the design, and long-term sustainability of the design. Local-scale design is the fourth stage that demonstrates that concepts can be telescoped down from the regional scale to a residential planting design scale. Adjacent suburbs, farms, and a park are designed to show specific connections beyond the bird habitat area. The influence of the design is then applied back to the regional scale in the fifth stage to demonstrate the achieved impacts of the design on a larger scale, and to explore :potential future repercussions of the d esign. Finally, the overall effectiveness of using principles of landscape ecology in bird habitat design is evaluated. Figure 2 sumnarizes the methodology used in this thesis. NATURALISTIC BIRD HABITAT AREA OBJECI'IVES Objectives for this naturalistic bird habitat are a are: l) To play a role in providing bird habitat for declining resident and migratory birds (as define d by row and local experts) on a regional and local scale; 2) To be responsive to changing land-use patterns along the South Platte Ri ver; 8

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lb I { l .f ... .... t . ""'ian Lief; oeiine, . ...... . JM .I -..; 3'-' 10 ...,J .,.._ ! l

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3) To extend the influence of habitat provision to communities bey ond site boundaries ; and 4) To balance people's non-consumptive , passive recreation needs with the sometimes-conflicting habitat needs of a variety of birds. 10

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CHAPI'ER 'IW): SITE SELECTION AT THE RffiiONAL SCALE -THE BIRD 's EYE VIEW -----------INI'RODUcriON The classification concepts of region, landscape, and landscape elements set the stage for discussing three concepts that provide design guidance throughout this thesis: the positive effects of spatial heterogeneity, temporal heterogeneity, and interconnections. The concepts are then used in defining criteria for selecting a site for the naturalistic bird habitat area and then the site itself. LAND CLASSIFICATION The five-county Denver metropolitan area was selected for this thesis because of its growing population of birdwatchers, its increasing urbanization, and the value of wetlands and riparian areas in this semi-arid region. The Denver metropolitan area was further narrowed do,.m to the South Platte River corridor between Chatfield Reservoir to the south and Brighton to the north because of the importance of the South Platte River for migration and bird habitat. These two endpoints to the study area signal the limits of suburban Denver extents at present. Following the river in either direction away from the urban area will bring a traveller to rural surroundings, although the rural flavor of these areas may soon change . RffiiON A region is defined by Steiner et al. ( 1981) , as " an uninterrupted area possessing same kind of homogeneity at its core, but lacking clearly defined limits." Lyle ( 1985) acknowledges the planning region, defined by the ll

PAGE 19

geographic extent of issues considered. Th e region considered in this thesis incorporates both definitions and was selected by the extent of relatively homogenous urbanization in a north-south direction (from Chatfield Reservoir to the south and Brighton to the north), by the mountain front to the west, and east Aurora to the east (figure l) . This is also the area studied by regional transportation planners for the ring-type transportation system now under construction for the Denver metropolitan area (DRCOG 1987) as well as the region studied by Denver City Planner De Boer ( 1965) . According to Forrn.:m and Godron ( 1986) , a region almost always contains a number of landscapes; the region considered in this thesis has this characteristic as well (figure 3) . Information at a regional scale is plentiful and has been provided in mor e detail in the Regional Transportation Ecological Planning Study (Development Research Associates, Inc. and Wallace, McHarg, Roberts and Todd Inc. 197 2) , and in "Major Drainageway Planning Documents : Phases A and B " by the Urban Drainage Flood Control District (UDFCD 1984) . Natural and cultural resource information from these documents will be woven into site analysis information presented in Chapter Three. lANDSCAPES A landscape is a "heterogenous land area composed of a cluster of interacting ecosystems which is repeated in similar form througoout its kilaneters-wide extent" (Forman arrl Godron 1986 , p . 31) . Landscapes may vary in size from hundreds of miles, such as an agricultural area in eastern Colorado, down to a few miles in diameter, such as a srrell city surrounded by agriculture, like Brighton, Colorado. 12

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Landscapes can be identified on aerial photos, usually by vegetation structure, where there are distinct and rreasurable changes. J. B. Jackson, an historian whose exploration of landscapes errphasizes how our surroundings reflect our culture, also recognizes the aerial aspects of landscape analysis. He requested articles for his journal Landscape to be accanpanied by aerial photos because, according to Jackson: "It is from the air that the true relationship between the natural and the human landscape is first clearly revealed" (M::!inig 1979, p. 197). Landscapes are formed by three mechanisms or::erating within a landscape boundary : geanorphological processes taking place over a long time (weathering of bedrock, changing river patterns, etc.), colonization patterns of species (including people), and local disturbances to individual ecosystems over a shorter period of time, such as flood impacts from the South Platte River. In sum, a landscape is a distinct, rreasurable unit defined by recognizable and spatially-repetitive clusters of interacting ecosysterrs, with similar georrorphological processes and disturbance regimes. A region has a less visible boundary than a landscape does. Landscape ecology also recognizes the critical role humans play in detennining how landscapes are structured, function, and change. All characteristics of a modern landscape, by landscape ecological definitions, are determined by social, fX)litical and econanic factors. J .B. Jackson further emphasizes that: "Landscape is not scenery, it is not a political unit; it is really no more than a collection, a system of man-made spaces on the surface of the earth. Whatever its shape or size it is never simply a natural space, a feature of the natural environment; it is always artificial, always synthetic, always subject to sudden or unpredictable change. We create them and need them because every landscape is wher e we establish our own hunan organization of space and time ... A landscape is where we speed up or retard or divert the cosmic program and imfX)se our own" (1984, p. 156). 13

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Several types of landsca:pes occur in the region selected for this thesis (figure 3) . These include urban/suburban, industrial, and agricultural. Geomorphological processes (e.g. erosion and deposition) are similar among these three landsca:pes, but colonization patterns and disturbance regimes are different. Ea.ch landsca:pe is described in terms of its colonization patterns and disturbance regirre, which affect the structure, the functions that take place, such as water, nutrient, and species flow, and changes over time. Urban /Suburban Landscape The urban/suburban landscape along the South Platte has been colonized over a 100-year period by humans in a regular rranner. Land use is daninated by housing and office units and few natural remnants renain within this region. Once a natural landscape i s urbanized, the process is generally onedirectional; the landsca:pe remains urban and generally does not return to a natural condition o ver time. Transportation and inforrration systEms are numerous , and species diversity is extrerrely law, except in park-like settings such as back yards, cerreteries, and golf courses, wher e planted species are varied and generally non-native. Resident bird communitie s are depauperate in the urban/suburban landscape in comparison to a natural landsca:pe, but density is high due to the daninance of house sparrows am starlings (DeGraff 1975) . Domestic :pets, collisions with buildings with reflective glass, and highway mortality are common threats to birds in urban environrrents ( Panks 197 9) . Drainage fran urban/suburban landscapes is usually subsurface in stonn until channelized streams are reached. W3tlands can occur in poorly drained areas, along drainage swales, am in undeveloped pro:perties where drainage is not d esigned. 14

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• / . . . . I J . / :" AREA { . . / . '\. l . -)

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Industrial Landscape Urban/suburban and industrial landscapes along the South Platte River are grouped separately because of differences in colonizational and disturbance regimes . The industrial corridor in the selected region is comprised primarily of gravel mining operations, sewage treatment facilities, a meat packing plant, and other industrial complexes adjacent to the river. The gravel minedominated landscape was colonized once by humans for gravel extraction, and then reclairred to a more "natural" landscape following mining . Disturbance is two-directional as natural rerrmant patches are mined and then reclairred as required by law. large lakes dominate portions of the industrial landscape, with 100-400-foot-wide strips dividing lakes in many places (a 100-foot buffer must be maintained between a gravel pit arrl the river or other lakes if the bank is protected with riprap or similar materials. If there is no bank protection, the corridor must be 400-feet wide) (Wright \'Jater Engineers, Inc. 1985 , Gra y pers. cc:mn. 1988) . Gravel extraction along the South Platte River has resulted in wid espread destruction of riparian and v.etland habitat, but, along with darn construction, also created bodies of water for wintering waterfowl use. Catchpol e (1975) emphasizes that the value of gravel pits as potential conservation areas for breeding bird communities in proximity to rapidlyexpanding url:an environments is high. Many gravel pits along the South Platte were excavated without regard to providing a variety of wetland and terrestrial habitat. As a result, they provide little wildlife habitat, due to 1:1 sideslopes that are highly erosive and cannot support plants, and general oligotrophic conditions. Future reclamation of proposed pits rray be subject to more stringent regulation, ard these pits may serve as better habitat buffers against adverse urbanization factors operating in 16

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surrounding urban-agricultural landscapes (Wright Water Engineers, Inc. 1985) . Few are present in developed industrial areas. The visual character o f the industrial landscape varies according to the particular industry. Typically, gravel mining provides open vistas that are interrupted by vertical stockpiles, fences, and mining equiprrent. The contrast between adjacent urb:m/suburban landscapes is grffit, but the gravel lakes are consistent i n visual quality with the flat, open agricultural fields, and provide an open contras t to the density of urban and suburban developnent. Agricultural Landscape The agricultural landscape (including grazed lands) along the South Platte is characterized by much hunan density than the urban/suburb:m landscape and is rough l y equivalent in human density to the industrial landscape. Agricultural colonization patterns by hurrans are of shorter term than either o f the two previously described landscapes. Land along the Soutl1 Platte has changed from natural, to agricultural, and then to urban/suburban or industrial. Although not as isolated and patchy as the natural remnants along the South Platte corridor, much of the agricultural landscape may became urban or industrial within the next 50 years. The disturbance regime in agricultural landscapes differs from the other two landscapes in that open, relatively hanCXJenous monocultures are created and perpetuated through hunan intervention such as plowing, planting, grazing, irrigating, and spraying. throughout the landscape. These disturbances occur on a regular basis Landscape elerrents include fields, hedgerows, roads, farmyards, and drainage ditches or swales too wet to plow. Erosion control methcds such as growing winter cover crops or minimum tillage are l7

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advocated by county soil conservation districts (Baffe pers. camm. 1988). The visual character of the agricultural landscape within the region is characterized as "functional" as opposed to "picturesque" ( Nassauer 1987). This means tffit the farms tend to be relatively flat, gecrnetrically regular, and rather hanogenous areas, with trees and farm buildings providing the vertical accent, rather than setting the pattern. In picturesque landscapes, however, trees, buildings, rolling hills and diverse vegetation set the pattern. SUburtan development next to functional farms typically occurs as a linear wall of houses parallelling a main road, emphasizing the contrast l::etween the two landscapes. The agricultural bird community consists of a small number of abundant and widespread core species, notably starlings, pigeons, and red-wing blackbirds. Rare species are incidentally found in odd patches of suitable habitat. Mixed farming (tillage and grazing) provides the most diverse habitat which supports a greater variety of birds tffin either type of farming alone (O' Connor 1986) . Where only tillage takes place on a farm, habitat diversity can be achieved by alternating two or more crops within the same field, and by increasing the nurnl::er of intersection points of different crops (Kress 1985). Shelterbelts, particularly when tree s and shrubs are combined in wide swaths, provid e extremely important habitat for b irds in agricultural settings because they provide movement corridors as w ell as feeding and breeding habitat (Yahner 198 3 , Farnan and Baudry 1984 , Forman and Godron 1986 , Schroeder 1986 ) . vetlands are ofte n locate d along irrigation ditches wher e leaks occur and troughs or springs where cattle drink. These are not ploughed and often support breeding bird populations. 18

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APPLICABLE CONCEPI'S FRCM THE FIELD OF LANDSCAPE EXX)u:x:;y The three follONing concepts "'M9re derived from a o f references in the field of landscape ecology. Sorre aspects of these concepts, such as the effects o f patch shape on anirra ls, are still considered "research frontiers" and require verification, especially in the arid west. SPATIAL HETEROGENEITY Spatial heterogeneity can be thought of as a diversity of horizontal and vertical spaces; the emphasis in the field o f landscape ecology on spatial h eterogeneity is part of what distinguishes it fran ecology. "Much of the broad field of ecology ... has focused on the vertical relationships among plants, animals, air, water, and soil within a relatively hoiiDgenous spatial unit. In contrast, what makes landscape ecology unique is its focus on the 'horizontal,' that is, the relationships among spatial units" (Forman and Godron 1986 , p . 7). Spatial heterogeneity is a pONerful design tool for the purposes of this thesis because both birds and people respond to it. Spatial Heterogeneity and Birds The following discussion describes spatial heterogeneity in terms of horizontal diversity , which includes patch shapes, and vertical diversity. It has long been known that Canada geese require distinctly different horizontal habitats for different activities: fields for feeding, open water for protection, and shorelines for nesting (MacArthur 1962). Furthermore , vegetation configurations select e d by an individual species for breeding purposes are more or less unique to that species (Wiens 19

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1969, 1973 ; Roth 1976 and others). The concept is significant because many nature preserves select hCX110
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, .. f .... ... . . . ,. . . . , ';-4 ..• .... . . . . . ... . . . "\J' .•. , \l . , ' .... " • .. .

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will not likely reduce potential threats (Wiens pers. ccmn. 1988) . As mentioned earlier, the study of patch and r=atterns and how they affect functions such as flow is an area of interest to landscape architects because findings have implications for the design of spaces and forms (see figure 6) . Vegetation patterns seem to be the rna jor visual clue to which birds respond initially (Weller 1981). Schoener (1971) found that birds flying over a wooded area are more apt to find a long, narrow clearing that is perpendicular to its direction of movement than a round or parallel clearing. Perhaps a similar case is also true in that a perpendicular forested or shrubby area in a grassland or water environment is more noticeable to birds than a parallel area. Thus , a site that features this or similar features descril::ed below rray be selected by a bird over another site that does not have this or other bird-attracting shapes. Convergenc e points where three or more landscape elerrents intersect rray also concentrate anirral species because of the proximity of diverse resources. Convergence points typically, but not always , occur at the tip of a peninsula (Harris and Kangas 1979) . Peninsulas may be important concentrators of sane animal species movement , known as the funnel effect (Forman arrl Godron 1986). Patches with sculpted edges have far greater animal activity along their perimeter than do patches with " smooth," lineal edges (Forrran pers. comn. 1987) . The DOW implements this idea as well by requesting that gravel mine reclarration be designed such that shoreline contours are irregular with peninsulas and bays so that there are a variety of places in which wildlife can feed, hide, and nest (Tuttle Applegate Rindahl, Inc. 1987). 23

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According to research in progress, Fonnan ( 1988) ccmp3.red the edge of two pinon-junir:;er patches in New Mexico . The lineal e dges showed 3 tirres as many animal tracks along the edge as the sculpted patch edge. The sculpted edges, however , showed 9 tirres as much anirral scat as the srrooth-edged patch, but no scat if lobes were larger than 9 meters in width. Forman noted that a srrooth edge may function more as a moverrent corridor for wildlife and may form more of a barrier than a patch with sculpted edges. Generally, a circular patch, with more interior than an ellipse of equal area, has greater sr:;ecies diversity, but functions less as a corridor for movement, has less habitat diversity, and fewer barriers (Fonnan and Godron 1986). Ring patches, where a b elt of vegetation encircles a hole of different vegetation, may result in similar effects as elliptical-shaped patches. Forman (1988) feels that forms in nature and the processes that create them and result from them can be repeated for desired results in land reclamation and restoration projects. There are many other forms that occur that require further investigation as to their effect on species, nutrient and and energy flow. Until effects are further studied, experimentation with different shapes must take place (Wiens pers. coom. 1987). Vertical heterogeneity should also be provided in a bird habitat area. As more layers of habitat occur as a result of vegetation complexity, more niches can be accorrmcdated , and more wildlife sr:;ecies will occur (M3.cArthur et al. 19 62; Wiens 1974 ; Short 1983) . Research by Karr and Roth (1971) indicates that the greatest increase in avian diversity occurred with the addition of shrub and early tree layers, and that added vegetation beyond . that point produced diminishing returns. Roth also found that closed-canopy forests are less patchy and support lower bird sr:;ecies diversity than 25

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forests with broken canopies (Roth 1976) . These specific data can provide assistance to the designer of bird habitat. Spatial Heterogeneity and People r.any of the landscape ecolCXJical concepts described above also apply to human species and are better documented bec ause people can tell a researcher which landscape features are more appealing, and because the field of researchers is widened beyond scientists to include designers, psycholCXJists, philosophers, historians, and so on. From this cadre of experts, this discussion focuses on spatial heterCXJeneity perspectives from Simonds (1983) , Howett (1987) , Koh (pers. comm. 1987) , Condon (1988), and personal observation. John Simonds , in his paradigmatic book , Landscape Architecture (1983) , links spatial diversity and patch shapes with human responses. He affirms the landscape ecolCXJical principle that as heterCXJeneity i ncreases, species movement increases by noting that spaces with complex enclosures (or patch boundaries) stimulate excitement, diversion, curiosity, surprise, and induced movement . As spatial variety increases, interest increases. Spatial variety, therefore, is appropriate when designing for birdwatchers, but, as Simonds says, confined, simple spaces induce repose and relaxation. Perhaps these spaces are more appropriately designed for resting areas within the bird habitat area or in adjacent suburbs. A number of these carefully observed responses can be used by designers to achieve enjoyable places. For example , in a very unscientific experiment involving ten people, the author of this paper quizzed cohorts as to the effect certain shapes sho.vn below v;ould have on them if they were entering a building (figure 7) . Figure 7a was unanimously chosen as the most welcoming patch 26

