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Creating a rapid ecological assessment for anthropogenic impacts

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Title:
Creating a rapid ecological assessment for anthropogenic impacts an examination of the High Line Canal Trail
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Hays, Rebecca Marie ( author )
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Denver, CO
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University of Colorado Denver
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English
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Pollution -- Environmental aspects ( lcsh )
Nature -- Effect of human beings on ( lcsh )
High Line Canal (Colo.) ( lcsh )
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bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

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Similar to other urban areas around the United States, Denver, CO provides many outdoor trail opportunities that interact with the urban landscape. The High Line Canal Trail is one such trail example that goes through a Wildland-Urban Interface (WUI). This study evaluates the High Line Canal Trail using the straight-forward technique of a Rapid Ecological Assessment (REA) to understand the anthropogenic impacts along a multi-use trail. This study surveyed ten, one-kilometer segments spaced out in ten kilometer increments for the duration of the High Line Canal Trail (total length approximately 66 miles/106 km). This allows for a random sampling of the trail, while maintaining time and budget constraints. Testing of the study area was conducted between August and October, 2013 to ensure full vegetation growth with little weather interference. Several parameters were examined using REA: soil disruption, disturbed vegetation, bare ground, and vegetation density, including the relationship of these parameters with property values along the trail. Additionally, a paired t-test was used to evaluate any significance between the canal and non-canal side of the trail of each parameter. These parameters revealed overall anthropogenic disturbance along the High Line Canal Trail, particularly with the vegetation disturbance parameter, though little correlation between any type of disturbance and regarding property values was found. Similarly, no significance was found between the canal and non-canal side of the trail. This study, however, provides an important basis for assessing urban trail interactions with an eye towards comprehensive management in WUI areas. It is easy to replicate and can be the basis for assessments along any urban trail
Thesis:
Thesis (M.S.)--University of Colorado Denver. Environmental sciences
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Includes bibliographic references.
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System requirements: Adobe Reader.
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Department of Geography and Environmental Sciences
Statement of Responsibility:
by Rebecca Marie Hays.

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University of Colorado Denver
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Full Text
CREATING A RAPID ECOLOGICAL ASSESSMENT FOR ANTHROPOGENIC
IMPACTS: AN EXAMINATION OF THE HIGH LINE CANAL TRAIL
By
REBECCA MARIE HAYS
B.A., The George Washington University, 2010
A thesis submitted to the
Faculty of the Graduate School of the
University of Colorado in partial fulfillment
Of the requirements for the degree of
Masters of Science
Environmental Sciences
2014


This thesis for the Masters of Science degree by
Rebecca Marie Hays
has been approved for the
Environmental Sciences Program
by
Casey Allen, Chair
Gregory Simon
Jon Barbour


Hays, Rebecca Marie (Master, Environmental Sciences)
Creating a Rapid Ecological Assessment for Anthropogenic Impacts: An Examination of
the High Line Canal Trail
Thesis directed by Assistant Professor Casey Allen.
ABSTRACT
Similar to other urban areas around the United States, Denver, CO provides many
outdoor trail opportunities that interact with the urban landscape. The High Line Canal
Trail is one such trail example that goes through a Wildland-Urban Interface (WUI). This
study evaluates the High Line Canal Trail using the straight-forward technique of a Rapid
Ecological Assessment (REA) to understand the anthropogenic impacts along a multi-use
trail. This study surveyed ten, one-kilometer segments spaced out in ten kilometer
increments for the duration of the High Line Canal Trail (total length approximately 66
miles/106 km). This allows for a random sampling of the trail, while maintaining time
and budget constraints. Testing of the study area was conducted between August and
October, 2013 to ensure full vegetation growth with little weather interference. Several
parameters were examined using REA: soil disruption, disturbed vegetation, bare ground,
and vegetation density, including the relationship of these parameters with property
values along the trail. Additionally, a paired t-test was used to evaluate any significance
between the canal and non-canal side of the trail of each parameter. These parameters
revealed overall anthropogenic disturbance along the High Line Canal Trail, particularly
with the vegetation disturbance parameter, though little correlation between any type
of disturbance and regarding property values was found. Similarly, no significance
was found between the canal and non-canal side of the trail. This study, however,
m


provides an important basis for assessing urban trail interactions with an eye towards
comprehensive management in WUI areas. It is easy to replicate and can be the basis for
assessments along any urban trail.
The form and content of this abstract are approved. I recommend its publication.
Approved: Casey Allen


DEDICATION
I dedicate this work to my loving family for always believing I can succeed.
v


ACKNOWLEDGMENTS
I would like to thank Dr. Casey Allen for being an excellent advisor! This thesis would
never have come together without him. I would also like to give special
acknowledgement to Jordan Cohen and Hannah Edmond for being amazing field
assistants!
vi


TABLE OF CONTENTS
Chapter
1. Introduction.........................................................................1
1.1 Rapid Ecological Assessment.......................................................2
1.2. Wildland-Urban Interface.........................................................2
1.3 Home Values.......................................................................5
1.4 Subsequent Chapters...............................................................5
2. Introduction to Methods..............................................................7
2.1 Study Site........................................................................8
2.2 Data Gathering..................................................................10
2.3 Parameters......................................................................14
2.4 Testing.........................................................................16
3. Analysis of Results.................................................................18
3.1 Number of Transects at each Site Location........................................19
3.1.1 Disturbed Soil...............................................................21
3.1.2 Disturbed Vegetation.........................................................22
3.1.3 Bare Ground..................................................................24
3.1.4 Vegetation Density...........................................................25
3.2 Statistical Testing..............................................................26
3.3 Site Locations...................................................................26
3.3.1 Site 1.......................................................................27
3.3.2 Site 2.......................................................................28
3.3.3 Site 3.......................................................................29
3.3.4 Site 4.......................................................................30
3.3.5 Site 5.......................................................................31
3.3.6 Site 6.......................................................................32
3.3.7 Site 7.......................................................................33
3.3.8 Site 8.......................................................................34
3.3.9 Site 9.......................................................................35
3.3.10 Site 10....................................................................36
3.4 Home Values......................................................................37
4. Discussion and Recommendations......................................................38
vii


4.1 Discussion of Analysis.........................................................38
4.1.1 Parameters.................................................................39
4.1.2 Statistical Testing........................................................41
4.1.3 Home Values................................................................42
4.2 Societal Applications..........................................................42
4.3 Future Work and Recommendations................................................44
Appendix
A. Site Worksheet....................................................................51
B. In-the field Worksheet Example..................................................52
References............................................................................46
viii


LIST OF TABLES
Table
2.1. Location of the study areas along the High Line Canal Trail................9
2.2. Approximation of how each parameter is measured............................11
2.3. Visual representation of indicator values..................................12
2.4. Matrix of each parameter...................................................15
IX


LIST OF FIGURES
Figure
2.1: A map showing all 71 miles of the High Line Canal Trail............................7
2.2. Distances measured at the High Line Canal Trails edge...........................11
3.1. Average indicator values at each site for Disturbed Soil..........................21
3.2. Average indicator values at each site for Disturbed Vegetation....................22
3.3. Average indicator values at each site for Bare Ground............................23
3.4. Average indicator values at each site for Vegetation Density.....................25
3.5. Site 1...........................................................................27
3.6. Site 2...........................................................................28
3.7. Site 3...........................................................................29
3.8. Site 4...........................................................................30
3.9. Site 5...........................................................................31
3.10. Site 6..........................................................................32
3.11. Site 7..........................................................................33
3.12. Site 8..........................................................................34
3.11. Site 9...........................................................................35
13.13 Site 10.........................................................................36
4.1. Image of tire marks taken at Site 7..............................................40
x


1. Introduction
Thousands of miles of urban trails wind their way through the United States.
Located in federal and state parks, as well as along urban corridors, these trails represent
typically a safe way for people to explore the outdoors. Denver, Colorado stands as a
prime example of an urban area with extensive trail development. With over one hundred
miles of trails zigzagging throughout the city, Denver provides many options for people
to travel away from roadways. The High Line Canal Trail, containing 66 useable miles
(106 km), snakes its way through the majority of Denver County (Water 2014). Though it
is convenient for people to use the trail, ecological impacts are not often considered. This
study looks into the impacts of anthropogenic pressures along the High Line Canal Trail
by assessing several different parameters.
This chapter introduces key components to this study. First, an understanding of
Rapid Ecological Assessments (REA) will be highlighted, with specific attention paid to
how REAs are used in a quick and efficient way and the application of such techniques
when surveying trails. Next, is a description of Wildland-Urban Interface (WUI) and how
the study area can be considered part of a WUI. Finally, before outlining the entire
thesiss structure, a brief discussion is offered relating to how home values can assist in
identifying any impacts to a trail based on economic values.
This study seeks to understand the impacts of urban trails along Wildland-Urban
Interface areas using Rapid Ecological Assessments that assess sediment disruption,
disturbed vegetation, bare ground, and vegetation density in relationship to property
values along the High Line Canal Trail.


1.1 Rapid Ecological Assessment
Many ecological studies require extensive time, resources, and a large budget. A
Rapid Ecological Assessment (REA) eliminates those factors and provides a sufficient,
yet brief, overview of a study area (Abate 1992, Preskitt, Vroom et al. 2004, Allen 2009,
Kotze, Ellery et al. 2012). This process examines ecological conditions resulting from
anthropogenic stressors. REAs can be an important management tool for biodiversity
protection, with easy implementation. And, according to Allen (2009), Medeiros (2013),
and Sayre (2000), REAs should be easy-to-use, non-invasive, inexpensive, and easily
replicable. This study uses an REA to examine various parameters along an urban trail
that fulfills those four requirements. It can be easily replicated to other urban trails world-
wide. Parameters assessed also include soil-vegetation interactions, which are important
conditions when examining multi-use recreational trails in urban areas (Roovers, Baeten
et al. 2004, Li, Ge et al. 2005, Allen 2009).
REAs were first implemented to examine habitats that require conservation
(Abate 1992, Medeiros and Torezan 2013), but REA studies now range from coral reefs
to forest conservation. REAs will be used in this study because it has broad applications,
and with proper scientific application, can be an efficient evaluation tool for ecological
health (Abate 1992, Sutula, Stein et al. 2006, Allen 2009, McHugh and Thompson 2011,
Kotze, Ellery et al. 2012, Medeiros and Torezan 2013).
1.2 Wildland-Urban Interface
The Wildland-Urban Interface represents an area where development meets
wildland vegetation (Monroe, Bowers et al. 2003, Vince, Duryea et al. 2004, Alavalapati,
Carter et al. 2005, Allen 2009). This interaction can result in several ecological hazards
2


including declines in biodiversity, wildlife populations being threatened, and
fragmentation and loss of habitats (Soule 1991, Pulido and Wolch 1996, McKinney 2002,
Radeloff, Hammer et al. 2005, Theobald and Romme 2007). The High Line Canal Trail is
an example of a trail that runs through a WUI. There is a band of vegetation that cuts
through human development with a trail in the middle. This vegetation corridor connects
fragmented habitats that have been disturbed because of development, but can also aid in
conserving flora, fauna, and soil resources, while also serving as a buffer for pollution
(Agriculture 2004).
In a recent survey, the High Line Canal Trail in Denver, Colorado has almost 200
species of birds, 28 different mammal species, and 15 varieties of reptiles (Water 2011).
In addition to the fauna, many native flora species exist as well, including the Plains
Cottonwood (Populus deltoides) and many varieties of grasses (blue grama and buffalo
grass, for example). There are also numerous non-native species also in abundance on the
trail, such as Russian Olive (Elaeagnus angustifolia), a small tree native to western and
central Asia that has outcompeted native vegetation because of its high reproductive rate
and ability to thrive in poor soil conditions. Another invasive and bothersome species
along the trail, the flowering plant Tribulus terrestris, is native to southern Europe and
Asia, and the seeds (commonly thought of as thorns), called goat heads, can puncture
bicycle tires. These seeds are most common in fall and winter and signs are posted along
the High Line Canal Trail warning about the damage that can be done to bikes. The threat
of human disturbance along the WUI can result in the spread of invasive and non-native
species (Trombulak and Frissell 2000, Alston and Richardson 2006, Buonopane, Snider
et al. 2013), and this has in fact happened with Tribulus. Because it has become so
3


common on the trail, it is considered invasive due to its ability to reproduce every year
without any outside assistance (such as a gardener planting the weed year after year)
(University 2013). This represents a prime example of an ecological niche interacting
with increasing human development forming a Wildland- Urban Interface (WUI) (Tyser
and Worley 1992, Radeloff, Hammer et al. 2005, Buonopane, Snider et al. 2013).
The High Line Canal corridor is no longer a haven for ecological development
and has resulted in potentially harmful interactions between humans and local wildlife.
While goat heads thorn cause damage to bike tires, people have also had encounters with
coyotes on the trail. Reports of coyotes attacking and injuring humans are uncommon,
but not rare. In 2011, a two-and-a-half-year old boy was attacked by a coyote in
Broomfield close to the High Line Canal. He was bit on the lower back, but had no
severe injuries (CBS 2011). Several dog-coyote encounters have also been reported.
Coyotes have been becoming more fearless towards humans because people have
allowed coyotes to become comfortable in their presence (Denver 2009). These types of
injuries and interactions have become more common and will likely continue to do so
with trail development interfering with ecosystems (Kasworm and Manley 1990, Tyser
and Worley 1992).
At WUI areas, the vegetation and animal communities tend to be more vulnerable
because of increase human presence (Wimberly, Zhang et al. 2006, McHugh and
Thompson 2011, Stella, Rodriguez-Gonzalez et al. 2013). This is why performing
ecological assessments of the High Line Canal Trail that runs through a WUI is necessary
to understand ecological impacts. There is not only human presence felt along the
periphery of the vegetation corridors, but also within the WUI.
4