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'7A

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shape, and figure 7b was on the whol e the most repelling shape. In a suburl::an setting, people are attracted to gardens with a variety of vertical layers and distinct horizontal patterns, but as Howett (1987) ];X)ints out, the conventional way of handling vegetation in a designed landscape differs from the way plants naturally grow ; designed landscapes often lack the vertical diversity of natural landscapes, and therefore lack a garden effect (1987) (figure 8) . In the U . S., people have grown used to and continually repeat planting patterns such as the relt of junipers around the house with a tree in the middle of the front yard, not because they perceive it as reautiful, but because it is what they are used to (Koh pers. ccrnm. 1987). The designer must ask again, when does too much diversity have a negative effect? Simonds (1983) writes that illogically complex spaces produce tension and confusion in people. Condon (1988) argues convincingly that spaces that are fragmented by objects are less desireable than volumetric roams carved from landscapes. Breathing areas are needed that give the eye a chance to rest refore taking in more variety, and edges almg large spaces are iiD];X)rtant places from which people can observe others. These ideas must also be considered when designing heterogenous spaces for people. TEMPORAL HE'IERCGENEITY Temporal Heterogeneity and Birds Heterogeneity must also be provided ln a temporal sense so that spatial heterogeneity will be perpetuated. It is tempting to look at the few remaining stands of mature cottonwoods along the South Platte River as top priority candidates for preservation because provide habitat for birds of 28

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Fgure 8

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interest such as bald eagles, hawks, herons, and owls. However, if a protected area dres not also support a natural mixture of regenerating trees, trees will either die and perhaps be replaced slowly by other species, or rrore mature trees will have to be planted to maintain the mixture of species desired. in the bird habitat area. Thus, species must be able to regenerate to maintain the preserve in perpetuity (Noss 1987) . Methods of achieving temporal heterogeneity without excessive management are to preserve natural disturbance regines such as fire and flooding. Temporal Heterogeneity and People Landscapes that maintain vegetation diversity over time can be more stable , rror e self-perpetuating, and rrore representative of natural processes than their even-aged, planted counterparts. 'Ibo often the work of landscape architects perpetuates unnatural, static, and idealized planted legacies, such as when urban streets or suburbs are landscaped with even-aged trees. Plagues of honeylocusts are gro,.ving old together along city streets. As with the elms along Speer Boulevard in Denver, when one dies, it may be replaced by a much smaller tree, which ruins the cancpy continuity, requires maintenance to replace the noticeably absent trees, and does nothing to preserve the graceful aesthetic effect over time (figure 9) . Planting a variety of trees of different ages can achieve long-term visual quality, reduce maintenance needs, and encourage people to appreciate natural processes. In an article by Baird Callicott (1983), he laments that the evolutionaryecological aesthetic of nature remains unappreciated by the average person because it cannot be represented or interpreted in art b y landscape painters (Howett 1987). Artist Alan Sonfist strives to achieve appreciation for temporal heterogeneity through his work Time Landscape, where h e planted 3 0

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Fldure9 0\li:e. \TME.

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different ages and types of species that comprised the original forests of M:mhattan Island in the heart of densely developed do.vnto,.m New York City . One observer remarked about Time Landscape , " ... it is not one of those unreal projects that has forgotten death" (Ho.....ett 1987 p. 7). According to Ho.....ett, "the time has cane to see this characteristic as a positive asset of such plantings, because it makes more present to our awareness the dessication, death and decay that are part of a natural cycle" (1987, p. 7). CONNEri'IONS Connections and Birds Is it better to preserve one large area or several smaller areas? "In regional landscape planning, preservation of whole ecosystems with a full complement of indigenous genetic diversity is ideal. This demands a complex of both large and small preserves; the combined strategy will maintain species and ecological processes" (Noss 1983) . Vegetated interconnections among natural rermant patches are as important as the size of the patch. A series of srraller preserved areas may encourage the movement of species in an important movement corridor. Thus, stepping stones of habitat for certain species, if carefully located, may be as beneficial, and certainly more economically feasible, as the preservation of large areas (figure 10) . Connections and People According to Kevin Lynch (1964), imageable cities have a high degree of continuity, distinctive parts, and are clearly interconnected . . Furthermore , paths with clear and well-known origins and destinations have strong 32

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------,.

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identities. People like to be connected to other areas, especially for recreation. Regional bike J;E.ths allow for a more regional exchange of people, greater mobility, and variety. Christopher Alexander (1977) advises that connectivity is highly desireable for safe children's play areas, for interlocking fingers of farmland and urban land, for shopping areas, and for opportunities to learn in the city. "Experience is rarely static: almost alwa ys there is motion involved" and interconnections between areas facilitate motion (Simonds 1983 p. 145). SITE CRITERIA Based on the objectives described in chapter one, and concepts described above, the following criteria were developed to be used in selecting the bird habitat area. The site: 1. Must be located along a stream, reservoir, or area of high groundwater to support wetland plants; 2. r.tlst have the potential to serve as an important link between protected "natural" and recreational areas so that it is accessible to birds and people. 3. f>llst be large enough to provide areas of SJ;E.tial and temporal heterogeneity that can be eXJ;E.nded into adjacent land-use areas to increase its influence. SITE SELECTION METHODS First, an assumption was made that important bird habitat can be created if species' life requirements are provided. This assurrption allONs the 34

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designer to select a site where the best habitat may not already be providErl, but where the potential for providing habitat is high. MacArthur et al. (1962) suggest that a species should be present in a habitat if its patch type(s) (or niche) is present, if other resources in that habitat are adequate , if canpetitive pressure fran other species for all or part of that patch type is lo.v, and if the patch can be reached by individuals of that species. Second, information regarding illlfX>rtant habitat areas within the selected region and general vicinity was consolidatErl. The re.rraining natural patches in the corridor were investigated and connections between the region selected and other protected areas were noted. Most analysis \'.aS done from aerial photos and information provided in the South Platte River Major Drainageway Plan ( UDFCD 1984) . This information was used to select areas meeting criteria described above; sites were visited, and an area selectErl. IDENTIFYING IMFDRTANT HABITAT AREAS WITHIN THE RffiiON Information about bird habitat specific to the designated region is rae1er sketchy and derived primarily from conversations with Colorado Division of Wildlife employees and many individuals familiar with birds along the South Platte. The most illlfX>rtant habitat areas for resident and migratory birds within the general vicinity are Chatfield Lake/Arboretum and South Platte Park areas at the southern end of the region and Barr Lake, located 3 . 5 miles east of the river, at the northern end. Over 130 species of birds have been recorded at the Chatfield Arboretum and 297 SJ?2cies recorded at Barr Lake . These areas offer a diverse combination of grasslands, forest, lakes, and wetlands, and are appealing to many species. OrnitholDg"ical records are available of the Barr Lake area and_ nearby South Platte River corridor as early as 1909 (Hersey and Rockwell 1909). Barr 35

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Lake State Park currently attracts many birdwatchers because of nesting bald eagles and the heronry located on a peninsula at the reservoir. Other species of enjo yment such as American white pelicans, Swainson's hawks , night herons, and other birds are abundant at the park. Other important nesting, feeding, arrl resting areas are shown in figure ll. These are important areas because, although they hav e been affected by grazing or gravel mining, they still have stands of riparian or wetland vegetation. The South Platte River Major Drainageway Planning effort of 1984 divided the river corridor into eight reaches from Chatfield Lake State Recreation area to Baseline Road in Brighton and provided an inventory of development, parks, recreation, and open space along the corridor. In analyzing these eight reaches f o r habitat provision, large areas that provide little to no bird habitat became obvious. Along the southern stretches of river, Chatfield Darn State Recreation Area and South Platte Park provide important, fairly consolidated avian habitat. North of South Platte Park through the heavily-urbanized Denver area, however, large wetland/wildlife observationoriented parks are non-existent. The Adams Count y Regional Park is the next largest park-1 ike setting to the north, but the nature preserve is just a snall portion of this golf course/fairground/ carnr:ground/equestrian complex . Areas shewn in figure ll were selected for investigation because of their relative uniqueness. Dave Macintosh's dairy will likely be the only unmined or unconstructed "natural" patch l eft along the South Platte River between South Platte Park arrl Veteran' s Park/ Smith Natural Area in Brighton, a distance of 35 miles. The dairy is notable for its large cottonwcx::>d stands, its natural flooding regime , and it provides good nesting habitat for great horned owls , hawks, and other species (Macintosh, pers. comm.). No hunting is permitted on the dairy . 36

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Pt1tl:'NT !PiFigure 11

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The Smith Natural Area was donated to Brighton by Morgan Smith in the 1970 ' s for us e as a wildlife observation area. No gravel mining or hunting can take place on this property . The Smith family also owns property on the west bank of the South Platte and is considering donating this remnant stand of mature cottonwoods to the city as w ell (Longhurst pers. camm. 1988) . The natural area is characterize d b y a few wetland stand types and is adjace n t to the Mccann Ditch and the east bank of the South Platte River. Within the last three years, the east bank of the South Platte has been stabilize d by the addition of sidewalk riprap topped with fill dirt. The adjoining Veteran' s Park was originally a landfill and later d eveloped in the 1960 ' s into a r est stop for highwa y vehicles. Another significant remnant riparian patch is the area now knOND as Branley Lakes southeast of Brighton ( figure 11 ) . Old rive r meanders, mature and rege n erating cottonwood stands , and proximity to Barr Lake and the Smith Natural Area/Veteran' s Park are a make this an important habitat area, especially for bald eagle s that feed on wintering waterfONl along the South Platte River (Lovell pers. camm. 1987) . This area will be mined for gravel over the next 20 years, beginning in 1988 . Once mining is canpleted, the land will b e reclaimed for wildlife habitat and recreation and managed b y the City of Brighton. SITE SELECI'ION With South Platte Park providing impo rtant r esting, breeding, and wintering habitat along the rive r to the south o f Denver, it becam e clear that an equivalent are a was needed t o the north to conn ect to Barr Lak e , Dave M3.cintosh ' s remnant habitat patch, and the Adams Count y Regional Park. _I:X)V.l reccmnend e d that the best site to d esign bird habitat and a wetland mitigation area would be on an SO-acr e are a adjacent to Barr Lak e (Lovell 38

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pers. canm. 1987). The site would buffer the heronry ard eagle nest from highway and other development. This site was considered but rejected because much of the tract is already a wetland, and because providing habitat along the South Platte seems more critically needed with pending mining and suburban develo:r;::rnent than adding to an existing protected area. Linkages from Barr Lake to a bird habitat area in this vicinity almg the South Platte would be critical to improving habitat in the region. Dave Macintosh's dairy was also considered. However it was rejected since, according to the owner, this site's preservation as it presently exists is assured by strong family interest in continuing the dairy operation. Adams Count y also is discussing conservation easements with the family as another option of preserving the patch in perpetuity. The Adams County Regional Park site was not considered further because of its size limitations. The Bromley lakes area is slated to be mined for gravel. Nonetheless, this appeared as the best site choice when connected with the Srni th Natural Area/Veteran's Park site, as it has the p::>tential to provide excellent spatial and tenporal variety, and iiTlfX)rtant linkages to Barr Lake and other areas could be provided. Thus, it meets all established criteria and provides an opportunity to work with gravel pit designers and adjacent landowners in creating a reclamation plan that would satisfy the goals of the bird habitat area. SUMMARY The terms region and landscape have been discussed to define the area considered by this thesis. Three landscape ecological concepts have been described in terms of their applicability to birds and humans ard applied in 39

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selecting the site. The site s elected meets the established criteria of spatial and temporal heterogeneity and the potential for interconnections between natural and recreational areas in the region. 40

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CHAPI'ER THREE: UNDERSTAND IN; THE SITE AND USERS AT THE LANDSCAPE SCALE INI'RODUCI'ION A site analysis must follow site selection before design can proceed. This chapter also explores concepts of landscape ecology as applied to site analysis. First, the site is analyzed in tenns of its canponents: geology, hydrology, topography, vegetation, and so on , with much of this information derived from the UDFCD (1984), except where otherwise noted. Information is t hen synthesized so tffit the site can be understood with regard to its structure, function, and dynamics. SITE ANALYSIS lOCATION The study area i s in western Adams Count y , Colorado, TlS-R67W, Sections l , 11, 12, 13, and 14, as shown in figure 12. It is adjacent to the City of Brighton to the east and is 20 miles northeast of Denver . M3.jor geographic features are the South Platte River and the adjacent uplands. Vie.vs of Longs Peak and Mount Evans along the Front Range of the Rocky Mountains are evident from the site to the west. The site is approximately 1000 acres in size and is about 2 miles in length and an average of l mile in width. M:ijor street access is l44th Avenue to the south, E . l60th Avenue (Colorado State H ighway 7) to the north, Miller Street to the east, and Riverdale Road to the west. The site is bordered_ b y agricultural and industrial landscapes to the north, south, and west, and by urban/ suburban landscape to the east. 41

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CLIMATE Local temperature and precipitation data is summarized in table 1: TABLE l : PRECIPITATION (SAMPSON AND BARBER 197 4) [Data for temperature and precipitation from Byers, Arapahoe County. Data on snow cover from Stapleton Airfield at Denver] Temperature Precipitation 2 years in 10 will have at 2 years in 10 will leas t 4 days with-have-Average Month Averag e Average number dail y dail y Average of days maximum minimum Maximum Minimum total with snow temperature temperature Less More cover equal to or equal to or than-than-higher than-lower than-oF. oF. oF. oF. lnehu Inehu Inehu January ______________ _ _ 43 14 61 -6 0. 43 0 . 1 0. 8 8 February __________ _____ 46 18 64 -2 . 47 .2 .7 9 March _________________ 52 23 70 4 . 87 .4 1.6 7 _________________ 62 33 79 19 1. 86 .7 2 . 8 3 ay _________ _ _________ 71 42 86 32 2 . 54 . 9 3 : 7 1 June ___________________ 84 51 96 40 1. 58 . 7 2 . 6 0 91 57 99 50 2. 01 1.0 3. 2 0 89 56 98 49 1. 49 .7 2. 1 0 September _______ _ _____ 80 47 94 35 1.14 .2 1.7 (1) October ____________ ___ . 69 36 83 25 . 72 . 1 1.5 1 November ______________ 54 23 71 7 . 54 .2 .9 5 December_ __ . _____ _____ 46 18 64 2 . 40 . 1 .6 7 Year _______ _____ _ _ 66_ 35 101 3 -14 14. 05 9 . 2 18. 3 41 1 Less than one-half day. 'Average annual highest temperature. 1 Average lowest annual temperature. Most flood events on the South Platte River are due to summer thunderstorm activity. Average annual precipitation is 14 inches. Sunshine occurs 69 percent of the possible hours of sunlight annually. Vegetation along the river corridor slows windspeeds, which primarily occur from the north and west, but generally the area can be very windy in areas where vegetation has been removed. Wind speeds are highest from December through March. GIDLCX;Y The lowest and oldest layers of rocks in this area are Mesozoic sedimentary rocks, which bend down into the Denver resin. Pierre shale underlying Denver formation sands and gravels comprise the next layers. The upper surface o f 43 Average depth of snow on days with snow cover Ineht1 2 3 3 ( 3 0 0 0 ( 2 3 3 3

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the Denver f orrmtion i s nON eroded by the South Platte River and tribJtaries, which have sculpted the hilly Piedmont surface on which Denver sprawls (Chronic 1980) . Within the study area, Pierre shale is encountered at a 20-70-foot depth (Tuttle et al. 1986 , UDFCD 1985) . Gravel deposits overlay the shale. The hydrology of the South Platte River from Chatfield Darn to Brighton has been reported in many sources, most notably the UDFCD plan (1984) . Although understanding the entire system is important to understanding the river s egment tet-ween E . l44th Avenue and E . l 60th Avenue , this report will s ummarize or incorporate the other larger-scale studies by reference and concentrate primarily on hydrologic characteristics in the project area v icinity that have an irnp3.ct on birds and people. G roundwater T he reach of the South Platte River included in the study area is fed by an alluvial aquifer called the Valley Fill Aquifer. The aquifer is a sand and gravel deposit, varying in depth from 10 to 30 feet. Groundwater is 2 to 5 feet below existing ground level. This aquifer is the water supply for the City of Brighton, which draws from a series of wells. Nitrate and sulfate levels are high in the Brighton well water due to farm runoff, and occasionally in summer, Brighton has "Water Quality Alerts" where infants and adults are advised to drink bottled water (Tuttle pers. comn. 1988) . Brighton is attempting to dilute polluted groundwater sources with better quality ditch water, but other approaches, such as filtering wBter through wetlands, have potential but have not been tried. The Arapahoe and Laramie-Fox Hills aquifers also underlie the study area and 44

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are separated from the Valley Fill Aquifer by a layer of Pierre shale. Average depth to water table is 5 to 10 feet in these aquifers tffit are adjacent to the Valley Fill Aquifer. Water table contours and wells in the area are shewn in figure 13. The water table slopes to.vard the river and dcwnstrearn. Gravel mining has had a number of effects on the water table. Where an open, flat pit has been left, the normal do.vnstream slope of the aquifer is disrupted; thus, the pit acts as a water table drain in its upstream area, and as a water table recharge zone in its do.vnstrearn area. Prior to mining, an acre-foot of gravel contained 0. 25 acre-feet of water as saturated aquifer. Rerroving one acre-foot of gravel results in an equal arrount of water moving into that space, increasing the amount of water in the gravelmined floodplain. It is important tffit wells in the vicinity do not experience drawdown as a result of gravel mining. wet gravel mining techniques do not result in significant drawdcwn since water is not rerroved. Surface Water For bird habitat design, water quantity and quality are of critical importance and the following data are of interest: overall surface water characteristics; floodplain delineation; high and low flows; historic configuration and the effects of Chatfield Dam on regulating flows; water quality; and sedimentation and erosion. Overall Surface Water Characteristics and Floodplain Delineation. Figures 14 and 15 provide an overview of the South Platte basin, major tributaries, and the floodplain boundary in the study area. The floodplain in the study area is essentially natural and unchannelized, although sidewalk piecesarmor the banks in many locations. 45

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frr 1\. ' ' ...... / , . L. • R67W f'--I (/ I I ' v fkjt'MtL . . . ....... BOUNDARY OF STUDY AREA e ... ..... . .. WELL / .. . . .. .•• ---?TUr:>yAee,.... .::::z::.. TUTTLE APPLEGATE RINDAHL, I Consult•nu for l•nd •nd ltHouru O....loptMnt (lq6 . Figure 13 GROlJNLWATER CONI'OURS AND WElLS

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' \ _,..-/ / Spronvs Reservo i r 10 0 I() 20 Stole '" M1ltt 40 Figure 14 8000 0 t4000 Scele .. , .. , Envle•ood Reservoir \ FLA.-n-E.