1.3 Home Values
Home values can fluctuate between areas simple due to its walkability factor.
Walkability is the ease to which a person can walk to common conveniences, such as
shopping and social locations. Home values can increase drastically if located in a highly
walkable area (between $4,000 and $34,000) (Cortright 2009). The High Line Canal Trail
provides easy access to walking, biking, and even horse riding, which can potentially be a
factor of the home values adjacent to the trail because it is easier for residents to get
exercise (Lehman, Boyle et al. 2007, Rauterkus and Miller 2011).
Many individuals prefer to live close to wild space, yet still have convenience of
an urban or suburban setting (Alavalapati, Carter et al. 2005, Lange, Hehl-Lange et al.
2008). There is pressure to build along green space, but often ecological impacts are not
considered (Amati and Yokohari 2006, Gallent, Bianconi et al. 2006, Lange, Hehl-Lange
et al. 2008). This is why the area surrounding a WUI is important in development and
why home values might be higher in these areas.
1.4 Subsequent Chapters
The following chapters of this thesis examine the steps taken to conduct an REA
and the subsequent results. In thq Methods section, an exploration of the study site is
reviewed, followed by techniques used to gather the data. Additionally, the Methods give
an understanding of why specific parameters are chosen to be evaluated, as well as a
review of the statistical tests conducted. A very detailed Analysis of Results follows,
outlining and examining specific parameters in the context of data collected along at each
study site. Also included in this section are an image of each site location alongside any
related specific findings and highlighting any anomalous trends, as well as an overview
5


of home values along each site. The last chapter, Discussion and Recommendations,
elaborates on parts of the Analysis and Results, including a detailed discussion of the
statistical testing results and pertinence of home values to the study, with a special
section addressing societal applications. Finally, recommendations and future work are
discussed.
6


2. Introduction to Methods
This studys primary objective rests in identifying impacts of urban trail
development on local ecosystems, primary in sensitive riparian areas along the High Line
Canal Trail, comprising 66 miles (about 106 kilometers) of trail through Douglas,
Arapahoe, and Denver Counties in Colorado (Figure 2.1) (Water 2011).
Figure 2.1: A map showing all 71 miles of the High Line Canal Trail, broken
up into two sections: Lower (Eastern) and Upper (Western) Canal
(Bielenberg 2008). The numbers on the map correspond to the location of
each site studied.
7


This site was chosen because of its high pedestrian traffic through an urban center, which
can severely damage local ecology (Bhuju and Ohsawa 1998), and its close proximity to
a naturalized riparian area. The dry summer climate in Colorado, along with the trail
being on an urban fringe, can result in the soil and vegetation being sensitive to
disturbance. The data was collected on 10 separate days between August and October
2013. This ensured full vegetation coverage (if applicable) with little weather
interference. Though the High Line Canal is human built, it has been naturalized into the
local ecosystem over a span of 130 years, and is home to a variety of riparian biota
(Water 2011). This study closely follows the parameters for a Rapid Ecological
Assessment (REA) (Vanderhorst, Program, et al. 1993, Preskitt, Vroom et al. 2004, Allen
2009, McHugh and Thompson 2011, Kotze, Ellery et al. 2012, Medeiros and Torezan
(2013)), where only necessary and subjective data are collected pertaining to soil and
vegetation disturbance. Though there are several critics of REA and it should not be a
replacement for long-term field work, it is an efficient and quick way to assess the quality
of a site (Abate 1992).
2.1 Study Site
The High Line Canal Trail begins southwest of Denver, Colorado, close to
Chatfield Reservoir. The High Line Canal Trail runs through a Wildland-Urban Interface
(WUI) area because of its wildland ecology and location through urban development
(Theobald and Romme 2007). Between August and October, the average temperature
during the day ranges between 65 to 87 Fahrenheit with only about four inches of rain,
resulting in very dry soils (Denver). Along the Front Range, soils are primarily heavy
clays that can prevent water absorption and make it difficult for vegetation to grow.
8


Mineral salts and high pH (more basic) levels are other characteristics of soil in the
Denver area, and these too play a role in soil fertility (Pohly 2010). As the High Line
Canal Trail zigzags 71 miles (66 usable miles) through the area, its entire length was not
surveyed. Instead, ten equally-spaced one-kilometer sites were used as a proxy for the
trail, allowing for representation of the entire trail length without any bias. Starting with
kilometer three, each site is ten more kilometers than the previous site (Table 2.1).
Table 2.1. Location of the study areas along the High Line Canal Trail.
*Trail discontinues at 8.6 miles and starts back up at mile marker 9.6.
Site km marker (Mile Marker)
1 3-4 1.9-2.5
2 13-14 8.1-8.7*
3 23-24 14.3-14.9
4 33-34 20.5-21.1
5 43-44 26.7-27.3
6 53-54 32.9-33.5
7 63-64 39.1-39.7
8 73-74 45.4-46.0
9 83-84 51.6-52.1
10 93-94 57.8-58.4
9


At each one kilometer site, and based on a previous stratified random sample
method described by Allen (2009), Medeiros and Torezan (2013), and Preskitt, Vroom et
al. (2004), numbers between one and four were randomly drawn to determine the length
of time, in minutes, to walk before taking measurements, providing a stratified random
sample of the study area. Each stop along the one kilometer segment was considered a
transect of the site, consistent with terminology established in previous REA studies by
Medeiros and Torezan (2013) and Allen (2009). Several transects were described and
measured in each one kilometer site depending on the number drawn. For example, Site
1, between mile markers 1.9 and 2.5 (three and four kilometers), had four transects, while
Site 3, between mile markers 14.3 and 14.9 (23 and 24 kilometers) had six transects. This
depends entirely on the random process of pulling a number blindly out of a bag and
walking that designated length of time (in minutes) at each site until the full kilometer of
the representative section has been walked. At each transect, the canal and non-canal
sides of the trail were surveyed. Generally, the canal side of the trail is to the right of the
trail when increasing in mile marker numbers. The non-canal side of the trail is generally
the left side.
2.2 Data Gathering
The measurements on either side of the transect were obtained using a standard
25-foot tape measure. At each transect, parameters where measured at a half meter, one
meter, one-and-a-half meters, and two meters from the trails edge, resulting in precise
incremental data (Figure 2.2).
10


Legend: away from trail edge
Blue represents 1.5 2 meters
Orange represents 1-1.5 meters
Red represents 0.5 1 meter
Green represents 0 0.5 meters
Figure 2.2. Distances measured at the High Line Canal Trails edge.
Each parameter was assessed using a range of percentages (Table 2.2). This breakdown
of percentages is similar to the Index of Biotic Integrity (IBI) classes, though the
corresponding percentages are more applicable to general and multi-use recreational trail
REAs (Preskitt, Vroom et al. 2004, Allen 2009, McHugh and Thompson 2011, Kotze,
Ellery et al. 2012, Medeiros and Torezan 2013).
Table 2.2. Approximation of how each parameter is measured. NA indicates Not
Applicable and can refer to a) No vegetation present or b) The location cannot be
measured. A location cannot be measured if it is blocked by fence, or there is a steep
incline. 0 indicates there is no alteration to the parameter being measured. As an
example, 0 for Tree/Woody density indicates there is no tree/woody species present.
Value given Corresponding impact percentages
NA Not Applicable
0 None present
1 1-25%
2 26-50%
3 51-75%
4 76-100%
11


Each percentage range indicates each parameter in a specific transect on either side of the
trail. For example, a 2 for Disturbed Soil, Left side of transect and 0.5m indicates that
there is 26-50% disturbed soil on the non-canal side of the trail between 0 and 0.5 meters
away from the trails edge. Table 2.3 provides a visual representation of each
measurement.
Table 2.3. Visual representation of indicator values based on the parameter of vegetation
density.
0 indicator for vegetation density (no
vegetation present)
1 indicator value for vegetation density
(1-25%)
12


Table 2.3 (cont)
2 indicator value for vegetation density
(26-50%)
3 indicator value for vegetation density
(51-75%)
4 indicator value for vegetation density
(76-100%)
13


2.3 Parameters
Several parameters were measured to give a proper index of the trails quality and
follow other established REAs (Vanderhorst, Program, et al. 1993, Allen 2009, Medeiros
and Torezan 2013). These parameters include:
Soil Disruption
Disturbed Vegetation
Presence of Bare Ground
Tree/ Woody Vegetation Density
Grass/ Herbaceous Vegetation Density
Overall Disturbance
In some areas, a dominant plant species is also identified. The importance of identifying
dominant plants in each transect can assist in providing management techniques. The
presence of non-native and invasive species can quickly degrade the quality of the
ecology around the trail (Barbier, Knowler et al. 2013). A species is only collected for
identification if prominent floral characteristics are present. Choosing plants that can be
easily identified compliments the rapid ecological assessment at the study site by only
examining key impacts to the High Line Canal Trail (Vanderhorst, Program, et al. 1993).
Each of these parameters are measured at each transect on the canal side of the trail (right
side increasing in mile markers) and non-canal side at the pre-determined distances away
from the trail (Table 2.3).
14


Table 2.4. Matrix of each parameter along each transect for both sides of the High Line
Canal Trail. Note that a dominant species was not identified at each transect.
Time Multiplier ( _m)
0-.5 m 0.5 -1 m 1 1.5m 1.5 -2m
Disturbed soil Left
Right
Disturbed Left
vegetation Right
Bare Ground Left
Right
Tree/Woody Left
density Right
Grass density Left
Right
Disturbance Left
(Y/N) Right
Dominant Left
Species Right
15


2.4 Testing
To get a clear idea of any spatial trends, variations, and/or anomalies along the
High Line Canal Trail, each sites parameters were averaged. The canal side and non-
canal side were averaged separately to identify any separate trends that might be present.
Once averaged, a linear regression model was applied to determine any trends in the data.
A paired t-test is used for each parameter throughout the entire study area to calculate any
significance in the data between the canal side and non-canal side of the trail. In this
particular case, a paired t-test represents a strong method to detect differences on either
side of the High Line Canal Trail. A p-value is calculated, accepting or rejecting the null
hypothesis of
H P = P
ii0- A c A nc
where P indicates the mean of a specific parameter being tested, c representing the
canal side, and nc the non-canal side of the trail. While the experimental hypothesis is
H0: Pc 7-Pnc
The results will be significant if the resulting p-value is below the significance level of
0.05. The resultant value aids in determining if the parameters exhibit any statistical
significance.
Finally, each sites parameters are compared with the average home value of the
corresponding trail location. This is to determine if higher home values correlate with a


less natural, highly disturbed sections of the High Line Canal Trail. American Trails, a
non-profit organization, has shown that having walking areas close to neighborhoods
increases home values $4,000 to $34,000 compared to homes that do not offer such
walkability (Cortright 2009). The average home values along each study site are
determined by the website Trulia. As this study assesses trail impact at a popular, rapidly-
expanding Wildland-Urban Interface area in Denver, CO, gaining insights into property
values associated with it could influence future policies associated with land use,
development, and recreational opportunities.
17


3. Analysis of Results
The Rapid Ecological Assessment (REA) along the High Line Canal Trail
resulted in several noticeable and non-noticeable conclusions. Six parameters were
measured, but only four provided enough information to extrapolate important
characteristics of the trail. Tree/Woody density parameter resulted in little findings. Their
presence was found along the study area with leaf litter and shade, but could rarely be
indicated as a part of the assessment because the trunk or stem of the species was located
more than two kilometers away from the trail (outside the study area). Additionally,
overall disturbance parameter resulted in almost all transects at each site having some
kind of prominent disturbance. The main disturbance was grass cutting and pruning.
The remaining four parameters, disturbed soil, disturbed vegetation, bare ground,
and vegetation density, provided varying results throughout the study area. At each site,
transects were averaged (the canal and non-canal side separately) for the specific
parameter in question. The number of transects were randomly decided by picking a
number out of a hat and walking that distance in minutes until the full kilometer was
surveyed (Table 3.1). Figures 3.1-3.4 show the averaged values for each parameter at all
10 sites for both canal and non-canal sides of the trail. A linear regression line was added
to indicate any trends. The y-axis is valued 0-4, which is the range of percentages being
measured (Table 2.2).
First, the parameters (disturbed soil, disturbed vegetation, bare ground, and
vegetation density) will be examined. The site transects are averaged to obtain an
overview of the parameters at each site. The canal and non-canal side are calculated
18


separately to show any variation within a single site. A linear regression line is added to
observe general trends of each parameter along the High Line Canal Trail.
Next, a review of statistical analysis is discussed. A paired t-test is conducted on
the four parameters comparing the canal and non-canal side of the trail. The statistical
testing is significant if any prominent variability between the canal and non-canal side of
the trail at each site is found.
After a review of the parameters, each site is analyzed separately in conjunction
with its physical location along the trail. A satellite image is provided to get a clear
indication of factors that might influence the data collected and overall quality. Each site
is summarized by all six original parameters that include tree/woody density and overall
disturbance. The indicator values are discussed in reference to the parameters with a
comparison of the canal and non-canal side of the trail at each site.
Finally, a comparison of home values along the High Line Canal Trail study sites
is discussed, with the average home price compared to the overall trends at each site for
the four main parameters. This will show if home values play a direct role in the quality
of the ecology surrounding the High Line Canal Trail. The earlier hypothesis suggests
that with higher home values, the study sites along the trail will have more disruption. A
review for each analysis section will be discussed in the Discussion of Results, following
these analyses.
3.1 Number of Transects at each Site Location
The number of transects at each site location was determined by randomly picking
a number out of a hat that represents the length in minutes to walk to the next transect
19


location. This ensures that random data was collected to provide an accurate
representation of the trail. Each site had between four and six transects at the site (which
is one kilometer long).
Table 3.1. Number of transects at each site. This is determined by randomly being a
number out of a hat as a value for the number of minutes to walk between each transect
until one kilometer was studied.
Site location Number of Transects
1 4
2 4
3 5
4 5
5 6
6 6
7 6
8 5
9 5
10 5
20