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---LEGEND 100•YEAR FLOOD BOUNDARY FLOODWAY FRINGE I'LOODWAY I'LOODWAY FRINGE APPROXINATE 100-YEAR FLOOD BOUNDARY . ! • I V / READY MIXED CONCRETE CO. BROMLEY LAKES FLOODPLAIN LOCATION MAP TUTTLE APPLEGATE RINDAHL, If:" ;-\t;;.( ) ............ .. -Figure 15 Fl.OJDPIAIN BOUNTIARY

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The study area includes part of the Mccann Ditch to the east and the Brighton Ditch to the west. The Brighton Ditch diverts irrigation water from the left bank of the South Platte River. A 44.80 cfs flow is the assigned water right as of 1883 . Tbdd Creek flows fro m the wes t into the South Platte River. Its 100-year floodplain width is 4080 feet and new developnent is not r;ermitted within this area (Moore r:ers . ccmn. 1988) . A small gravel pit on the west river bank is currently the only lentic water type in the study area. This po nd is roughly 200-feet by 60-feet in size and herons frequentl y use the pond . River Flaws . High f l o w s durin g the nesting season can negativel y affect birds if flood level s inundate river banks where kingfishers and other riparian species nest. The study area was severely flooded in 1973 by a flo w of aro und 33, 000 cfs during the 100-year storm. The recurrence interval of 2-, 10-, 50-, and 100-year flooo s south and north of the study area are shewn in table 2 . Lowest flONs ocrur during late s urmer and winter before snowmelt and thunderstorm activity and usually affect birds o n l y if fish and invertebrates are impacted by low flows . Kingfishers and herons benefit from lower flows since they prefer shallow-water fishing. TABLE 2 SOUI'H PLATTE RIVER FLOJD HYDROLOGY (FROM UDFCD 198 4 ) Discharge (cfs) Recurrence Interval Location 2-Year IO-Year 50-Year 100-year DIS Dutch Creek * * 5,060 6,400 S. Platte@ Littleton * 3,100 6,170 7,940 D I S Big Dry Creek * 4,350 9,600 12,600 DIS Little Dry Creek * 5,750 12,200 16,000 DIS Cherry Creek 3,580 9, 700 18,000 22,500 S. Platte at 19th Ave. 3,580 9,700 18,000 22,400 UIS Sand Creek 3,580 9,700 17,400 21,700 -D I S Clear Creek 3,550 13,000 28,600 38,000 D I S First Creek 3,550 12,700 27,500 36,000 S . Platte @Henderson 3,400 12,300 27,000 35,500 Base l ine R oad 3,130 11,400 25,500 3 3 ,600 * Snowmelt a n d D a m Releases P r e domi nat e 49

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Historic Configuration and the Effects of Chatfield Dam. The South Platte River has been described as "too thick to drink, too thin to farm, too shallow to sail on , too broad to shoo t a rifle across" (UCFDC 1984). In its pristine, intermittent state, the channel width varied from 1500 to 2500 feet across, with numerous deep channels (Knopf 1986). The river' s depth, sinuosity, and width depended on the sediment loads and water volurres fran its tributaries. Scouring actions fran uncontrolled flood waters kept channels clear of vegetation. The advent of irrigation and the construction of numerous ditches in the 1880's resulted in a higher water table in adjacent lands, the creation of a permanent fla.v, and the elimination of many secondary channels. The construction of four water supply reservoirs, three flood control reservoirs, many detention facilities, channelization, and other facilities have permanently altered the natural flow regirre of the South Platte River. Chatfield Dam, canpleted in 1975 , has an effect on the South Platte River. The dam 's primary function is flood control. Releases are regulated so that the f low at the Henderson Gage near Thornton does not exceed 5000 cfs. Average and peak runoff flc:ws are l01M2r than previous natural flo.vs; thus, the cycle of flooding and scouring during high flow periods has been drastically reduced. Water Quality. In the reach between Burlington Ditch and Brighton, fecal coliform, nitrogen compounds , copper, zinc, and iron concentrations all occasionally and sanetimes routinely exceed standards (UDFCD 1984) . In addition, the Metropolitan Denver S ewage Disposal District Plant and South Adams County Sewage Treatment Plant effluent releases result in elevated biochemical and chemical oxygen demand rates. Within the 40-mile stretch from Chatfield Dam to Brighton, water quality is poorest in the northernmost stretches due to farm runoff and sewage plant discharges. 50

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T h e nearest upstream poin t source of pollution to the study site is the South Marns Count y Sewage Treatment Plant (4 miles from Branley lakes) , which discharges approximately 2 . 4 million gallons/ day (MGD) of treated sewage into the river. No r:ermit limitatims exist for arnronia o r ph osphorous. In canpari son , the Metropolitan Denver Sewage D isposal Plant (lO miles upstream from Branley lakes) discharges 145 MGD into the stream. Thi s plant only recently has been re:::IUired to limit arnronia discharge s and has recently dechlorinated effluent discharges (Woodling pers. comm. 198 8 , French pers. comm. 1988) . Point pollutant sources such as treatment plan t effluent introduce higher organic material conce ntrations, which results in high densities of pollution-tolerant macroinvertebrates such as bloodworms , s l u d ge worms, and nematod e s flourishing instead of cleanwater organisms such as mayflies, caddis flies, and other invertebrate s eate n b y many birds (UDFCD 1984) . The limited food source s likely limits bird species diversity to some extent. Pos itive fish and invertebrate response resulting from dechlorination has been note d b y aquatic ecologists (French pers. camm. 1988) . Non-point source pollution results fran sediments, m etal s , and nutrients introduced into the stream b y stormwat e r runoff. In additi on , stormwat e r impacts sediments on the river bottom . River sediments are chemica l sinks or sources for metals and nutrients; the s e pollutants can be released d epending on the velocity and quantity of runoff. Following major storm events, total suspended solids, organic carbm, nitrogen, phosphorous , fecal colif orm bacteria, iron, mangan e s e , lead , and zinc increase substantially in the drainage , obscuring visibility for fishing birds. Same bird species are susceptible to f ertilizers and insecticide s that accumulate in their food , which affects their breeding success ( USFS 1981) . 51

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Stream-bank stabilization also affects water quality of the South Platte . Stabilization with riprap and other materials results in less streamside erosion and can be placed to provide habitat previously not available in the channel. Ho.vever, sed.imentation occurs during the construction period and disruption to sediments on the river bottom can result in resuspension of toxic contaminants. Sedimentation and Erosion. The average river bed slope from the mouth of Clear Creek to Brighton is 9 feet t:er mile. r::>otmstrearn from Brighton, the South Platte river is actively eroding its banks and moving laterally, especially at gravel point bars. The river rroves freely, resulting in a higher bank wher e the current is eroding the bank , and a lON bank occuring in deposition areas. Average bankfull depths are 8 and 9 feet. Between 1963 and 1983 , the South Platte River has eroded vertically by 4 feet in the Brighton area. Impacts from erosion include: exposing utility lines, bridge pier scour, caving river banks, erosion of trees and resulting debris, loss of agricultural land, breaching of gravel pits, lONered groundwater tables, and increase d channel capacity. Loss of nesting areas and bird habitat also results from erosion. SOILS/GRAVEL RESOURCES Soils Pliocene period g round surface elevations in the Brighton area wer e 1600 feet higher than present and eight cycles of erosion and filling have occurred since then, with a ninth currently in progress (UDFCD 1984). Surficial deposits are characterized by four soil types in the study area (figure 8): loamy alluvial land; moderately wet (Lw); loamy alluvial land, gravelly substratum (Lv); sandy alluvial land (Sm); and wet alluvial land 52

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(wt) (Sampson and Barber 1974) . The characteristics of each soil type are s1.ll'IIJlarized and map];Ed in Sampson and Barter 1974 . A large numl::er o f human-made surficial deposits occur in this area, notably the concrete and asphalt pieCEs along the South Platte banks placed for l::Bnk stabilization. Gravel Resources Mineral resources along the South Platte River are limited to high quality gravel deposits. The gravel is primarily granite, quartz, and pegmatite. Pebb les and granule gravel constituting about 50 percent of the deposit, and sand about 50 percent. Fines and oversize material generally are lacking. Cross-sections of gravel deposits in the Brighton area were made by Turner (1974). These crossections show that most of the extractable gravel is concentrated on the east side of the river (figure 16). Gra vel deposits have been mined extensively within the Denver metropolitan area, with most remaining deposits occurring in Adams County along the 2river corridor. According to Brighton city planners, except for the Veteran's Park/ Smith Nature Reserve, most of the South Platte corridor around Brighton will eventually be mined for gravel (Moore J;Ers . camm. 1987). Records collected in 1984 do not show future mining plans for the area J::etween Bramley Lakes area and Bridge Road (UDFCD 1984) , but the city has been contacted to negotiate with grave l companies for parcels within the study area . 'IOPOGRAPHY The study area is within the Colorado Piedmont section of the Great Plains physiCXJraphic province (Sampson and Barber 197 4) . The are a is draineci by 53

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I : '• 1 . \ .\ . . ,. , I . _..,_.,. \ . ' I . o ' . . \ . ' .. _. ' . \ J i . .I . . \ . , , , . . . \ .. \ . _ .......... SECTIONS A '

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the South Platte River system and is characterized b y broadly rolling topography and streams in bread valleys. The elevation of the study area ranges from 4970 feet above sea level at the Branley Lake site to 4955 feet at the Smith Nature Reserve. The river bottom is approximately 10-30-feet lower than the adjacent uplands and side slopes are moderately steep. The river valley in the study area vicinity trends in a northeast/southwest direction, but numerous meanders characterize the valley in this unrestricted section. Mcst slopes face northwest and southeast, with a few slopes facing east and west. Very few slopes have a direct north or south . aspect. VffiEI'ATION The vegetation of the South Platte River drainage has changed considerably since the late nineteenth century. Historically, the river was relatively straight, wide , and flowed only 4-6 months during spring and early sumrrer each year (Knopf 1986) . Now the river is one-fifth to one-twentieth of its original width. Irrigation agriculture initiated in the 1880's, involved ditch construction and impoundment of spring runoff, resulted in percolation of water through valley alluvium , causing the water table to rise to the point of sustaining a permanent, year-round flow in the river. River banks that wer e once continually disrupted by the constant shifting of the river channels, became relatively stable, although flooding and scouring regimes still occurred . Overflow chann els such as abandoned meanders and oxbo.vs served as "nursery bars" for hydrophytic species, such as sandbar willows. Willow stands became established since there was a constant water source, and became dense enough that they provided a barrier to floodwaters and reduced water 55

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velocities, causing sediment deposition. Cottonwood seedlings were established on these raised bars composed of fine sediments. When they matured, they shaded out the willows, and prevented much seedling regeneration of other species (Brady et al. 1985). With the advent of flocx:l control dams and stream channelization, overflow channels no longer formed. Shrub stands greatly reduced in numbers, and cottonwocx:l regeneration has been restricted. Riparian vegetation is still developing, however, with the spread of intrcx:luced species such as Russian Olive and tamarisk. Four broad categories of vegetation can be identified within the study area: upland cottonwocx:l forest, shrub-herbaceous wetland, agricultural, and grasslands. Within these brood categories, stand-tyr:es (sensu Marr 196 7) can be designated. Upland Cottonwocx:l Forest Cottonwood Stand-Type: Cottonwood stands daninated by plains cottonv.Dcx:l occur alc:ng former river meanders and oxbows . These stands are mature, ranging in age fran 60 to 100 years (usually the maximum lifespan of this species in this region) and there is little regeneration due to the absence o f flocx:ling and scouring regimes needed for seedling regeneration (Brady 1985). These mature stands provide seeds, buds, and twigs for wildlife feeding, as well as important nesting and perching habitat for numerous bird species, ranging from cavity-nesters such as v.Dodpeckers to colonial nesters such as herons. The understory of this stand tyr:e is generally limited to grasses, due primarily to grazing impacts. 56

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Shrub-Herbaceous Wetland cattail Stand-type: Wide sections of the Mccann Ditch in the Smith Natural Area/Veterans Park area are daninated by cattails. During Spring 1988 , however, it was noticed that large sections of these cattail stands appear to be victims of a muskrat eat-out. If this is the case, muskrats have eaten the tuberous base of the cattails and then built feeding platforms of the leafy rerrains. Small stands can be wir;ed out in a single season and muskrats then move on to other areas. The cattails can regenerate quickly from a few rerraining tubers if water levels remain stable (weller 1981). cattails are obligate wetland sr;ecies. Sandbar Willo.v-Tamarisk Stand-type: Isolated stands of these wetland shrubs are also present in the Veteran' s Park/Smith Natural Area and canprise about 90 percent of the total shrub layer in the 1 000-acre study area. Poison Hemlock / Canadian Thistle Stand-type: The water table is apparantly dropping in sane locations within the Veteran's Park/Smith Natural Area, typically identified by the dense influx of these two herbaceous species adjacent to a wetland (Cooper pers. camm. 1988). Agricultural Corn-Soybean Stand-Type: Farmers in the study area currently plant east-west or north-south-oriented crops. Creps are sown in April or May, harvested in late summer , with stubble standing over the winter. Winter cover crops such as winter wheat are sometirres planted. Grains provide a food source for geese and other seed-eating birds, as well as rodents. Grasslands Smooth Brane-Timothy Stand-Type: Pasture grasse s have been planted in 57

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fields throughout the study area to increase species for grazing ln the native short-grass prairie ecosystem. Buffalo Grass-Blue Grarna Stand-Type : Some grazed areas are still daninated by these native short grass prairie species. Barnyard Grass-Ambrosia Stand-Type: Areas that have been scraped, trampled, or ccmpacted due to gravel mining and other types of disturbances are dcminated by numerous annual herbaceous species that provide irrportant food and cover for birds and small mammals. WILDLIFE Birds Many bird species on the Barr Lake Bird Species List (n . d.) are likely to occur only rarely along the current configuration of the South Platte River in the study area. However , as gravel pits are created in the future, more of these lentic and wetland species will likely be attracted and therefore species from Barr Lake are considered to be bird species of the study area. Targeted species and their associated guilds (appendix A) have been identified for design purposes and are described in the following chapter under "Key Users." Prime feeding and breeding habitat in the existing study area, the existing proposed developnent scenario, arrl the desired development scenario are compared in chapter four. Mammals, Reptiles, Amphibians , Fish, and Invertebrates The has identified the following key species present in the study area: 58

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TABLE 3: CCMMJN WILDLIFE SPECIES IN THE STUDY AREA ('IUITIE APPLffiATE RINDllliL, INC., 1987, FRENCH PERS. CCM-1. 1988) Mule deer White-tailed deer Red fox Raccoon Skunk Beaver Prairie dCXJ Mice and other small rnamrrals Bullsnake Plains garter snake Cammon garter snake Tiger salamander Painted turtle Northern leopard frog Bullfrog WOodhouse's toad White sucker Green sunfish Yellow perch Largemouth bass Cammon carp Longnose sucker Sand shiner Fathead minno.v Mosquito fish Long-nosed dace Brook stickleback Plains killifish Sludge worms BlcxXlworms Nematodes With the exception of red fox, rnamrrals generally have adapted well to edge conditions and the increasing influence o f humans . Deer are depending more on suburban plantings as food sources than ever before; skunks and raccoons opportunistically feed close to human habitation; and reaver are active in streams close to human habitation, as is the case at the Smith Natural Area. A large prairie dog tcwn is presently locate d within the study area. Prairie dogs and othe r small marnrPals are irq::ortant food source s for raptors, eagles, and owls. 59