3.1.1 Disturbed Soil
Figure 3.1. Average indicator values at each site for Disturbed Soil on the canal and non-
canal sides of the High Line Canal Trail. The green markers indicate a location where the
canal side and non-canal side of the trail have the same values.
The disturbed soil parameter measured any likely anthropogenic soil disruption.
The most disturbance of soil occurred 0 to 0.5 meters away from the trail. The linear
regression line shows that as the mile markers increase along the trail, the presence of
disturbed soil increased on the canal side of the trail. There are very drastic differences in
the indicator values between canal side and non-canal side of the trail in the same site.
The most apparent is site 7, which is between kilometers 63 and 73 on the High Line
Canal Trail. The non-canal side of the trail has a value of 0.208, while the canal side has
an average value of 2.13. This means that on the non-canal side there could be only 15%
overall soil disturbance, while the canal side could have as high as over 50% soil
disturbance.
21


At sites 8 and 10, the values for soil disturbance are very similar with 0.85 and
0.9, respectively. Sites 3 and 6 both have values of 0 for soil disturbance, indicating that
no soil disturbance was found on the respective sides of the trail. Overall, the canal side
had a higher rate of soil disturbance than the non-canal side of the trail based on the
linear regression model. The non-canal side remained relatively flat in the increase of soil
disturbance, while the regression line for the canal side shows a dramatic increase of soil
disturbance as the mile markers increase. A review of these results will be discussed in
the Discussion of Results Chapter.
3.1.2 Disturbed Vegetation
Disturbed Vegetation
Non-Canal
Canal
Linear (Non-Canal)
- Linear (Canal)
Figure 3.2. Average indicator values at each site for Disturbed Vegetation on the canal
and non-canal sides of the High Line Canal Trail. The green markers indicate a location
where the canal side and non-canal side of the trail have the same values.
The disturbed vegetation parameter displays very high values at each site along
the High Line Canal Trail. The lowest value is at site 1 on the non-canal side of the trail,
with just over 2. This represents a value between 26 and 50% of the vegetation at that site
22


on the non-canal side of the trail has disturbed vegetation. The highest values of disturbed
vegetation are shown between sites 4 and 8 (between kilometer 33 and 74 on the trail).
Four sites have indicator values of 4 (Site 4 non-canal side, Site 6 canal side, Site 7 -
canal and non-canal side), which represents 76-100% disturbance. The first two sites and
last two sites of the study have the overall lowest values of vegetation disturbance.
The linear regression lines exhibit an interesting trend for the canal and non-canal
side of the trail. Until site 6, the canal side had a greater value than the non-canal side for
disturbed vegetation. After site 6, the non-canal side had a greater value. This is likely
due to the large discrepancy between the canal side and non-canal side indicators at site
9. Site 9 has an indicator value of 2.5 for the canal side, while the non-canal side has a
value of 4. There is a pretty steady increasing trend of disturbed vegetation on the non-
canal side of the trail, while the canal side trend remains relatively flat.
23


3.1.3 Bare Ground
Bare Ground
Non-Canal
Canal
Linear (Non-Canal)
Linear (Canal)
Figure 3.3. Average indicator values at each site for Bare Ground on the canal and non-
canal sides of the High Line Canal Trail. The green markers indicate a location where the
canal side and non-canal side of the trail have the same values.
Bare ground represents an area where no vegetation is present, but there is also no
sign of disturbance. Bare ground differed between non-canal and canal side of the trail
considerably. Only at site 8, where the values were the same (1.75), did either side of the
trail have similar values. The largest area of discrepancy is at site 7, where the canal side
of the trail has an indicator value of about 3, but the non-canal side has an indicator value
less than 1. Site 8 has the same value for both the canal side and non-canal side of the
trail with 1.75 as well, meaning most of the site has between 30-45% bare ground.
Finally, site 10 shows the lowest amount of bare ground present at any of the study sites
for both sides of the trail. There was no site that had over an indicator value of 3,
meaning there was no site that averaged over 50% of bare ground.
24


The linear regression line for sides of the trail decrease as the mile markers along
the trail increase. Both lines begin very close to one another, but the non-canal side
regression line decreases much more rapidly than the canal side of the trail. The steep
decrease in the regression line represents lower indicator values for bare ground and is
likely the result of small values on the non-canal side at sites 7, 9, and 10.
3.1.4 Vegetation Density
Vegetation Density
Non-Canal
Canal
Linear (Non-Canal)
Linear (Canal)
Figure 3.4. Average indicator values at each site for Vegetation Density on the canal and
non-canal sides of the High Line Canal Trail.
Vegetation density demonstrates how much vegetation was present along the trail
at each site. Vegetation found along the High Line Canal Trail is primarly grasses.
Though herbaceous weeds and occasionally shrubs are also present, unquestionablly
Poaceae (Grass family) is the dominant vegetation. Site 7 has very low vegetation
25


density of the canal side, this complements the bare ground parameter that shows very
high bare ground on the canal side of the trail. Similar results are shown with the non-
canal side, too. On average, the canal side of the trail has lower vegetation density then
the non-canal side.
A linear regression trend of increasing vegetation density is observed for the canal
and non-canal sides of the trail. Each regression line began close to one another around
the second indicator (26-50%). Yet, the non-canal regression line increased more rapidly
than the canal line. The canal side stayed under 2.5, while the non-canal side rose above 3
(a 25% increase in vegetation cover).
3.2 Statistical Testing
A paired t-test was conducted for each parameter comparing the canal and non-
canal side of the trail at all 10 site locations along the High Line Canal Trail. Each test
provided no statistically significant results. This concludes the evidence that there is
insufficient data to reject the null hypothesis (H0: Pc = Pnc) as mentioned in the Methods
section of this paper. It is unlikely that the canal side and non-canal side of the trail differ
significantly.
3.3 Site Locations
Each of the 10 site locations are shown below. The aerial map provides insight as
to the quality and terrain surrounding the High Line Canal Trail. The green dash marks
on the map show the exact location of the site studied. Each green marker is
26


approximately one kilometer long, the length of each site. As a reminder, the canal side
of the trail is to the right and the non-canal side is to the left for perspective.
3.3.1 Site 1
Figure 3.5. Site 1 of the High Line Canal Trail located kilometers 3-4. The green
dashed line represents the location of the Trail study area.
Site 1 is located between 3 and 4 kilometers on the High Line Canal Trail (mile
marker 1.9-2.5). There were a total of four transects that were studied at this location.
Varying results were seen between each transect. The second transect was the only one
that had very high disturbed soil (an indicator of 4). All other transects at this site only
had an indicator of 1 for disturbed soil. There was only one woody plant observed at this
site. It was located in the third transect, 1.5 meters away from the trail on the non-canal
side. The second transect, on the canal side of the trail, had very little vegetation present.
27