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Many reptiles and amphibians are also food sources for a variety of large birds common in the study area, such as eagles, herons, raptors, and owls . Gravel lakes could provide habitat for an even greater diversity of fish, including minnc:ws whose natural habitat is declining due to W2tland destruction and stream channelization (Woodling pers. camm. 1988) . Many bird species feed on invertebrates, although reduced water quality along the South Platte in this section limits the species available for feeding. French (pers. carrn . 1988) reports that caddis flies and rrayflies could become numerous along the South Platte again as a result of sewage treatment plants dechlorinating effluent, but additional impacts resulting from proposed channelization would counteract this benefit. HUMANS Brief History of the Brighton Area Historically, Brighton's roots are agricultural. Beginning in the 1880 ' s , early settlers began diverting water from the South Platte and began farming corn and other crops. The cann ed vegetable industry was sparked by the advent of the railroad in 1908 , and is still a major employer in the Brighton area. Farms in the study area were established around 1910 . Existing Uses People currently utilize the study area for agricultural uses, grazing, horse excercising, junk storage, recreation, and wildlife observation. They travel four major corridors, Riverdale Road to the w est, l60th Avenue to the north, E . l44th Avenue to the south and the South Platte River. Adjacent_ land uses include housing subdivisions, two cemeteries, horse boarding, a playground, farming and ranching activities, and a sewage treatment plant. 60

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Planned Future Development Majo r growth f actors affecting the region and creating demand for grave l resources are the proposed new Denver rretropoli tan airport, to be located near Barr Lake , and E-470, a proposed toll road with a planned alignment that 'M:>uld cross about 3 miles south of the study area. tw transportation developments such as these result in associated housing and commercial development . If the new airport is built south of Brighton, a 3 to 6 percent growth is projected for the Brighton area, as opposed to the current l percent and under growth rate currently experienced (Moore pers. canm. 1988) . A 157-acre planned unit development adjacent to the Bromle y Lakes gravel mining operation is scheduled for development within the next 5 to 10 years and will consist of attached and detached single and multi-family residential units and a 10-acre park. On a larger scale, the Adams County Comprehensive Plan (1984) designates future uses of the study area to be floodplain, open sp:tce , and recreation. The more specific county objective for the study area is to: "restore the wildlife value of the South Platte River Valley after mining disturbance, and protect that value during subsequent redeveloprrent" (Adams County Ccrnprehensive Plan p. II-5). The resulting policy is to "encourag e environmentally sensitive designs for all types of developments that reduce f:Xlllution , take advantage ofexisting natural features, and create spaces favorable for wildlife" (Adams County Canprehensive Plan p . II-6). The Brighton Comprehensive Plan is currently in progress and will direct future development in a Kevin Lynch-oriented manner (1960) (see following section). The South Platte River Recreation Plan (UDFCD 1984) recommends that a linear park with regional or focal point p:trks be developed along the river within 61

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the study area. A bike, hike, and maintenance trail with an adjacent horse path v.Duld be constructed along the west bank, with proposed boot landings and chutes constructed along the west bank. Preserving and enhancing existing wildlife habitat is recomnended and creating new 'M2tlands is also recommended in abandoned oxbows . A channel engineered to acoammodate 10 -year flood events (riprap and vegetative bank protection) and floodplain management is recommended to stabilize eroding banks throughout most of the study area and the removal and relocation of the Brighton Ditch diversion dam is also suggested once the river is channelized to the UCFDC ( 1984) design. Along the west bank of the South Platte River, opposite Veteran' s Park, the plan proposes to construct a pocket park with 18-car parking and a boot landing. A pedestrian bridge v.Duld be placed to connect the west bank to the Smith Natural Area. The Bromley Lakes gravel mining plan (Tuttle Applegate Rindahl, Inc., 1987) involves excavating three 27-foot deep lakes (291 acres of water surface) in two phases, while maintaining the required 100-to 400-foot buffer between the lakes and river. The first phase involves setting up the plant, constructing an access road from Old Brighton Road, relocating portions of the .M:::Cann Ditch, stripping and stockpiling topsoil, and planting stockpiles to screen the site and prevent erosion. During Phase II, 15 acres per year will be stripped and excavated. Dikes between the lakes will accornrrodate an existing natural gas line and will be constructed at 3 : 1 slopes. The life of the mine is expected to be a minimum of 20 years. Most of the mature cottonwood s in the largest river meander would be preserved. The slcpe of the lake shoreline would be 3: l from .existing ground level to 10 feet belc:w the water surface. A 2 : 1 slope would be formed below 10 feet of the water surface to the bottom of the pit. Processing and 62

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batch plant locations would revert back to cropland according to the plan and three access roads v.Duld remain in place. The applicant will reclaim the land "to a state suitable for wildlife habitat" ('I\.lttle Applegate Rindahl, Inc. 1987). After mining is completed, the City of Brighton will manage the property and use it as a ccmnunity park. An overlay of probable future developnent and its relationship to prime bird species habitat is shown in figure 17. Brighton' s Image Brighton, to a visitor, is seen as a slower-paced, small agricultural to.vn . that, if winds are from the east, greets visitors with a whiff of livestock. To residents, the laissez-faire governmental attitude that allows rugged individualism is appropriate to their needs. However, proposed airport developnent and subsequent growth may change this image. The potential for increased growth has encouraged communit y planners to prepare the Brighton Comprehensive Plan and rally the community to identify what they perceive future image to b2. According to the planning consultant in charge of the plan, the communit y would like a more designed image in the future (&lyre pers. corrm. 1988). Slow incremental growth will likely be a thing of the past, and Brighton wants to establish a positive, landscape-oriented image for the rapid growth ahead. Planners have invoked Kevin Lynch ' s Image of the City (1960) to create the desired ambiance. The city is understood in terms of paths, activity centers, and districts, with corresponding scales of development for different elEment types. Brighton's terminology for structuring the urban landscape is compared to other systems, including landscape ecology's, in table 4. 63

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, I . ' ll rJ tl" l5eLl"eP nr c-ere r:_---• L,.ewtc;.• ' . . I •

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INI'ffiRATION OF SITE ANALYSIS INFORMATION ---In this section, the previously described site information is integrated so that the structure, functions, arrl dynamic qualities of the site can be understoc:rl . The structure of a landscape can be seen as repeated patterns of patches and corridors within a matrix. Species, nutrients, wind, water and energy flow in characteristic ways between these patches and corridors. Change also occurs in characteristic ways , as described in application to the project area. Each structural element, followed by a discussion on function and change , is described b y using landscape ecological terminology (Forman and Godron 1986). Landscape ecologists are not alone in their classification of landscape structure; several approaches from other disciplines are also presented. SITE S'IRUCI'URE, F'UN::TION , AND CHANGE Patches A patch is a "nonlinear surface area differing in appearance from its surroundings and often imbedded in a rratrix" (Forman and Gcrlron 1986, p . 212) Several types of patches have been described in the literature and occur in the study area. Disturbance patches are srra.ll areas disturbed in a rra.trix on a frequent or infrequent basis, such as areas that burn or flood regularly. South Platte River channels shift frequently and the river section in the study area is considered by the UDFCD (1984) to have serious river bank erosion problems . The flood control plan for this section is to line most banks with riprap and vegetation slope protection to prevent flooding from 10-year storm events. This will restrict natural erosion ana deposition regimes, and flooding regimes will be controlled by upstream dams. Therefore, disturbance patches resulting from flooding, once 65

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characteristic of the entire South Platte floodplain, are increasingly rare and soon TIB.y cease to exist. Remnant patches occur where widespread disturbance isolates a small undisturbed area. Old flood disturbance patche s resulting from pre-dam and chann elization flows, such as cottonwood forest occurring at river meand ers and abandoned oxbows, are evident throughout the river corridor. The s e can now be considered as remnant patches since they are not being replenished. In fact, as the area sustains rrore grave l mining , these patches will becane even mor e isolated and rare. Remnant patches, such as these cottonwood stands, often provide important wildlife habitat in an urban setting, and connecting these patches is important in reducing their isolation. The Smith Natural Area also is a remnant patch, embedded in a TIB.trix of agricultural and industrial disturbance. Introduced patches are created when organisms are introduced into an area. Introduced species often exert a dominating and continued effect and are the rrost widespread patches on earth. Most of the site is canprised of introduced patches. These are the agricultural fields, the bluegrass lawn of Veteran's Park, and the surrounding hanes and ranches. They are characterized by introduced species, such as cats, hybridized corn, and bluegrass, as well as by immigrating native specie s , such as starlings flocking at a farm or mic e rroving into horres for the winter. Thes e patche s characteristically require the use of fossil fuels to maintain them in a continually disturbed state than other patches. As described in chapte r two , patch shape and size are critical to understanding the function of the site . Previously rrentioned research by Schoener (1971), indicates that animals are attracte d to forms 66

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that flow perpendicular t o a travel course. Sorre of the cottonwcx:rl-forested meanders tffit are perpendicular to the river should be preserved for those reasons. Convergence lines occur at shelterbelt/ditch/ field intersections that may also concentrate animal occurrence ( Forrran and Godron 1986) . Important patches for bird habitat are slliT'Ilffirized in figure 18 . Corridors Corridors are narrow strips of land which differ fran the matrix on either side. Stream corridors border water courses and vary in width and gradient. Line corridors are narrow bands, such as hedgerows, paths, and drainage ditches, dominated throughout by edge species. The daninant stream corridor in the study area is the South Platte River corridor {figure 19). It is curvalinear (before channel stabilization). Breaks in the c ontinuity of the riparian vegetation-bordered corridor occur where fields and debris dominate the banks. The stream corridor functions as a conduit for water and nutrient flow, animal movement flow (for wildlife as 'Well as recreationists), and seed dispersal agent. It also functions as a barrier to smaller mammals . As mentioned earlier, its dynamic qualities are being reduced by channelization. Line corridors include the McCann and Brighton Ditches, Riverdale Road , E . l60th Avenue , numerous farm roads and property boundaries, powerlines, two hedgerows, and two distinct cottonwcx:rl-lined abandoned river meanders, which essentially form a curvalinear hedgerow . The two hedgero.vs were planted along field edges to block winds, and are characterized by low species diversity and relative hanogeneity in horizontal and vertical structure. Hedgerows serve i!Tip)rtant functions in the pasture/agricultural setting. They provide access for two out of three 67

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I I . J . I I . I } / I I •r I r-. .. ---------. ..J Figure 18' I . I I I I . ,...J I /._. / ( /

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() I ( . I < " I I I , -I . ( " " / "" . / . ( , I . L.._. / / , J

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lowland terrestrial birds and mammals to food in adjacent fields, as well as provide shelter from predators (Forman and Godron 1986) . Hedgerows also reduce the eroding effects of winds , and create a cooler, more humid microclimate on the leeward side. Evapotranspiration is greater than from the adjacent fields, but reflection of light is reduced in hedgerows (Ryszkowski and Kedziora 1987). Avian diversity is relatively high in hedgerows for feeding and breeding and hedgerows are of critical importance in a landscape with few woods, since forest species may be limited only to hedgerows . Connecting forest patches, such as riparian forest growing along the South Platte, with the two hedgerows may serve to increase critical wildlife habitat for forest species in the study area. M:l.trices A matrix is the most extensive and connected part of a landscape. It can be seen as the cement that surrounds independent elements, such as patches and corridors, with the area of the matrix exceeding the total area of any other landscape element type present. Thre e characteristics of a matrix are: relative area occupied by each landscape element types, the level of connectivity present between landscape elements, and the degree of control over landscape dynamics. In the study area, the highly modified agricultural fields are the matrix in which disturbance and remnant patches and stream and line corridors are imbedded (figure 20) . However , according to plans and predictions, this will change in the next 50 years as the matrix in the study area becomes gravel pit lakes. The stream corridor will remain , but line corridors will be dominated not by hedgerows and river meanders but by the 100-to-400-footwide mand9tor y buffer between the river and the lake , and b y pipeline corridors that separate gravel pit lakes. Thus, the gravel pit lakes will compris e a large area and 70

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(b lMru:TANT t?\-rr.H Figure 20 MATRIX

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will be the rrost connected landscape. Since natural succession will be thwarted by the deep, groundwater-filled lakes and lack of flooding, the matrix will exert a greater degree of control over landscape dynamics than the previous agricultural landscape or even a natural landscape. This is a critical point. Because the gravel pits are unsuitable for agricultural, urban, or suburban developnent, they could becane abandoned areas in the middle of expanding urban land. Yet they have the potential for serving as rich wildlife habitat or as a water-oriented recreation resource in an arid envirorunent. If gravel pits will become the future matrix, they must be designed so that they will serve a useful future purpose. Understanding patches, corridors, arrl matrices, hew they function arrl change, is a way of seeing the landscape in a horizontal way, as if looking at a landscape from an airplane or as a bird 1 ooking for shelter. Many questions about horizontal configurations are still unresearched; for example, what is the optimal width of a corridor for providing shelter and connecting remnant patches? What is the preferred distance between natural remnant patches for migrating birds? Is it better to have a number of tiny stepping-stone patches in a human-disturbed migration route, or a variety of patch sizes and shapes? Perhaps creating corridors as tendrils will encourage species into a particular area where people can watch. Research is only beginning on these subjects arrl although it is known that sane species rEquire heterogenous landscapes to satisfy habitat requirerrents, it is unknown haw large a patch should be, or hew wide a strip corridor is preferred by certain species, or how close one landscape element should be to another. Again, experimentation is the suggested route at this stage of the field. 72

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CUVfr'At
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-raJpJL.. : , : u r:>ue;-it'nvG l-4-tl'"f"' (flfttv t '1 e&) : i ff;:U5e : /1E'A(A1fCJ?NTCf, I HOt-'( 6l!!tXIND UNl:!! I ' i ! i I

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them in desireable situations, such as along the north edge of an agricultural field th:l.t connects to a stream corridor. Likewise, hedgero.vs would not be used in undesireable locations, such as where snow blocked b y the hedgerow will bury access routes. Specific applications of these concepts are shown in the following three ch:l.pters . 75

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CHAPI'ER FOUR: SITE DESIGN INI'RODUCI'ION This chapter sets design objectives, identifies key site users and their basic requirements, and designs the site according to informatio n and concepts described in the previous chapters. The emphasis of the design is on reclaiming the mined site as an example for future gravel pits and creating connections between the gravelmined area and adjacent suburbs, agricultural areas, and wildlife areas. DESIGN O :s.:rn:::TIVFS Design objectives originate from the overall site objectives discussed in chapter one and are further defired by Emphases of landscape ecology on spatial and tanporal heterogeneity and linkages discussed in chapters two and three. Objectives will be rret through site design and through emphasizing coordination with adjacent property owners . Five objectives are: l. Connect important patches with corridors to provide linkages within the site and to connect it with other imp::>rtant habitat areas in the region; 2 . Utilize research on patch shapes to create rich, varied areas for high bird species diversity and to create interesting spaces for people to enjoy; 3 . Increase quality and quantity of habitat for targeted bird species, their associated guilds, and watchable birds in general; 4 . Design a sequence of plantings so that patch configurations, corridors, and wildlife habitat for targeted species and guilds can be maintained o ver the long and short tenns; and 76

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5. Design areas that are enjoyable and educational for visitors and adjacent residents. Do this in a manner that creates a balance retween bird habitat requirements and people's environmental and socio-economic needs. KEY USERS BIRDS Although a goal of the design is to create habitat diversity to attract as many bird species as possible, it would be impractical to design for each of the 300 or more species that presently or potentially could use the site. Based on discussions with local ornithologists and review of DOW's Species of Special Concern list (1985) and other literature , the design will consider the habitat requirerrents of six bird species for the reasms shONn in table 5 . TABLE 5 : TARGEI'ED SPECIES Species Name: Great Blue Heron Belted Kingfisher western Grebe Lewis' Woodpecker 77 Reasons For Selection Very sensitive to disturbance (Vos 1984); high-profile bird with public which enhances preservation interest (DOW 1985); data available (Short 1985) Species of enjoyment; data available (Prose 1985) Declining species; nesting negatively affected by fluctuating water levels in artificial water bodies (DOW 1985); data available (Short 1984) Population decline due to competition with starlings and habitat destruction (ross of snags) (DOW 1985, Figgs, pers. camm. 1987)); data available (Sousa 1983)

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Cammon Yellowthroat Yellow Warbler Population decline due to marsh drainage (DOW 1985) Population decline due to heavy BrONnheaded Cowbird parasi tisrn ( JXM7 1985); data available (Schroeder 1982) The targeted species represent a range of species using different types of habitat in a riparian eoosystern . In providing habitat for these birds, many other birds with similar feeding and breeding requirements will also be accorrrnodated. These aggregates of species are known as guilds (Short 1983, Short in press). According to estimates, if the following conditions described earlier are met: habitat for species is present, canpetitive pressures are low, and a colonizing source is present (Roth 1976), then approximately 180 species comprising guilds for targeted species would likely utilize the area, as well as other birds migrating along the South Platte corridor and in the Barr Lake vicinity. Designing for these six species rray not provide enough habitat diversity to attract same upland bird species or winter residents. 'Ib meet the objectives of attracting high bird species diversity for people's enjoyment , those non-specific birds that could generally be attracted to diverse suburban gardens or agricultural areas are also considered as targeted species. PIDPLE The following user groups would be expected to use this study area over a 50+-year timeframe: Birdwatchers School children and teachers Recreationists (rafters, canoers, joggers, swimmers, sailboarders, bicyclists) Families 78

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Local teenagers Senior citizen groups Mining canpanies Farners DFSIGN PRcx;RAM BIRD HABITAT RB;)UIREMENI'S In this section, prirre habitat needs for targeted st:ecies will be surnrncrrized as they are pertinent to future study area design. The u.s Fish and Wildlife Service Habitat Evaluation Procedures Group has synthesized biological and habitat information published in the scientific literature as well as unpublished information reflecting the opinions of experts on five of the six targeted species. These sources (Schroeder 19 82 , Sousa 19 83, Short 1984, Short 1985, and Prose 1985) and others (Stokes 1979, Hancock 1984, Vos 1984) should be referenced for further detail. Existing prime habitat for targeted species is shown in figure 21. Great Blue Heron This species is camnonly seen in marshes, reservoirs, and streams. Shallow areas are needed for feeding and tall deciduous trees near water are preferred as colonial nest sites. These birds are sensitive to human disturbance, particularly mechanical disturbances entailing large machinery operation. Prime breeding and feeding habitat is canprised of the following elements (Short 1985): 1) Active or potential nest site is at least 0.6 acres in area, located within 825 feet of water, with nesting trees at least 15 feet high with sturdy branches cap3.ble of supporting nests. Trees rray be alive 79

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liit u ef,L;TE!J :)t GeS&E:. Ji! . . tt '1'eU..OW I • I • 1 . I . I I I I . J I . I . ' . 1 l . l . I • I I I . I . . I < r--J ' ' . ' Figure 21 '-., EX "'-/. PR. -' , / HABITAT . I , . } . I r L_J ./ / ,,,/ LILrl o z.-...., .., ,.,..,,. ..-r

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or dead but must be o:t;:en enough to allow herons to freely enter arrl leave nests; 2) a disturbance-free buffer zone during the breeding season, February through August, of 825 feet over land or 500 feet over water occurs around actual or ];X)tential n est sites; 3) distance between ];X)tential and existing heronries should be less than 0.62 mile; 4) foraging habitat is a water body tffit contains small fish, shallow water less than l to 2 feet deep, arrl a firm substrate ; 5) a disturbance-free zone up to 300 feet occurs around ];X)tential foraging areas; and 6) the foraging area is free from human disturbance for at least 4 hours per day ( 4 hours following sunrise or preceeding sunset) . Belted Kingfisher The belted kingfisher is a bird of stream courses, lakes, and ];X)nds which feed primarily on fish, which they catch in clear, shallow waters that are not overgrown with thick vegetation. Nests are excavated in vertical cutbanks of relatively friable soils. Prime breeding and feeding habitat is comprised of the following elements (Prose 1985): l) a minirrum habitat area is within 3500 feet from the edge of a water body ; 2) :t;:erches should be 2 00 feet from the water's edge and located in an area where the water is less than 2 feet deep and l::etween 30 and 70 percent riffles; 3) one sui table perch should be evenly st=aced and located every 80 feet; 4) the top 6 inches of water, where most fish are caught, must be relatively clear; and 5) there must be suitable, friable soil for burrow excavation ( 70-96 percent sand and less than 15 percent clay) . Thus, the design for belted kingfishers would strive to place evenly-s:p:iced perches within 200 feet of the river or gravel lakes, where the river has between 30 arrl 70 percent riffles and the water is less than 2 feet deep. Gravel pit banks are corrrnonly used nest sites (Bull 1974) and additional nesting habitat would not need to be provided. 81

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Western Grebe This species prefers to feed and breed on large marshes or reservoirs with large supplies of small fish. They nest on the water surface layer and feed within the water surface and water column layers. Pr.ime breeding and feeding habitat are ccmprised of the follo.ving elements (Short 1984) : l) a wetland/reservoir greater than 50 acres; 2) the presence of srrall fish ropulations; 3) sheltered coves with herbaceous wetland vegetation adjacent to open water (70 percent of the water body should be free of vegetatim, within the 30 percent of the water body that sustains wetland vegetation, wetland plants should be interspersed with open water as much as {X)SSible) ; 4) vegetation protection from large wakes that destroy nesting platforms; and 5) sustained water levels greater than 12 inches deep during the nesting season. Lewis ' Woodpecker This woodpecker inhabits open forest stands and feeds prirrarily on insects from spring to fall and on rrast (acorns) and corn, preferrably left standing or spring-plo.ved, during winter. Destruction of winter habitat represents a greater threat to the species than loss of breeding habitat because of the mor e specialized winter feeding requirements (Sousa 1983) . Because the birds are op{X)rtunistic feeders, no minirrum critical habitat areas can be designated. Prime feeding and breeding habitat requirements are as follows (Souse 1983) : l) Large canq::>y trees should be present, with retween 30 and 75 percent canopy closure; 2) at least one dead snag per acre should be p.resent for cavity nesting and ma.st storage; and 3) distance between winter food source (oak trees and standing corn crops) should not exceed 0.5 mile . 82

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Common Yellawthroat The yellcwthroat is a small warbler associated with wetland areas. They feed for insects at the water or mud surface and construct nests on the ground or on aquatic vegetation slightly above water level. Dense shrub or herbaceous wetland vegetation is required for concealment. Prirre habitat requirements have not been researched as thoroughly as the previous species. Minimum habitat area is 1.2 acres, that includes v.etland areas of dense errergent vegetation, such as cattails, arrl stable water levels. An insect source also is necessary (USDA 1981). Yellow Warbler These warblers require riparian areas for foraging and nesting, preferring areas of low deciduous growth, such as willows and alders. Nests are generally placed in shrubs 3 to 8 feet above the ground. Males sing from exposed perches. Yellow warblers are reported to prefer edge habitats and territory size is around 0.4 acre. Prine breeding and feeding habitat requirements include the following (Schroeder 1982) : 1) At least 0 . 4 acres of suitable habitat must b e present; 2) deciduous shrub wetland vegetation must be the daninant stand-type since yellow warblers only occasionally use cottonwood forest stand-types; 3) opt.irrel shrub densities are between 60 and 80 percent crown cover; 4) shrub heights should be 6.6 feet or greater. General Bird Habitat Requirements The basic habitat needs are food, shelter, and water. Many books have been written on attracting birds to backyards, and the golden rule seans to be: provide as much habitat variety as possible. Gustav Swanson, noted bird 83

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habitat observer, recomnends that wate r i s a critical e lerrent arrl should be emphasized and provided in varying depths so that it is "knee-deep" for all birds (Swanson pers. canm . 1987) . Water quality is also of concern since many invertebrates that are important bird food sources rray not tolerate the levels of pollutants present in rivers and aquifers in the study area. By varying horizontal proximity of landscape elements and by adding a variety of vegetation layers, many non-targeted birds will be attracted to this site alo ng a rrajor migratory corridor. B y creating fB.tterns and shapes that are perceived by birds flying o verhead as providing the possibility o f food, shelter, and s uitable nesting sites and materials, then increase d bird specie s diversity should result. In wetland ecosystems, bir d species richness is related to are a of open water and the interspersion of open water and dense cover (weller 1981) . wel lers' exampl e s suggest that the highest numbers of species occur in areas with 50 to 75 percent open wat e r and 25 to 50 percent dense W2tland vegetation occuring in srrall pools. Complexes of wetlands increase specie s richness o ver solitary wetlands of similar sizes (Brown and Dinsmor e 1986 ) . Gra vel lake d esign should incorporate this interspersion of deep and shallow areas into reclarration plans . The South Platte Riv e r is aligne d with the annual north-south bird migrations and provide s refug e and food to break the journey over unfavorable t errain and allows forest bird specie s to cross through grasslands (Sprunt 1975) . Therefore , forest corridors should be provided t o provide habiat for migrating forest species. HUMAN REQUIREMENTS Visitors to a bird habitat are a along the future gravel-pitted South Platte corridor will also hav e horizontal and v ertical SfB.tial n e ed s that should be 84

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accommodated. According to Simonds' (1983) previously mentioned ideas, birdwatchers and schoolchildren would generally appreciate a diversity of places and views in close proximity to maintain interest. Horizontally , this may mean walking along connecting corridors through a variety of patches. Vertically, it may mean being at eye level with shrubs for shelter at one point, and high above rreado.vs or fields for perching at another point. Feeding would take place at sheltered areas with views . Suburban users may require the enclosed, volumetric space that "supplies the elemental animal need for territory" that Condon (1988, p. 33) describes, canbined with less spatial enclosure in carm:m o;;::en spaces. In addition to physical requirements, humans also require cultural benefits from expending time and energy in a place. A sense of rreaning and connection with the rest of the world or perhaps an increased sense of awareness or even a sense of competitiveness in the world of "bird-getters" or life-listers. These are requirements that the designer must conside r in arranging physical elements on the site and in interpreting than. The site is within the Denver metropolitan area and is close to lodging , food service, and camping facilities; therefore, overnight facilities and food service will not be provided. Since the land considered (except for the Veteran's Park/ Smith Natural Area) is potentially valuable for gravel resources, unmined land would not be considered for permanent structures such as rest roams. The design should incorporate the following elements: * * * * * * * * Entrances Trails Interpretation/Orientation Observation Blinds Shelter/Nature/ Community Center Restrooms Parking Grave 1 Mining 85

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MASTER PIAN Landscape erological concepts have been woven together with the bird habitat and hunan use requirements to form a rraster plan. Physical elements, such as gravel lakes and trails, were designed b y drawing fran the concepts of providing spatial and temporal heterogeneity and c onnections to meet bird and human requirements. The design is presented (figure 22) along with sections (figures 23 and 24) and scherratic diagrams (figures 25, 26, and 27) to summarize and visualize haw these concepts were used. Habita t improvements are shown in figure 28, and are compared to existing and probable develo pment scenarios in figure 29 . Element locations are conceptual and need to be verified b y soil and groundwater testing to determine precise locations of designed features. GENERAL MASTER PIAN ATI'RIBt.JI'ES This plan features a canplex of large and srrall lakes, numerable wetland areas clustere d along sculpted lake edges and in shallow scrapes, and corridors of layered, open forests and shrubs. Corridors are preserved and reinforced alon g the South Platte River, and are created to connect important patches within the site and outside the s ite, such as cem e teries , farm shel terl::el ts, suburbs, creek drainages, and Barr Lake . They are prominent features of the design that extend the influence of the naturalistic area. Contiguity with the South Platte River trail system as well as with Barr Lake State Park is a connection of benefit t o Denver area recreationists. Spatial variety is provided on a horizontal and vertical basis, by creating bird-attracting and human-pleasing patterns with vegetation and b y layering vegetation to increase habitat niches and visual interest. Finally, because gravel pit development will take place over a 86

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!M f'al.K:U..Tl.F-/'L. ago "Tl:lWe2 [I] JjiiJ -Tl!l"'lt.. cme--[Q] LJ'1Z,Ge

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50+-year time frame, depending on demand for this resource, vegetation will achieve temporal diversity by virture of being planted at varying intervals over time. In addition, existing mature canopy trees will be replanted with other canopy trees in similar patterns so that existing corridor configurations are maintained. This staggered planting scherre coupled with the river shifting in same locations (permitting riparian vegetation to reestablish), will allow this design to maintain its integrity over time. NATURALISTIC FEATURES Gravel Lakes This plan shows considerable variation in the sizes and shapes of the gravel lakes. The smallest lakes occur to the north and are separated by dikes that would vary in width and in configuration to offer a variet y of views and contact with the lakes, adjacent vegetation, and birds. Although the TUttle Applegate Rindahl, Inc. plan for Bromley Lakes has been approved and excavation begins in 1988, it is proposed that plans be amended to reduce the size of the proposed lakes, create islands, and vary the lake edges to a more significant degree . The numerous, arroebic wetland edges create coves for wildlife feeding, nesting, and resting, which, of the targeted species, is especially valuable for western grebes. Habitat for endangered small fish species such as the northern red bellied-dace can also be provided along these sculpted edges (Woodling, pers. camm. 1988). Islands are designed to provide additional cover/water and marsh upland edges, which can increase population density of same bird species (weller 1981). Extensive shallow areas are d esigned with side slopes varying from l 0: l to 4: l to support a variety of water depths 88

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. . .. . .., . ... : . UP!.ANP , ... 40' Figure 23

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and wetland plants, which would be beneficial to all targeted species except Lewis' v.DOdpecker. This begins to approximate Weller's recornnended i nterspersion rate of 5 0 to 75 percent open water with 25 to 50 percent dense, clustered wetland areas (Weller 1981). Shallow scrapes appear in two designated areas, entailing rEfOC)ving vegetation and soils until contact is made with the water table, a depth of 2 to 5 feet. The scrapes are maintained at 6-inch t o 2-foot depths and planted with a variety of wetland plants. Again, all species (except Lewis' Wcx::dpecker) would benefit fran the creation of sha.llow wetland areas. The east end of the lake adjacent to the proposed h ousing subdivision is developed as a beach with sha.llo w slopes. Sailboard rental and other nc:::nrrotorized recreational activities take place from this point. Lakes serve as visual breathing roan in the plan to combat too much diversity in too small of an area, which could otherwise result in confusion or tension ( Sinonds 1983) . South Platte River In several locations, it is proposed that the river not be channelized according to the UDFCD plan; it would not be necessary because gravel lakes would be further away fran the river than the minimum 400-foot distance (Wright Water Engineers 1985), and it would allow some semblance of natural processes to take place. In these areas natural channel erosion and de_[X)sition would be allowed to continue until the river shifts to within 100 feet of a gravel lake. At that point, riverbank stabilization would take place. The benefit is that a wide river corridor would allow deposition of alluvium and the subsequent establishment of riparian vegetation, which 90

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otherwise would have to be planted to replace the ftmctions of existing decadent cotton'M:X:>d stands that are so important for herons, '.Deldpeckers, and kingfishers. Large boulders are placed in the river channel in three locations to create alluvial deposits and riffles where kingfishers and great blue herons fish. These boulders are strategically placed under perches that hang over the river. Ditches and Third Creek The Brighton Ditch remains unchanged except for relocation of the diversion darn if the South Platte is relocated from the existing location (UDFCD 1984). The McCann Ditch is changed considerably as it flaws through the study area. It is routed east of the gravel lakes and flaws between the subdivision and the lakes. The width of the ditch varies; in sane locations, it will be widened to create wetland stepping stones or larger wetland areas (described in more detail in the Smith Natural Area section to follow). Water shares may have to b e purchased to use water on-site (Tuttle pers. ccmn. 1988). Third Creek, which connects to Barr I.ake, is also widened to create connecting corridors for wetland bird species (figure 24). Vegetation Over the next 50 years, the study area could become a series of lakes interconnected with different types of wetlands and upland vegetation. Whil e native species should be used along the river corridor to prevent perpetuating the spread of non-native phreatophytes (water-lovingplants), non-native plants should be used in other locations to attract birds. Proposed wetlands, open forest, shrub, and agricultural plantings are designated on the master plan. 91

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l•aw Figure 2 4 E!!SPVR: L.At:.E: c..ot'-lNEC-TLON l11s'Z01 OPeN

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Wetl and plants are established alo ng the sculpted l ak e edges, along ditch and Third Creek drainages, and in scrape areas. Riparian W2tlands also rray became established in places where the river is not channelized, which may eventually replenish prime great blue h eron, kingfishe r , and Lewis ' woodpecked habitat. Eastern lake shores will require inmediate stabilization efforts so that plants are established before winds create banks too steep and erosive to support vegetation (Cooper pers. camm. 1988) . Different W2tland communities , ranging fro m shrub-dominated to floating plant-dominated communities are incorporated into the design. Existing cottonwood forest stand-types are supplemen ted b y plantings of deciduous c ano py trees, such as cottonwoods , hackberries (these trees attract insects, which may benefit Lewis ' w ocx:lpeckers , ye llowthroats , an d yellow warblers) , and oaks (fo r the mast-feeding Lewis ' wocx:lpeckers) . Most of the targeted species prefer openings in the canopy , so supplemental plantings should not create areas where closure is g reater than 70 percent (Sousa 1982) . Corridors of these trees also extend into the suburbs and into farm shelterbelts. Shelterbelts are designed for maximum bird species diversity. They are comprised of rnul tirc:ws o f deciduous and evergreen trees and shrubs, with open grassy areas between tre e and shrub layers (Schroe der 1986) . Thes e shelterbelts function to: 1) provide habitat for bird species; 2) create cooler, moister rnicroclimates as they slow wind and cause snow d eposition; and 3) create species mov ement corridors (Forrran and B:tudry 1984) • They also function in agricultural and suburban areas to create volumetric spaces and s erve as the "walls" of the "roans" created ( C ondon 1988). Presently , the shrub laye r is d epauperate in the stud y are a due to grazing and should be replanted to attract songbirds and other bird species. Alon g wetland margins and wate r course s , patche s of tall shrubs, such as sandbar