Overall, Site 1 had minimal anthropogenic impact, particularly compared to the other
study sites.
3.3.2 Site 2
Figure 3.6. Site 2 of the High Line Canal Trail located kilometers 13-14. The
green dashed line represents the location of the Trail study area.
Site 2 is located between kilometer 13 and 14 on the trail (mile marker 8.1-8.7).
The survey of this site was reduced by one-tenth of a mile because the trail briefly
discontinued at mile marker 8.6. Site 2 also had four transects. The only tree/woody
species present was located in the third transect, one meter away from the trail on the
canal side. Most transects had some kind of disturbed vegetation, primarily from
mowing, except for the canal side of the second transect that had no vegetation
disturbance.
28


3.3.3 Site 3
Figure 3.7. Site 3 of the High Line Canal Trail located kilometers 23-24. The
green dashed line represents the location of the Trail study area.
Site 3 is located at kilometers 23-33 on the Trail (mile marker 14.3-14.9). There
were five transects studied along this site. For most of the site, there was a slope coming
down to the trail on the non-canal side and a slope going from the trail to the canal on the
other side. This varying terrain impacted the parameters observed. Similar to the last
sites, site 3 only has one documented tree/woody vegetation species. At the third transect
on the non-canal side, there is no vegetation present and all the soil has been disturbed,
mainly due to much mowed grass.
29


3.3.4 Site 4
Figure 3.8. Site 4 of the High Line Canal Trail located kilometers 33-34. The
green dashed line represents the location of the Trail study area.
Site 4 is located at kilometer 33-34 (mile marker 20.5-21.1) on the High Line
Canal Trail. This site had five transects documented. For most of the site, very little
disturbed soil was documented. Vegetation disturbance, on the other hand, was extremely
high, with each transect averaging an indicator of four, yet no tree/woody species was
document along this segment of the trail. There were variations in bare ground and thus
variations in vegetation density, ranging from zero to an indicator of four. The third
transect of the site was very close to a road and likely influenced the parameters with
almost 100% disturbed vegetation. The last transect had documentation of tire tracts
along the trail, likely for maintenance including mowing along the trail.
30


3.3.5 Site 5
Figure 3.9. Site 5 of the High Line Canal Trail located kilometers 43-44. The
green dashed line represents the location of the Trail study area.
Site 5 is located between kilometers 43-44 (mile marker 26.7-27.3), and six
transects were studied. Each transect, except for the fourth, had high levels of disturbed
soil on the canal side of the trail. The non-canal side had very little soil disturbance,
likely because it was on a slope for most of the site. Again, there were no tree/woody
species documented throughout the site. Also, similar to the previous sites, this site
exhibited an average of 76-100% disturbed vegetation. Overall, the vegetation density
was much higher on the non-canal side of the trail then the canal side.
31


3.3.6 Site 6
Figure 3.10. Site 6 of the High Line Canal Trail located kilometers 53-54. The
green dashed line represents the location of the Trail study area.
Comprised of six transects, site 6 is located between kilometers 53-54 (mile
markers 32.9-33.5). Throughout all transects, no tree/woody vegetation was documented.
The second and fourth transects could only be measured one meter away from the trail on
the canal side because of a steep slope leading into the canal. Each transect had very high
indicators of vegetation density, likely resulting in the low indicators for disturbed soil
and bare ground. Overall, site 6 had high human impact and experienced high
disturbances.
32


3.3.7 Site 7
Figure 3.11. Site 7 of the High Line Canal Trail located kilometers 63-64. The
green dashed line represents the location of the Trail study area.
Site 7 is located between kilometers 63-64 (mile markers 32.9-33.5) and contains
six transects. Populus deltoides (Cottonwood) was identified in the fourth transect two
meters away on the canal side of the trail. The study site had extreme differences between
the canal side and non-canal side of the trail. The canal side has very high indicators for
bare ground, while the non-canal side had very few areas with bare ground. This is
because of a dirt path that ran parallel to the trail on the canal side. Tire tracks were
noticeable and the path was likely for maintenance vehicles. A large anthropogenic
presence was observed at this site, more so than any other study site along the High Line
Canal Trail, but the disturbance was primarily from the mowing of vegetation along the
trail.
33


3.3.8 Site 8
Site 8 is located between kilometers 73-74 (mile markers 45.4-46.0) on the High
Line Canal Trail, and comprises five transects. Though there were no tree/woody species
present along the two meter parameter of the trail in site 8, a large cottonwood was
overhanging the canal side trail segment of the fourth transect. This could have
contributed to lower vegetation density and higher bare ground in this transect because
vegetation could be covered with leaf litter, making it difficult to grow. Poaceae
dominated vegetation at this site, except at the fifth transect where Tribulus terrestris
(Goat head thorn) was found at very high amounts. This is an incredibly invasive weed
producing seeds that can puncture bike tires. Overall, Site 8 had high anthropogenic
disturbance.
34


Figure 3.13. Site 9 of the High Line Canal Trail located kilometers 83-84. The
green dashed line represents the location of the Trail study area.
Consisting of five transects, site 9 is located at kilometers 83-84 (mile markers
51.6-52.1) on the High Line Canal Trail. No tree/woody species was documented at this
site. At this site, the trail split into two sections, an upper dirt path and a lower paved path
at transects three, four, and five. The data collected was only from the paved part of the
trail and there is no documentation of the parameters on the unpaved path. Also at the
third transect, a fence located on the non-canal side of the trail blocked the ability to
collect data between 1.5 and two meters. There was very little disturbed soil documented
along the entire site, only at transects one and four on the canal side of the trail were there
high indicators of soil disturbance. Overall site 9 showed high levels of human
disturbance.
35


3.3.10 Site 10
Figure 13. Site 10 of the High Line Canal Trail located kilometers 93-94. The
green dashed line represents the location of the Trail study area.
Site 10 is located at kilometers 93-94 (mile markers 57.8-58.4) along the High
Line Canal Trail, and contained five transects. Again, there is no documentation of
tree/woody species located along the trail. At transect one, there was Pinusponderosa
(Ponderosa Pine) needles along the non-canal side of the trail, but this did not impact the
vegetation density of the transect. There was very high vegetation densities found
throughout the trail, except for transect two, which had no vegetation on either side of the
trail until 1.5 meters. At transect three, as with site 9, the trail split into an unpaved and
paved section, but data was only collected on the paved portion. Overall, there was
significant anthropogenic disturbance along the trail. At each transect, concrete pieces
were found along the trails edge.
36


3.4 Home Values
Average home values for each site was calculated to determine if an area with
high home value has higher instances of trail disturbance along the High Line Canal Trail
and is noted in Table 3.2. The site with the highest home value is site 6, located in Cherry
Hills Village with the average home cost along the canal being $3,300,000. Site 6 has
high average rates of bare ground and disturbed soil, but has one of the lowest overall
indicators for disturbed soil on the canal and non-canal side of the trail. Located in
Denver County, site 7, with the third-lowest average home values at $369,000, shows the
highest indicator of overall disturbance in each parameter. Based off of a simple
comparison between home value prices along the canal and parameter values, there is
likely no correlation between home value price and trail disturbance.
Table 3.2. Average home values at each site along the High Line Canal Trail.
Site Average Home value ($) Location
1 400,000 Douglas County
2 426,000 Douglas County
3 600,000 Highlands Ranch
4 349,000 Littleton
5 1,088,000 Greenwood Village
6 3,300,000 Cherry Hills Village
7 369,000 Denver County
8 370,000 Arapahoe County
9 124,000 Aurora Hills Golf Course
10 158,000 Laredo Highline
37


4. Discussion and Recommendations
Analyzing background information and methods used to create and implement a
Rapid Ecological Assessment (REA) along the Wildland Urban Interface (WUI), this
chapter discusses results pertaining to societal applications, and offers recommendations
for this research project and suggests directions for future studies. To accomplish these
goals, this chapter begins with a discussion of the analysis that identifies overall trends in
the data (parameters, statistical testing, and home values) while also offering potential
explanations of factors that could have contributed to the results. Then, societal
applications of the REA in relation to how the research techniques employed in this study
can be applied to other urban trails is offered. Finally, the chapter ends with an in-depth
summary outlining possible shortcomings, as well as future opportunities and their
implications.
4.1 Discussion of Analysis
This section focuses on the High Line Canal Trails overall trail health based on
several parameters. First, the four parameters are examined and extrapolations of the data
will be made to discern any potential reasons for trail quality. Next, a review of statistical
analysis is offered to help identify if the canal and non-canal sides of the trail
significantly differ for each parameter. Additionally, this underscores potential reasons
for indicator values at site locations. That is, it will provide a speculation as to why
various parameters have specific indicator values. Finally, an evaluation of home values
in reference to site locations along the High Line Canal Trail is reviewed. This is
important to the study because it identifies if there are economic factors that contribute to
38


trail disturbance. Each section also provides an appropriate conclusion in regards to
anthropogenic impacts on the High Line Canal Trail.
4.1.1 Parameters
There were four primary parameters that were assessed along the High Line Canal
Trail: Bare Ground, Disturbed Vegetation, Vegetation Density, and Disturbed Soil. Each
parameter resulted in varying conclusions about the overall quality of the High Line
Canal Trail at each site. Sites that have high indicator values for a parameter will be
evaluated.
First, Disturbed Soil had overall low indicator values. This is likely because the
High Line Canal Trail was either paved (majority of the trail) or was gravel. Through on
the ground data collection and observations, it was noticed that there was minimal direct
human impact off the paved or graveled trail. Based on visual evidence as recorded in the
REA matrices, the likely reason for any disturbance is because of pets and maintenance
for the trails. Many dogs have the freedom by their owners to walk off the path both on or
off a leash (Reynolds, Wolch et al. 2007). Additionally, maintenance trucks easily disturb
soil. This is the case at site 7 along the canal side of the trail, where visible tire tracks can
be seen while performing the Rapid Ecological Assessment (Figure 4.1).
39


Figure 14. Image of tire marks taken at Site 7.
Second, the Disturbed Vegetation parameter exhibited high indicators at each site
surveyed. As noted in the REA matrices, this is likely due to on-the-trail maintenance.
The vegetation had clearly been mowed, particularly when a street or activity area/park
was close to the trail. This is the case with the non-canal side at Site 9, which borders a
large fenced-in green space. At Site 7, an indicator value of 4 for both the canal and non-
canal side of the trail was likely due to the proximity of the trail to Interstate 25. Safety is
a primary factor of mowing vegetation, because of potential harmful interactions with
wildlife and humans. In general, disturbed vegetation rates were high on both canal and
non-canal sides of the trail, and typically, closer to the canal had lower vegetation
disturbance. As a reminder, the study area was two meters on either side of the trail.
Additionally, the low rates of disturbed vegetation at site 1 and 10 are likely because
there is not much development in the area resulting in a smaller maintenance presence.
40


Third, some anomalous readings were present when assessing Bare Ground. As
mentioned previously, Site 1 had very little vegetation, which is why the indicator values
are high for Bare Ground at that site. Also, there are large discrepancies at Site 7 and 9
between the canal and non-canal sides of the trail, but this is primarily because of the
presence of maintenance vehicle tracks, with visible tire marks seen at both locations
(Figure 14).
Finally, Vegetation Density fluctuates a great deal between canal and non-canal
sides of the trail. As with past parameters, presence of maintenance vehicles and
proximity to streets can all be influential to vegetation density. A general increase in
vegetation density along the High Line Canal Trail is likely due to closer proximity to
humans, which can result in more vegetation to be planted along the trail. This increase in
vegetation density is likely just for aesthetic appeal.
4.1.2 Statistical Testing
The results of the paired t-test on the four parameters concluded there was no
statistically significant difference between the canal and non-canal sides of the trail. For
each parameter, there was insufficient data to reject the null hypothesis of the canal side
and non-canal sides of the trail to be equal. These results demonstrate that even though
some fluctuations between the canal and non-canal sides of the trail for each parameter
were discovered, there were no significant disparities between the sides of the High Line
Canal Trail. This is likely due to the small perimeter around the trail that was tested (two
meters on either side). Judging from field-based observations, if data were collected up to
five meters on either side of the trail, there would potentially be more discrepancies
41


between the two sides, and perhaps even a statistically significant trend that could help
predict impact of trail use at the WUI.
4.1.3 Home Values
The average home values along each site at the High Line Canal Trail assist in
identifying any impacts to the trail based on economic values. Once analysis of site
locations and home prices were compared, it seems that little correlation is present (Table
3.2).
It is likely that the trail is more impacted by proximity to streets and high human
traffic than wealth of an area as found in other studies (Marion and Leung 2001,
Alavalapati, Carter et al. 2005, Allen 2009, Cortright 2009, McHugh and Thompson
2011, Buonopane, Snider et al. 2013). Even in sites with very high home values, trail
parameters did not differ considerably from sites with low home values, and, as with
other parameters, the largest discrepancies occurred in areas with a high volume of
human and vehicle traffic and varying vegetation growth.
4.2 Societal Applications
It is important to note the necessary balance that must be present between humans
and the ecosystem, particularly on trails through WUI areas. These areas are susceptible
to high amounts of pollution (trash), contaminants (pet feces), invasive plant species
(escaped horticults), and overall disturbance (human presence) (EPA 2013).
There is a severe lack of policy regarding trail development, particularly trails that
run through WUIs. The desire to have more outdoor opportunities has overshadowed
potential issues to the ecosystem due to development (Bhuju and Ohsawa 1998, Marion
42