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willow, alder, red osier dC>g'\'X)Cld, hackberry, hawthorne, and chokecherry, are planted to provide concealment for common yellowthroats, nesting sites for yellow warblers, and stepping stones for the movement of these and other species. Open grassy areas occur in the Smith Natural Area , along E. l60th Avenu e and in adjacent agricultural pasture areas to add to the diversity of habitats provided, as well as to provide open spaces for vistas. It is important that agricultural land remain in proximity to this bird habitat area. First, corn crops, if not fall plowed , provide winter Lewis' woodpecker habitat along the study area edges. Secondly , agricultural uses are part of the Brighton tradition and image . Although as the area becorres rrore urbanized, property taxes may render farming econcmically infeasible, which means that farmland protection techniques must be pursued by farrrers and local governments to maintain this adjacent function that in inextricably tied to Brighton's image (Steiner and Theilacker 1984). The overall vegetation design strives to create shapes over time that are perceptable from overhead and that may serve to attract birds and people, such as peninsulas, perpendicular patches, and sculpted edges. Small and large stands of trees or shrubs should be planted at varying distances from each other to provide a variety of spaces for edge species (Wiens pers. comm. 1987) . The efficacy of these and other shapes in accomplishing their hypothesized task of attracting wildlife would be an interesting area for further study. Supplemental Feeding Areas Artificial feeding concentrates birds in a number of planned viewing areas near horres and the nature/ canmunity center. Traditional means including seed dispensers, suet, and hummingbird feeders, will provide year-round food sources for residents and migrants. 94

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Artificial Nesting Areas Birds, especially targeted species of concern, should be encouraged to n est in the study area. This nay entail constructing artificial h oles, nest boxes, or platforms that can be successfully used by woodpeckers , grebes, wood ducks, kestrels, a.vls, ducks , and double-crested conrorants. Many techniques are available for discouraging undesireable birds from using these nest boxes. For exampl e , holes in nest boxes for tree swallows can be nade too snall for starlings and house sparrow traps can be installed in other types of nest boxes (Kress 1985) . Protection from Threats Adjacent suburbs provide favorable bird habitat through ornamental plantings and bird feeders. However, numerous pet cats and dogs from the suburbs will likely prey on birds attracted to the study area. Encouraging neighbors to place collar bells on their pets is one of the only defenses against pet predation. The river itself also serves as a barrier to these pets, so that the west side of the habitat area would support a density of suburban predators. Much of the South Platte corridor is open to hunting. This sanctuary will be closed to hunting. Barr Lake and nearby hunting club properties provide alternative hunting opportunities. Use Corridors to Connect Other Areas and Cr eate Larg e r N e twork of Bird Habitat Areas Vegetated trail conn ections would be made from the study area to: Barr Lake Nearby cemeteries Adams County Nature Preserve 9 5

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Since these connections have greater implications for the regional scale, these are described in more detail in chapter six. CULTURAL FEATURES Entrances The site has four formalized entrances: l) local/regional pedestrians and bicyclists enter from the south by way of the South Platte River trail; 2) local users enter from the east through a community park located within the new housing subdivision; 3) local/regional users enter from the north at the Veteran' s Park/ Smith Natural Area; and 4) local/regional users enter from the Third Creek connection to Barr Lake. Entrance s to the bird habitat area will not be d ramatic points of chang e . There will not be a feeling of entering an isolated remnant nature preserve because the connectedness betwee n the habitat area and adjacent suburbs and agricultural areas has been carried through in corridor, shelterrelt, and ditch plantings. Wildlife habitat will be concentrated in the gravel lake bird habitat area, but, if suburban and f arm landscape design recommendations are followed, the habitat quality of adjacent develo pe d land will not be as stark of a contrast as retween traditional suburbs and gravel pits. Each entrance will feature orientation and interpretive signs to inform the visitor of the property 's purpose and important concepts (discussed later in this section). Trails The prirrary trail through the site is approximately 2 miles long and connects to the Adams Count y ped estrian/bicycle trail system along the South 96

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Platte River. The trail is adjacent to the river in all but one area, which is located on a narrow dike retween two large gravel lakes. There are two reasons for this: first, the trail then bypasses the patch with the highest heronry establishment potential and an appropriately wide buffer is provided over water (500 feet), so that the disturbance-sensitive great blue herons would not be impacted by use of the trail during the nesting season. This diversion away from the river also allows people to experience the feel of a lentic environment in the arid west by being in the middle of it, an unusual opportunity f o r non-boaters. Trails are designed as line corridors (or " r:aths " in Lynch ' s terms) that connect to diverse vegetation and water patches ( " n odes" ) of different ages, sizes, and types. People can experience a variety o f landscape elements an d features, such as the stonehenge-like circle of cottonwoods that was once a river meander ; lush, frog-noisy wetland scrapes, wide-open , blue lake vistas, a neighborhood beach peopled with colorful swimsuits and sailboards, a quiet eddy where chattering kingfishers hover overhead. A h ierarchy of trails would be provided that include the 6 foo t wide paved South Platte R iver trail, 5 -foot wide gravel trails connecting to the South Platte trail, and boardwalks or other raised walking surfaces that lead through wetland areas in the Smith Natural Area . At least one handicapped accessible trail is also provided with appropriate grades and materials. Social trails are inevitable, but would be strictly discouraged through potential nesting sites by planting dense , thorny shrubs. No formal trails are designed along the west portion of the site; this area serves as a bird sanctuary. Trails are strategically placed so that in sane locations, people are located retween major feeding and roosting routes. For example , the McCann 97

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Ditch trail is located along the edge of an agricultural field and a lake, so that the regular rroverrents of waterfowl and geese from the lakes to the fields and back can be easily observed. Birds may be encouraged to use trail corridors if feeding stations are provided along the trail. Artificial nesting areas should be provided away from trails so that nesting is not discouraged. Observation Blinds Blinds are important "landmarks" because they are located in bird-rich areas that offer covert viewing opportunities for visitors. They should be flexibly designed so that they can be moved. Lcx::ations for blinds can be peninsulas of land where wildlife should be rrore concentrated, near high rrovement corridors, near feeding areas, or near sculpted patch edges where wildlife activity is higher than lineal patch edges. An observation tower allows people to be above the site where landscape patterns are legible. Interpretation/Orientation Interpretive Facilities. Information is provided at entrances and along trails at interpretive nodes with two types of signing: informational and directional. Interpretive nodes, feeding areas, blinds, and other interpretive stopping places are located so that they are buffered from winter northwest winds and seating is designed so that a choice of shade or sun should be provided where possible. Railings, where used, should be spaced horizontally to allow handicapped people and children to see through. Interpretive Themes. Interpretation of a place is the ultimate synthesis of the landscape ecological perspective; in fact, Forman ( 1986) states that one 98

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of the most po.verful aspects of landscape ecology is "its straightforward language that enhances communication among decision-makers, the public, and scholars of diverse disciplines" (p . 78) . If this is true, then landscape ecology should be a powerful tool in designing an interpretive plan for this design. Based on personal observation in national and state parks, forests, wildlife refuges, and other nature preserves, interpretation tends to concentrate on traditional themes such as the classics: "The Web of Life" and "Use All of Your Senses" themes. Identifying plants and their historical or medicinal values is also popular. Barr Lake ' s visitor center includes fine displays o n animals: egg sizes and clues to bird identification. While these are valuable and necessary ideas and information that should be presented, interpretive therres c ould be taken one step further to use landscape ecological concepts. The following themes have been discussed earlier in this document's text as background for design. This provided information should be utilized on trail signs and /or in a visitor center with historical and recent aerial photographs illustrating a larger spatial and temporal perspective . * * * * * * * * * * People's and Arli..nals ' Reactions to Patch Shapes Edges and Diversity Corridors, Patches, Matrixes and their Interactions Guilds Heterogenous Loci Irrportance of the South Platte River Corridor: Structure, Function, and Changes in a Metropolitan Setting Wetland Functions in an Urban Setting Interconnections Between Urban and Natural Areas Role of Individual Hc:rnes and Suburban Developrrent in Providing Bird Habitat Role of Farms in Providing Bird Habitat Shelter Shelter is provided at the Smith Natural and serves as a starting off point 99

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and interpretive hub . The shelter would conceivably develop into a visitor center once mining is completed in the area. R estroams and parking are also located at this location (this is described in more detail in a following chapter). Building materials could include: rough lumber, wood siding and shingles, corrosive-resistant coated metals, solar heat, and glare-resistant glass. Emphasis would be on blending into the setting, rather than c ontrasting with the environment. Gravel The design must accommodate future gravel mining and assume that most land will eventually be mined , with the exception of the Veterans Park/ Smith Natural Area a nd land east of Riverdale Road and north of E. l60th Avenue , where gravel quantities are minimal . Future gravel mining involves the removal of bird feeding and breeding resources: agricultural fields and r iparian vegetation. Noise and human presence will increase during mining . Dust and emissions will also increase. Mitigating measures to reduce the impact on a developing bird sanctuary include the following points: * Mine sections adjacent to the river as early as possible. reclaiming river edge areas first, riparian forests and wetlands can get an early start on providing habitat and erosion control along the important South Platte migration route. * Preserve significant mature cottonwood stands, such as the notable abandoned river meander stands. These easy-to-see patterns can be an effective interpretive node . The mature trees also provide important habitat for cavity-dwelling and perching birds. Young cottonwood stands should also be preserved as much as possible since cottonwood regeneration is significantly reducing with increasing river 100

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channelization. These young stands will cmtinue to support birds requiring riparian forests after mature stands become decadent. * Create as few feeder roads for gravel hauling off of Riverdale Road as possible. The winding, narrow road presently has a distinct rural quality. In addition to the safety hazard of combining 10-20 cubic yard haul trucks with passenger vehicles, the heavy mining equipment using the road will cause rapid deterioration of the surface and result in road reconstruction, most likely to an upgraded size and capacity. The rural flavor would then be lost. SUMMARY Understanding site structure, function, and change is not only a good evaluative tool in the site analysis stage, it is also important at the design stage to predict the effects of a proposed design. For example , changing the study area matrix from agricultural fields to wetlands and gravel lakes will result in greater species flow toward the site because of increased heterogeneity. Variable patch e dges and connecting corridors will attract species to the area as well. Because of the vegetation variety in shel terbel ts and other patches and corridors, cooler, moister microclimates will be created that provide habitat for more species than the homogenous fields that lacked microclimates. Predators, such as cats, will increase as neighboring subdivisions are built and must be controlled by planned unit development regulations, restrictive covenants, or conservation easements, regulations, since habitat d esign will have only a minimal effect on this situation. Soil erosion into the river will decrease because the lake s filter sediments and wetlands filter nutrients and metals from lake and ditch water. Northwest winds will be buffered by multi-layered shelterbelts, 101

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also reducing soil erosion into the river. Thus, in this master plan, changing site structure will result in many beneficial functional changes within the study area. The master plan meets the major site objectives: to connect the naturalistic bird habitat area to other important habitat and recreational areas; to create varied patch shapes for bird species diversity and people's enjoyment; to increase the quantity and quality of targeted bird habitat; to provide self-perpetuating vegetation so that the design is self-maintaining; and to create an enjoyable, educational experience for people while meeting socio-econanic requirements. Figures 25, 26, and 27 s1...1!TUlarize ho.v the master plan meets the first four objectives using the form-generating concepts of spatial and temporal heterogeneity and connections. Figures 28 and 29 illustrate how improving bird habitat was achieved. The last objective is met by using Simonds ' , Condon 's, and Lynch ' s ideas of appropriate uses of diversity, creating volumetric spaces, and lending imageability by connecting important landmarks and ncx:les with paths (Simonds 1983, Condon 1988, Lynch 1960). Educational goals have been met through using landscape ecological concepts in interpretive themes. Socio econanic requirements are satisfied by realistically considering the future scale of mining, by creating an area that will increase property values of adjacent homes, and b y referring city officials and farmers to sources that have been successful in protecting farmlands on urban fringes (Steiner and Theilacker 1984). The design has further positive benefits than just those that meet stated objectives. For example, the site could be used in the future as a v.etland mitigation area. Whenever new construction impacts over l acre of wetlands, new v.etlands can be created at the expense of the developers. In this region, wetland replacement tends to occur in small, isolated patches 102

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J! i • I i I r-I I I I I I I I rJ ! EXISnNG / PRIME / HABITAT r / i ,/_7 / / u=u==1 ;.,! . ----lJU""'' i ........ . ---"' Figure 29pp:;!:JME: HJ6.51TAT

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instead of in c onsolidated, larger areas. If developers throughout the region were encouraged to concentrate wetland replacenent in this bird habitat area, then it would create a less fragmented area of more habitat value. Since wetlands a lso function to improve water quality by absorbing nutrients and metals, groundwater could conceivably be improved by concentrating wetland mitigation at this location. It Y.Duld also offset the gravel miners' costs to create the wetland areas shown on these plans (which they will think are excessive). Generating cost-benefit analyses, development performance standards, and zonin g recommendations wer e bey ond the scope of this thesis, but should be part of a future implementation strategy if this design is to becane a reality. 108

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CHAPI'ER FIVE: u::x:AL SCALE DESIGN INI'RODUcriON In this chapter the s_p3.tial, tenporal and connection concepts are carried through from the naster plan scale to local design scale. Three areas selected for more detailed design are: the adjacent subdivision (West Branley Lakes), adjacent agricultural larrl, and the Veteran's Park/Smith Natural Area. Design errphasis, again, is on providing bird habitat and socio-cultural benefits for visitors and residents. WEST BRCMLEY LAKES Three stages are involved in the design of this housing subdivision. First, alternatives are prepared at a l inch equals 200 feet scale that explore corridors, patches, and the matrix of houses and green spaces. Second, a neighborhood from the subdivision is designed to show connections between open s_p3.ces and houses. Finally, a planting plan is designed for an individual hane in the neighborhood that is structured and functions to provide bird habitat, energy efficiency, and enjoyabl e s_p3.ces for residents. SUBDIVISION SCALE West Branley Lakes is zoned as a planned unit developnent that has approved design regulations (Tuttle Applegate Rindahl, Inc. l987b) . Th e goals of these regulations, which include providing solar orientation for homes, designing neighborhoods , se_p3.rating pedestrians from cars, and providing visual and physical access to the gravel lakes, were utilized in creating the three alternatives in figures 30-32. Other "givens" in the 109

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design were the density factors of six units per acre, protnsed road and tract layouts, and the location of the carrrnuni ty park. Sul:rli vision alternatives demonstrate that concepts of structure, function, and change can be applied in designing low-density, single-family detached housing options for a minimum of 270 houses. Alternative A House Matrix/Grid This alternative features a matrix of hanes connected by variable-width line corridors of open space that separate contiguous backyards. One significant patch of open space is provided within three minutes walking distance of all horres and each house is located on a green finger of open space that connects to shelterbelts, the gravel lakes, or the carrrnunity park. MJst lots are aligned so that houses would maximize southern exposures and winds woul d be blocked by a major shelterbelt to the north. Species moverrent would be restricted to rather narrow corridors, which may impede the rrovement of sane animals, but should be adequate for woodpeckers and seedeating species, especially as planted trees grow older and taller. The design accomrrodates 280 houses, which would allow the developer a potential ten-house density bonus if more open space arrenities are furnished. Based on their writings, it would appear that Condon and Jackson would selec t this alternative over the other two because of "the grandeur of the grid" (1984 p . 64) as described by Jackson, and because grids tend to have clearer, more "defensible" boundaries between properties, which people prefer (Condon 1988) . Alexander (1977) would appreciate the accessible green areas within a three-minute walk. 110

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HOUSE MATRIX/ GFID

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Green Matrix/CUl-de-sac The matrix is open space in this alternative , with clusters of homes (figure 31). This design contains a variety of open space sizes which may allow for more species movements , including people; the connected green network is attached to each lot. Lots are not uniformly oriented, so not all houses v.:ould have southern exposures than under A . Srraller green spaces may be more difficult to maintain, although use of drought-tolerant plants would reduce maintenance requirements. This design accmm::x:iates a maximum of 275 houses. The green matrix would likely provide the best bird habitat, but it may be confusing to be in area with so many repeated clusters of homes . More distinctio n between housing clusters would create a more imageabl e pattern. Alternative C -Clustered Green Patche s This alternative combines elerrents of both the grid and the cul-de-sac design (figure 32) . Several considerable-sized and variable-shaped open spaces are within a 2-minute walk of all residences. Patches are close together, so corridors are shorter, but provide important connections for people and birds. Over half of the 270 lots are oriented for southern exposures and winds are buffered by shelterbelts. This alternative may be the most versatile and easiest to maintain. The variety of connected open space patches would provide the second best bird habitat of the three alternatives. Corridors are easy to follow, housing types are more varied than alternatives A or B, yet still legible. Properties have that "defensible" quality as well. This is the preferred alternative. ll2

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i . .. ,, t) 8 Figure 31 SUBDIVISION 8 GREEN MATRIX Z. 7J; ReOIPeNce::t '-JOft.n+ 0 lOO • tpo l""'U::O'

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I • I • , Figure 32 SUBDIVISION C CLUSTERED PATCHES -. ) .. s I

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NEIGHBORHJOD SCAlE From Alternative C , a section of homes has been explored in more detail. Figure 33 dem:::>nstrates green corridor connections retween open space patches. Individual owners will play an important role in augmenting the corridors and creating attractive streetscapes in their individual landscaping plans. Corridors of oaks arxl patches of conifers and berry-producing shrubs will lure birds into the suburbs for residents to enjoy. The corridors in this case could also function as barriers between private and public property, recommended by Condon. RESIDENI'IAL DESIGN SCAlE A house has been selected from the neighborhood to show the extension of corridors and the emphasis on spatial and tenporal variety in planting design for birds and people (figure 34) . In this design, habitat is provided for targeted species as well as general bird use. A snag , corn crops, and oak trees may attract Lewis' woodpecker. The pend that is located at a low sr:ot in the yard and is where a sump pump drains, circulates water for birds, perhaps even attracting warblers if other neighboring properties also design for bird attraction. Trees and shrubs with persistent fruits, such as hawthornes, mountain ash, firethorn, crabapples, and junipers can also temp t birds into the garden (Swanson 198 7 ) . The plan also shows that designing great bird habitat creates aesthetically varied gardens for year-round interest. The variety of vegetation and subsequent variety of motion, color, and form in birds gives the quality of surprise, curiosity, and induced movenent (Simonds 1983) . The space is mostly enclosed by trees and creates an outdoor room by the vertical 115

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-. ...-. ' \ .. . " Figure 33 '\ . . .. ./NEIGHBORHOOD 0 1 0 ... .... .. , ... ...,.

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closure. This induces repose, according to Simonds (1983) , and is defensible territory, according to Condon (1988) . The garden is functional as well in that it provides windbreaks , shade in summer, solutions to drainage problems , and low rraintenance benefits. ADJACENI' AGRICULTURAL LAND DESIGN Agricultural design is explored in figure 35 in a way that maximizes bird habitat on adjacent agricultural lands, respects the functional visual quality of farms in the urban fringe, and could be economically feasible for the farrrers. The particular farm that is designed will soon becane the gravel processing plant site for the Branley Lakes project, and then be reclaimed for agricultural uses. The topography in this area does not require the use of contour plowing to reduce soil erosion into the South Platte River. Wind erosion is a therefore dense varied shelterbelts are necessary. Shelterbelts also play an important role in visually blending diverse uses together. Strip cropping is used because alternating strips of corn with soybeans , for example , will result in the addition of nitrogen in the portions planted with a legume , ultimately benefitting the soil more than planting a monoculture of corn, as is the current general practice. Birds also benefit from the contact point between two crop types. Spring plowing significantly increases the availability of food at a critical time. By not plowing in the fall, grain missed during harvest provides a fall and winter food source, and the stubble is habitat for mice and other hawk and owl prey (O' Connor 1986). By spring, food supply is short. Plowing flushes invertebrates from the soil at a time when seed sources are at their lowest, providing additional food at a critical time. Thus, farmers in the project area vicinity should not plow until spring. llA

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ADJACENT FMM

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VEl'ERAN 'S PARK/SMITH NATURAL AREA Two scales of design are presented; the first encompasses the core park, the natural area, and the connections to the South Platte River/gravel lake corridor. The core park is then designed in more detail at a finer scale. PARK SCALE Figure 36 shows the overall design for the Veteran' s Park/ Smith Natural Area. Since there would be little similarity between the existing Veteran's Park and the prop::>sed park, it is prop::>sed that the name be changed to Brighton Bird Habitat Park, or something similar. The emphasis of the design is on providing bird habitat and bringing people into concentrated contact with birds in different habitat types, from typical suburban gardens, to agricultural fields, to grasslands, to forest, to wetlands, to lakes. The site is divided into several zones . The core park (described in more detail in the next section) is where people park their cars, picnic, read interpretive signs that tie into landscape ecological concepts, visit an interpretive center, and observe suburban, agricultural, and demonstration gardens. From this intense core, two loop trails and the South Platte River trail access other park areas. The eastern loop trail (l/ 2-mile) follows a shelter belt to the Smith Natural Area . A weir has been placed on the McCann Ditch to dam water and flood about l acre currently daninate d by weedy species. By grading the area to be flooded to varying depths (ranging from 6-inches to 3-feet deep), a rich, diverse area of emergent and submergent plants will occur for warbler and yellowthroat habitat, as well as for educational and aesthetic pleasure. Islands are created and the trail becomes a series of l?n

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r'OI'O'!>< TI"<"''L-.crx,e ,.,_. TO w e ; V"oNC> P"tNO """"'-I"CU:::o T Figure 36 '"""'-l"\alDD,.. a
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boardwalks connecting uplands arrl wetlands. A loop then brings visitors to the South Platte River bank where prime kingfisher habitat is provided. Flooding this 1-acre site may additionally recharge the water table and allow cottonwoods and other shrubs to grow along the presentl y bare riverbanks, on top of which sidewalk pieces and fill dirt have been dumped. Sane nature groups have experimented with counteracting the stranding effect of river channelization by excavating 8-inch diameter holes until groundwater is reached, then inserting cottonwood poles. The cottonwoods root and sprout, eventually suckering to replenish t h e stranded, decadent riparian forest (Cooper , pers. comm. 1988). Crossing the South Platte River via a footbridge, visitors access the property across the river, which is notable for its open cottonwood forest. Grazing will no longer take place on this property, so shrubs may becane reestablished to provide more vegetation layers. Supplenental shrub and tree planting will also occur i n areas shown in figure 36. The trail first accesses the riverbank where wintering waterfowl, kingfishers, hawks , and other birds can be observed. Following a shel terbel t to the west, visitors reach a tangle of trees and shrubs that grow at a pond intersection on the adjacent farm . The canopied trail then wanders through the open f orest where owls and hawks frequently perch. Crossing the footbridge again, the South Platte River trail leads to the south, where visitors enter the gravel lake environment. A short 1-mile trail loops around the first lake so that visitors can observe waterfowl, shorebirds , and wading birds, such as herons . CORE PARK SCALE This site was selected as the heart of the park because of its proximity to a diversity of land, water, and plant forms , and because it is easily 122

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a ccessible and protected from 100-year floods by b eing raised 4-to-5 feet . Visitors park in a curvalinear parking are a for 25 cars and two buse s and then pass through a transition garden where landscaping techniques for attracting birds to suburban gardens are demonstrate d (figure 37) . A seri e s of camnunity education buildings, incrementally built (that can be conside r e d as building patche s connecte d b y corridor walkways) , can serve as a museum , auditorium, canmunity meeting room , classroom, and/or administrative office . The building and surrounding landscape design i s sensitive to wind directions, solar access, local materials, and v i ews. It may be noted that building entrance plantings are massed so that they incorporate the most agreeable shape chose n in chapter three by all people informally sampled. Surrounding the building are gardens. To the east, the Mccann Ditch has been extended toward the building to form a shallow wetland, across which people can cross to r each the loop trail. Sitting areas and other amenitie s are provided. To the north, agricultural display gardens, perhaps sponsored by the Adams County Soil Cons ervation District, address diffe r ent techniques f o r providing bird habitat on farms through crop patterning and shelterbelt plantings. Woven through the connecting walkwa y s between buildings are suburban d emons tration gardens that s how how to attract hilllliT\ingbirds , seedeaters, woodpeckers, and other birds. To the w est i s a large native grass rreadow for children' s play, and on the rim, the picnic area take s advantage of proximity and v i e ws toward the river . Figure 37 diagrams the use of landscape ecological concepts to create this are a f o r people's enjoyrrent and for bird habitat. This nature/community center does not s eparate itself from its human i zed s etting, as many local nature centers do. It does not foster mus e um-piece pre servation, although as gravel mining developnent continues, it may becorre 12 3

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one of the last unmined , un-industrialized patches in the Denve r netropolitan area along the South Platte River. The core park rerrains tied to its suburban and agricultural settings b y exhibiting and interpreting the interrelationships between birds and these settings and the relationships betwe e n these settings. Visitors touring the gardens may like the idea of a ttractin g birds and plant similar gardens, reducing the contrast between the display gardens and the surrounding homes and fields. SUMMARY Lan dscape ecological c oncepts can and should be app lied at the small-scale design level to create continuity between concepts and d esign. The idea of designing for spatial variety to attract b i r d s and to create pleasurable , interesting gardens for people is most neaningful on the small scale . Rather than quote research and theories, one can see that it is pleasurable , once theorie s are applied to a back yard or nature/ ccmnunit y center. And designing to support habitat over long period s of time results in a more naturalistic, realistic planting schene, rather than planting an even-aged suburban forest. Although landscape ecologists tend to focus on the larger landscape scal e , designers can c ontribute significantly to the field by carrying concepts to the d esign detail scale and creating place s that make people awar e of the structure, functions, and dynamic qualitie s of a place .

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CHAPI'ER SIX: DESIGN IMPLICATIONS AT THE RffiiONAL SCALE INI'RODUCI'ION Thus far, each chapter's design has telescoped down in scale to show the continuity between goals and methodology. What are the implications of these srraller scale designs to the regional scale, the scale at which this study began? How does this bird habitat and passive recreation area affect the regional scale? This chapter briefly looks at what would be accomplished on a larger scale by this design and what could be accomplished if other regional habitat protection strategies W2re also undertaken. RffiiONAL ACcx::MPLISHMENI'S OF THIS DESIGN Denver metropolitan area landscat:es are illustrated in chapter 2 , figure 2. From this aerial photo, it is easy to see the few remaining, isolated "natural" patches. With the addition of the study area as another green patch, three important connections on a regional scale have been made. First, a 1000-acre habitable stopping and resting place has been provided on the important South Platte River migratory corrir'l, ...... After South Platte Park, 40 miles to the south, this is the largest resting place along the river for birds flying north. Besides the river itself, various patches of forest, shrubs, W2tlands, and lakes provide a variety of habitat tYtBS for different birds following the river corridor. In addition, the site contains a natural and designed mixture of gaps and different vegetation ages so that developmental stage s can perpetually provide habitat. Second, the study area is connected via the Third Creek vegetated trai 1 to the east to Barr Lake, which for this century has developed into the most important bird habitat area in the northern Denver metropolitan area. 1 ?h

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By connecting the two areas with vegetated corridors, a clustered effect results, which reduces the isolation of roth areas. Creating wid e shelterbelts between farms, protecting vegetation along stream and ditch corridors, and not intensivel y developing adjacent uplands helps create a regional approach to preservation without prohibiting economic development of a considerable land area (Noss 1983). Third, interpretation of landscape ecological conc epts is a critical canponent of the design's efficacy. Peopl e are encouraged in an aesthetically pleasing way to learn ai:x:>ut regional and local habitat protection. They can learn ai:x:>ut the econanic, aesthetic, and ethical benefits derived from participating in forming the land to preserve heterogeneity and interconnections. They can feel the pleasure of greater awareness of the large picture and feel a part of it. Landscape ecology's vocabulary can be an effective interpretive tool since concepts of patches, corridors, etc. are easy to visualize and understand, especially i f aerial photos are used to explain concepts on larger scales. Interpretation is not oriented toward slap-on-the wrist messages , as is common in many natural area interpretive programs. Landscape ecology emphasizes the study of structure, function, and change in a human-dominated world, and fosters an interdisciplinary work-together-for-a-common-good attitude more effectively than an attone -for-your-sins approach. Interpretive messages and demonstration landscape designs can set an example that may be repeated b y individual homeowners , developers, and farmers throughout the Denver metropolitan area. If so, this site could have a much larger, though more dispersed, regional impact than any single vegetated corridor could have. Highways and phone lines become the transmission corridors of this idea, perhaps resulting in landscat:es which can affect people far beyond the Brighton area. 127

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POI'ENI'IAL RffiiONAL ACCXMPLISHMENI'S OF THIS DESIGN The site offers an important, connected habitat area, but is not the missing link in the regional habitat protection picture. Many other connections need to be made to avoid imninent further fragrrentation of green space for people and wildlife. The site could fit into two different scenarios. First, the South Platte River is extremely important as migratory and resident bird habitat and as a recreation route for humans. Preservation efforts could concentrate on the river and its tributaries. Efforts have been taken to provide a connected trail system and pocket parks along the river, kno.vn as the Greenway (Spirn 1986) . Using landscape ecological concepts, proponents of the Greenway would create patches of different shapes, sizes, and vegetation age classes along the river (figure 38) . They would protect adjacent uplands and create wide corridors. Creating connections along stream tributaries that connect to the rrountain front, another imrortant bird migratory route, would be enphasized. They would reclaim existing sterile gravel pits, some for recreation, same for habitat protection, using concepts of sculpted edges, perpendicular patch shapes, and peninsulas to attract wildlife. Surface runoff would be treated before discharging it into the river and more stringent arrmonia and nitrate controls would be placed on sewage treatment plants to reduce pollutants discharged i nto the river. These solution s would be vital to improving Denver's environment, but would be expensive, since corridor real estate is very costly to purchase and since economic development is slow at present. The second scenario emphasizes preserving remaining open agricultural and open sr:ace lands that may be under development pressure as a result of new highway and airport construction. The 470 highway plan calls for a ring of highways encircling the Denver metropolitan area since the South Platte 128

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/ . . . . . I j "".. . LANDSCAPES REVISITEP SCENARIO A . "'

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River/Interstate-25 highway corridor is already developed and congested. The new highway ring, coupled with potential new airport construction northeast of Denver, would create developnent focus further away fran the urban core. Rerraining important habitat tracts must be identified for preservation imrediately and connected to other protected areas if further habitat isolation is to be avoided. This scenario is shewn in figure 39 . For example, the proposed E 470 highway may be aligned on top of Third Creek tetween Branley Lakes and Barr Lake. Third Creek 'WOUld be channelized into a culvert for a distance of over l mile, breaking the very important link tetween the two protected areas. If counties prepare natural areas plans (eg. Boulder County Parks and Recreation 1987) and place high priority on vital habitat corridors, plans like culverting Third Creek may not be realized. SUMMARY The site design presented in this thesis not only has positive implications for the study area, but also on a regional scale. If supplerrented by large scale planning efforts by Denver metropolitan counties and cities, the impact of this area 'WOUld be magnified as it became part of an interconnected system of habitat for wildlife and recreational opportunities people. Two scenarios VJere presented: one that shOVJed the site as an important link in a linear corridor protection plan for existing developed areas, and one that demonstrated a natural area plan in light of future ring developnent in the Denver metropolitan area. nn

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. .. LANDSCAPES REVISITED SCENARIO 8

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CHAPI'ER SEVEN: CON:LUSION EVALUATI!'K; THE USE OF LANDSCAPE ECOr..cx:;ICAL CONCEPTS IN BIRD HABITAT DESIGN INI'RODUcriON This thesis wasundertaken with the assumption that landscape ecology would be an appropriate tool for bird habitat design along the changing South Platte River. The conclusion is that it is effective because, as indicated in the summaries of the preceeding three chapters, established objectives hav e been met at each level of design. The questions arise : How was it effective? What other comparable approaches could have been taken in this thesis? What further research could follow from this thesis? And finally, in general, what are the ramifications of using a landscape ecological approach to design? EFFICACY OF LANDSCAPE ECOr..cx:;ICAL MEI'HOOOI..CGY Landscape ecology served both as an evaluative and form -generating design tool in this paper. As an evaluative tool, it surpasses typical two-dimensional site analyses of soil, vegetation, and wildlife layers by intertwining these components into structural elements that form the basis for species' orientation in space: patches, corridors, and matrices. FUnctions of repeated structural patterns were analyzed to understand if a particular patch attracted animals, if corridors served as barriers or conduits for species movement, and haw the matrix influenced the site by introducing exotic species, for exarrple . The dynamic qualities of the site were also examined in terms of the effect of river channelization, cottonwood regeneration, and socio-cultural changes, such as gravel mining . This synthetic type of analysis was applied to understand the study area, as well as to understand the interactions between the study area and adjacent 132

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farms and suburbs, so that places have not been studied apart from their surroundings. This evaluative approach served as a design net; a reminder that understanding the site is set in time and space and is rrore than just a canpendium of resource data. As a form-generator, three concepts were repeated at each design scale that strongly influenced the design of forms . Site spatial heterogeneity was advocated for its positive effects on this area's bird species by providing a greater variety of habitat niches. A variety of horizontal and vertical proximities and patch shapes were formed to create high species diversity, according to research cited. The concept of spatial heterogeneity also was used to create positive responses in human site users since it induces rroverrent, surprise, and interest. In application to humans, however, sorre sources (Condon 1988) warned that too much diversity fragments a space; volurretric spaces must also be formed. The gravel lake matrix unified the space and fragmentation was avoided. By considering temporal heterogeneity in a design, the designer was encouraged to do two things: create desired patch shapes and corridors that would perpetuate spatial heterogeneity over time through plantings; and allow disturbance regimes to continue so that processes would be more selfregulating rather than designed. This first approach is risky in that plans may be forgotten over time without careful long-term commitrrent. The second approach is difficult in human-dominated areas since disturbances such as flooding and fires are not compatible with adjacent land uses. Clearly research is needed to derive publically acceptible and biologically sound methods of perpetuating disturbance regimes (Johnson 1986). The third concept of creating interconnections between regionally important habitat and recreational areas is critical as urban areas continue to enlar g e , stranding more and more prime bird habitat and recreational areas. Cr eating 1 -:)-:)

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c onnections within the site was also important so that providin g nesting habitat and recreation not in conflict. Using these three conc epts allows for K o h 's "ecological and e volutionary fit" between developiTEnts such as grave l mi ning and subdivisions and migrating and resident birds. Although the d esign approach was thorough and effective , it did not generate remarkably new design processes or f orms , and in fact, was rather eclectic, e specially as design tel e scoped down in scal e . In order to fulfil l the purpose of designing for human enjoYITEnt , design references had to be wove n into the cloth of this thesis. Landscape ecologists have expressed interest in incorporating more socio-cultural research into the understanding o f landscape-scale patterns and feel the field will move in that direction (Galley pers. corrrn. 1988). When it does , landscape ecological r:erspective s will becane even more applicable to design than they already are. Par:ers such as this one , especially if the designs are actually built, can h elp the field move in that direction. OI'HER D ES IGN APPROACHES AND FUI'URE RFSFARCH NEEDS The qualitative ITEthod use d in applying s electe d landscape ecological conc epts to this rapidly and significantly changing bird migration corridor was in this c a s e appropriate. Ideally , a research project should be established at this site to t est the sr:ecific application of Schoener's perpendicular patch research in the semi-arid west, or whether or not peninsulas conc entrate animal activity in suburban areas as they d o in scientists' research plots . Results from such tests would serve to expand the application of landscape ecological concepts to d esign in human dominat e d s ettings. The application of a geographic information s yste m to to identify large -scale landscape structure and predict impacts o f c ha n g e 134

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on this structure would also have been appropriate to evaluate the site and its context, but was beyond the scope of this thesis. A more rnatherratical approach could also have been taken using habitat suitability indices (U.S. Fish and Wildlife Service 1981) to indicate precisely how much habitat for individual species is created (Burley pers. camm. 1988) and designing according to optimal numbers. Out of deference to Albert Einstein, this technique was not pursued further: "When mathematical propositions refer to reality they are not certain; when they are certain, they do not refer to reality" (Condon 1988). 'Ib evaluate which approach, qualitative or quantitative, would be more effective, a comparative research study is needed. Another comparative study of interest would be to strictly apply Christopher Alexander's Language (1977) to this landscape ecological design. As the comparative landscape structural analysis chart (Table 4) in chapter three Alexander' s ideas are closely aligned with landscape ecologists' ideas of spatial, long-term understanding across scales. However , since Alexander tends to focus primarily on people in towns , the language may not be adequate for this design that involves birds in a h ybrid site. The author of this thesis proposes that a new pattern language for heterogenous urban/"natural" areas could be created by combining aspects from both Alexander's and landscape ecologists' spatially oriented empirical research. In this new language , Alexander 's focus on human comfort, meaning, and "sense of place, " which is lacking in landscape ecological concepts and must be drawn from design and other references at present, could be enhanced by designing for the well-being of other species. More references are needed which advocate designing for humans and other species that affect and are affected by the landscape. 135

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OVERALL RELATIONSHIP BEIWEEN lANDSCAPE EX:OLCX;Y AND DESIGN A landscape ecological approach is more difficult than a traditional design process of site canponent analysis, program developnent, and design. A holistic approach, where biological, physical, and cultural interests are considered at a variety of scales over time, is a strenuous undertaking, but it is a more ethical approach. According to Forman (1987): "Simpl y stated, in land use d ecisions and actions it is unethical to evaluate an area in isolation from its surroundings or from its dev e loprrent over time. Ethics impel us to consider an area in its broadest spatial and temporal perspectives .... It is unethical to think a boundary is impenetrable and an action can be isolated" (p.220). Thus, even though more difficult, it is necessary to undertake the holistic task, which seems to be appealing to an increasingly large audience of designers (Koh 1982, Lyle 1985 , Howett 1987, Condon 1988 and others) and scientists (Forman 1987 and others) alike. As this approach continues to develop with the involvement of many disciplines, designers may move away from considering only short-term human needs, of which many designers are accused (Berger 1987) ; and ecology may continue to broaden further beyond the study of single species in pristine settings. The expansion of and intermingling between both design and ecology is occurring through landscape ecology. Whe n in 1966 , the originator of the term landscape ecology, Carl Troll, was asked about the discipline, h e replied: "It is not really sanething new. It is just an attitude , an approach, a state of mind" (Zonneveld 1982 p . 15). Therefore, Zonneveld concludes, an yone--from geographer to landscape architect--"who has the attitude to approach our environrrent ... as a coherent 136

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system, as a kind of whole that cannot be really understood from components only, is a landsca:pe ecologist" ( p . 15) . Therefore, in this thesis, although a landsca:pe ecological approach did not result in previously undiscovered design forms or processes, it resulted in a displacement of a reductionist approach in favor of a holistic approach, which ultimately fosters a humane environmental ethic. 137

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Axell, H . and E . Hosking . 1977 . Minsmere : Portrait Bird Reserve . London : Hutchinson and Co. 254pp . Banks , R . C. 1976 . Reflective plate glass--a hazard to migrating birds. BioScience 26(6):414 . Barr Lake State Park. n.d. Bird List. Brady, W., D . R. Patton, and J . Paxson . 1985 . The development o f southwestern riparian gallery forests. Paper presented at the Riparian Ecosystems and Their Management : Reconciling Conflicting Uses Conference . Tucson, AZ, April 16-18 . Pp . 39-43 . Brawn, M . and J . D . Dinsmore . 1986 . isolation for marsh management . Implications of marsh size and Journal Wildl. Manage . 50:392-397. Bull, J . 1974. Birds of New York State. Garden City, NY: Doubleday / Nat . Hist. Press. 655pp. catchpole, c. K. 1975 . Gravel pits as new wetland habitats for the conservation of breeding bird communities. Applied Science Biological Conservation 8 : 47-59 . Chronic, H . 1980 . Roadside Geology of Colorado. Missoula, MT: Mountain Press Pub. Co. 322pp . Colorado Nongame Advisory Council of the Colorado Division of Wildlife , sponsors. 1985 . Colorado wildlife workshop: species of special concern. 92pp. Condon , P . M. 1988 . architecture. Cubist vol urretric and landscape Landscape Journal. 6(3): 1-38 . DeBoer , s . R . 1965 . "Bob Speer's Challenge to Denver." Errpire Magazin e , Nov. 21, pp. 6-9. DeGraaf, R . M . 1975. PhD dissertation. Suburban habitat associations of birds. 214pp . Denve r Regional Council of Governments . 1987 . Amherst, MA: EDAW. 1974 . San Francisco Bay National Wildlife R efuge Master Plan. Prepared for the U . s. Fish and Wildlife Service . San Francisco, CA. 47pp . Forman, R . T . T . 1983. An ecology of the landscape. BioScience 3 3 ( 9) : 535 . ---, 1986 . Eirerging directions in landscape ecology and applications in natural resource management . In: R. Herrmann and T. Bostedt-craig ( eds. ) , Proceedings of the Confere nc e on Science in the National Parks. Fort Collins, CO: CO State Uni v., July 13-18 . 1 3 8

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, 198 7 . Fran plant ccmnunities to landscapes in conservation --""7" inventories: a look at the Nature Conservancy (USA) . Biol . Conserv. 41: 11-37 . Prose, B. L. 1985 . Habitat suitability index models: belted kingfisher. u.s. Fish and Wildl. Serv. Biol. Rep . 82(10 . 87) . 22pp . Romme, w . H. 1987 . Landscape ecology. Ecology 68(1): 233-234. Roth , R . R . 1976 . Spa tial heterogeneity and bird species diversity. Ecology 57(1): 773-782 . Ryszkowski , L . and A . Kedziora. 1987 . Impact of agricultural landscape structure on e nergy flow and water cycling. Landscape Ecology 1(2) :85-94. Sampson, J . J . and T . G. Barber. 1 974 . Soil survey o f A dams County, CO. U. S. Dept . of Agri c . , Soi 1 Conserv . Serv . in coop. with CO agr ic . Exper . Sta. U . S . GPO. 235pp . Schmidt, T . and Assoc . 1981 . Shaker Lakes Nature Center: A report on trail development design guidelines. Cleveland, OH. 12pp . S c hoener, T . W . 1971. Theory of feeding strategies. Ann . Rev . Ecol. S ystematics 2 : 369-404 . Schroeder, R. L . 1982 . Habitat suitability index mcrlels : yellow warbler. U . S . Dept. Int., Fish Wildl. Serv. FWS/OBS-82/ 10 .27. 7pp. ---. 1986 . Habitat suitability index models :wildlife species richness in shelterbelts. u . S . Fish Wildl. Serv. Biol. Rep . 82(10 .128). 17pp . Short, H . L . 1983 . Wildlife Guilds in Arizona Desert Habitats. U . S. Dept . of Interior, Bureau of Land ManagEment Technical Note 362 . Fort Collins, CO. 258pp . --.,1984 . Habitat suitability index models : Western grebe. u. S . Fish Wildl. Serv. FWS/ O B S-82 / 10 .69. 20pp . ___ and R . J . Cooper . 1985 . Habitat suitability index models : great blue heron. U . S . Fish Wildl. Serv. Biol. Rep. 82(10 .99). 23pp . S imonds , J . Design. 0 . 1983 . Landscape Architecture : Manual of Site Planning and New York: McGraw Hill. 33lpp. Soul e , M . 1986 . Conservation biology. BioScience 36(12) : 811-816 . Sousa , P . J. 1982. Habitat sui tabi li t y index mcrlel s : Lewis ' woodpecker. U . S . Dept . Int., Fish Wildl. Serv. FWS/OBS-82/ 10 .32. 1 4pp. Spirn, A . 1986 . The Granite Garden : Urban Nature and Human Design. N e w York: Basic Books:-314pp. 1 4 1

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Sprunt, A . 1975. Habitat management implications of migration. Pape r presented at the Symposium for Management of Forest and Rang e Habitat for Non-game Birds, Tucson , AZ. pp. 82-86 . Steiner, F., K. Brooks , and K. Struckrneyer . 1981. Determining the r egional context for landscape planning. In Regional Landscape Planning: Proceedings of Three Educational Seminars. Washington , D . C . : Annual Meeting of the American Soc. of Landscape Architects. ___ , and J . E . Theilacke r , ed. Protecting Farmlands . Westport, cr: AVI Pub. Co. , Inc. 312pp . Steinitz, C . 1988. When visual quality and ecological integrity are mutually supportive or in conflict (and what to do al::x:::mt it): a case study based upon (still-in-progress) research in Acadia National Park. Paper presented at the Third Annual Landscape Ecology Symposium , Albuquerqu e , NM Stokes, D . w . 1979 . Guide to the Behavior of Common Birds. Boston: Little , Brown, and Co. 22lpp. Swanson , G. A . 1987. Developing a bird garden. Birder' s World 11(1):38-43. Tuttle Applegate Rindahl , Inc. 198 7a . Application for zcn e change : mineral conservatio n , Bramley Lakes , Brighton, CO --:--:-. l987b . Draft Planned Unit Regulations for West Bramley Lak es, Brighton CO. 23pp . , Forest Service. I Narratives. 1981. Wildlife and fish habitat relationships, Prepared b y USDA Rang e and Wildl. Manage . 4llpp . United State s Department o f Interior Fish and Wildlife Service. 1979. An annotated bibliography on planning and management for urban-suburban wildlife. Biol. Serv. Program FWS/OBS-79/25. 256pp . ___ . 1981 . Standards for the developnent of habitat suitability inde x models . u . s . Fish and Wildl. Serv. Bull. Division of Ecol. Serv. , n .p. Urban Drainage and Flood Control District. 1984 . South Platte Ri ve r : Major Drainage way Planning, Chatfield Dam to Baseline Road , Phas e s A and B . Submitte d by Wright Water Engin eers, Inc. V o s , D . K . 1984 . Humans and herons. Colorado Outdoors 11(3) : 12-16 . Well er, M. w. 1981 . Freshwate r Marsh es: Ecology and Wildlife Managemen t . Minn eapolis: Univ . o f MN Press. l46pp . , n .d. Waterfowl management technique s for wetland e nhancemen t , --r estoration, and creation useful in mitigation procedures. Draft manuscript. Wiens, J . A. 1969. An appr oach to the study of ecological relationship s among grass land birds . Orni thol. Monog. 8 : l -9 3 . 142

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. 1973. Pattern and process in grassland bird communities. Ecol. ---Monog. 43:237-270 . ---. 1974. Habitat heterogeneity and avian community structure in North Arrerican grasslands. Am. Midl. Nat. 43:237-270. Wright Water Engineers, Inc. 1985. Draft Adams County Gravel Mining Criteria. Denver. Unpublished. Yahner, R. H. 1983. Seasonal dynamics, habitat relationships, and management of avifauna in farmstead shelterbelts. Journal Wildl. Manage. 47(1):64-77. Zonneveld, I. e. S. 1981. Land(scape) ecology, a science or state of mind? In s. P. Tjallingii and A. A. de Veer, eds. Perspectives in Landscape Ecology, Proceedings of the International Congress organized by the Netherlands Society for Landscape Ecology. Veldhove, the Netherlands: April 6-11, 1981. 143

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1. J. 2. v. 3 . c. 4 . D. 5. M . 6 . R. 7. R . 8 . F . 9 . c. 10. B. 11. D. 12. J . 13. E . 14. D . 15. E. 16. J . 17. G . 18. G. 19. J . 20. J . PERSONAL CCM-ruNICATION Burley, Landscape Architect, CO State University, February 1988 Baffe, Engineer, Adams County Soil Conservation District, February, 1988 Chase , Ornithologist, September, 1987 Cooper, Wetlands Ecologist, March , 1988 Figgs, Ornithologist, September, 1987 Forman, Ecologist, Harvard University, March 1987 French, Aquatic Ecologist, Metropolitan Denver Sewage District, April, 1988 Golley, Ecologist, University of Georgia, March 1988 Gray, Landscape Architect, Adams County, November, 1987 Hernbrod, Recreation Specialist, CO Division of Wildlife, March 1988 Jewell, Biologist, CO Division of Wildlife, December 1987 Koh, Landscape Architect, Texas Tech University, September, 1987 Longh urst, City Forester, City of Brighton, CO, March 1988 Macintosh , Farmer, November 1987 Moore , Director of Community Development , City of Brighton, CO, November , 1987 Sayre, Planning Consultant, City of Brighton, CO, April 1988 Swanson, Minneapolis, MN, December , 1987 Tuttle, Engineer, Tuttle Applegate Rindahl, Inc. March, 1988 Wiens, Ecologist, CO State University, November, 1987 Woodling, Fish Biologist, CO Division of Wildlife, March , 1988 144

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APPENDIX TARGEI'ED SPECIES AND THEIR GUILDS The following species have been aggregated because their feeding and /or breeding requirerrents are similar to the targeted species ' requirerrents. The assumptions is being made that if prirre habitat is provided for targeted species, the following species may also be present. Great Blue Heron SnONy Egret Double-crested Cormorant Black-crowned Night Heron Yellow-crowned Night Heron White-faced Ibis Sandhill Crane Blue-winged Teal Green-winged Teal Cinnamon Teal Pintail Oldsquaw Gadwall Mallard Northern Shoveler Arrerican Coot Sandpipers, plovers, phalaropes Arrerican White Pelican Osprey Bald Eagle Hawks Long-eared and Great-horned Owls Kestrel M3.gpie Craw Kingfisher Pintail Oldsquaw Terns and gulls Swallows Sandpipers, plovers, phalaropes, dowitchers Kestrel Godwit Flycatchers 145

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Western Grebe Pied-billed, Eared, and Horned Grebes Widgeon Teals Osprey Mergansers Canmon I.oon Goldeneyes Ruddy Duck Ring-necked Duck Redhead Sea ups Coot canvasba.ck Bufflehead Lewis ' Wocxipecker Red-headed Woodpecker Downy Woodpecker Hairy Wocxipecker Northern Flicker Hawks Prairie Falcon Eastern Screech O.Vl Kestrel Violet-green Swallow Tree SWallow Starling Ma.gpie Say ' s Phoebe Western Wood Pewee Nuthatches Western Kingbird Black-headed Grosbeak Bro.vn Creeper Mountain Bluebird Yellow Warbler Yellow-breasted Chat Other Warblers Gray catbird Rufous-sided Towhee Whi t e -crawned Sparrow Whit e -throated Sparrow Tree Sparrow Song Sparrow Lincoln's Sparrow Lazuli Bunting Orioles Ring-necked Pheasant Mockingbird Eastern Kingbird Broad-tailed Hummingbird Flycatchers 146

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Wocrl Duck Yellow-billed Cuckoo Redstart Brown-headed Cowbird Common Yellowthroat Sedge Wren Marsh Wre n Marsh Hawk Willet Northern Water Thrush Savannah Sparrow Harris ' Sparrow Snipe Virginia Rail Sora Water Pipit Brawn-headed Cowbird Yellow-headed Blackbird Red-winged Blackbird Brewer ' s Blackbird American Least Bittern 147