and Leung 2001). More policy should be enacted to allow regulations in trail
development (McHugh and Thompson 2011, Denver 2012). Based on the findings of
Bhuju and Ohsawa (1998) and Kotze, Ellery et al. (2012) findings, REAs can be
beneficial in helping establish environmentally-friendly multi-use trails. It is a quick and
efficient way to provide an overall quality assessment of the area (Vanderhorst, Program,
et al. 1993, Preskitt, Vroom et al. 2004, Kotze, Ellery et al. 2012, Medeiros and Torezan
2013). Regardless of the location of a trail (urban, rural, etc.), natural ecosystems will be
impacted because of the increase presence of anthropogenic factors. Trails that run
through WUTs are more likely to cause ecological harm because they are on the human-
wildland interface (Bhuju and Ohsawa 1998, Marion and Leung 2001, Wimberly, Zhang
et al. 2006, Theobald and Romme 2007, Buonopane, Snider et al. 2013). Additionally,
monitoring and unified management techniques of the trail are necessary to maintain
ecological health (Marion and Leung 2001, McHugh and Thompson 2011). The High
Line Canal is managed only by Denver Water, but the trail is managed by different
communities in which it passes. According to Denver Water (2014), there are seven
agencies that oversee the High Line Canal Trail. Various management techniques exist
between the different agencies, when one comprehensive organization should maintain
the quality of the High Line Canal Trail.
Public outreach and education is one way to promote a more environmentally
conscious individual (Martin, Sorice et al. 2013). Educational programs and outreach that
incorporate local organizations and home owners along the trail can provide increase
support for trail management and upkeep, including education about invasive and non-
native plant species and its impacts. And by using REAs, it makes the data more
43


accessible to communities members and policy makers (Schiller, Hunsaker et al. 2001,
Allen 2009).
4.3 Future Work and Recommendations
This rapid ecological assessment conducted on the High Line Canal Trail serves
as a brief synopsis of the overall quality of the trail. Due to time and financial limitations,
there are several aspects of this project that can be explored by future researchers.
Although REAs should not be a replacement for long-term field studies, they are
effective tool that can provide broad conclusions about an area (Abate 1992). For this
reason, an REA was designed for this project, and highlights the importance of REAs for
management purposes, along with its ease of use. Limited data was collected in a short
period of time to provide a general assessment of the trail, but more in depth research
could be collected and provide more detailed data that possibly could lead to better
explanations and specific trends. REAs could be implemented to other urban trails
around the County to provide a basis for trail quality in areas of high anthropogenic
impacts. For example, Denver has five major trails, Cherry Creek, Bear Creek, High Line
Canal, South Platte River, and Sand Creek Trail. REAs could be conducted on each trail
and compared to another citys trail assessment, providing potential management
techniques for cities that have high disturbance values.
In terms of overall investigation, several factors were discovered that could have
hindered the extent of analysis. First, the restricted size of the canal and non-canal side
measurement areas was limited. Only two meters on either side were measured, but in the
future, it would be more beneficial to obtain data as much as five meters on either side of
44


the trail. This would potentially strengthen the similarities or differences found in the data
between each the canal and non-canal sides of the trail. Second, the entire trail length
could be analyzed, breaking the sites into single-kilometer segments or by designated
neighborhood/green space/park space. Of course this would require much more time, but
could still be efficiently done using an REA.
Overall, the data collected along the High Line Canal Trail provides an insight to
the issues surrounding a trail that runs through a WUI. Using an REA provided a quick
and straight forward survey of parameters often used to indicate trail impacts (bare
ground, disturbed soil, disturbed vegetation, and vegetation density). The study followed
previously established REA guidelines (Abate 1992, Preskitt, Vroom et al. 2004, Allen
2009, McHugh and Thompson 2011, Kotze, Ellery et al. 2012) but it is the first of its
kind to study a trail that has very heavy anthropogenic impacts and runs through a WUI.
Future researchers can use this study as a base from which to draw upon when assessing
other WUI areas, and gain a general overview of potential trail impact, and these findings
could influence future management plans. In the end, this studys importance rests in
highlighting main impacts of trail development through a WUI using the straightforward
technique of a Rapid Ecological Assessment that can be performed with limited time and
budget to gain insight to potential ecological disturbances. The REA parameters
mentioned in this study can be a basis for other world-wide studies to replicate potential
anthropogenic impacts on an urban trail and identify if there are economic ties to
ecological health.
45


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Appendix
A. Site Worksheet
*SITE
Transect (A)Time Multiolier ( m) .5 m 1 m 1.5m 2m (B)Time Multiolier ( m) .5 m 1 m 1.5m 2m
Left Disturbed soil Right
Disturbed Left vegetation Right
Left Bare Ground Right
Tree/ Woody Left density Right
Left Grass density Right
Disturbance Left (Y/N) Right
"Dominate Left Species Right

Time Multiolier ( m) .5 m 1 m 1.5m 2m (D)Time Multiolier ( m) .5 m 1 m 1.5m 2m
Left Disturbed soil Right
Disturbed Left vegetation Right
Left Bare Ground Right
Tree/ Woody Left density Right
Left Grass density Right
Disturbance Left (Y/N) Right
"Dominate Left Species Right

(E)Time Multiolier ( m) .5 m 1 m 1.5m 2m (F)Time Multiolier ( m) .5 m 1 m 1.5m 2m
Left Disturbed soil Right
Disturbed Left vegetation Right
Left Bare Ground Right
Tree/ Woody Left density Right
Left Grass density Right
Disturbance Left (Y/N) Right
"Dominate Left Species Right
Average home value for site:


B. In-the field Worksheet Example


Full Text

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CREATING A RAPID ECOLOGICAL ASSESSMENT FOR ANTHROPOGENIC IMPACTS: AN EXAMINATION OF THE HIGH LINE CANAL TRAIL By REBECCA MARIE HAYS B.A., The George Washington University, 2010 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment O f the requirements for the degree of Masters of Science Environmental Sciences 2014

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ii This thesis for the Masters of Science degree by Rebecca Marie Hays has been approved for the Environmental Sciences Program b y Casey Allen, Chair Gregory Simon Jon Barbour April 30, 2014

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iii Hays, Rebecca Marie (Master, Environmental Sciences) Creating a Rapid Ecological Assessment for Anthropogenic Impacts: An Examination of the High Line Canal Trail Thesis directed by Assistant Professor Casey Allen. ABSTRACT Similar to other urban areas around the United States, Denver, CO provides many outdoor trail opportunities that interact with t he urban landscape. The High Line Canal Trail is one such trail example that goes through a Wildland Urban Interface (WUI). This study evaluates the High Line Canal Trail using the straight forward technique of a Rapid Ecological Assessment (REA) to understand the anthropogenic impacts along a multi use trail. This study surveyed ten, one kilometer segme nts spaced out in ten kilometer increments for the duration of the High Line Canal Trail (total length approximately 66 miles/106 km). This allows for a random sampling of the trail, while maintaining time and budget constraints. Testing of the study area was conducted between August and October, 2013 to ensure full vegetation growth with little weather interference. Several parameters were examined using REA: soil disruption, disturbed vegetation, bare ground, and vegetation density, including the relation ship of these parameters with property values along the trail. Additionally, a paired t test was used to evaluate any significance between the canal and non canal side of the trail of each parameter. These parameters revealed overall anthropogenic disturba nce along the High Line Canal Trail, particularly with the vegetation disturbance parameter, though little correlation between any type of disturbance and regarding property values was found. Similarly, no significance was found between the canal and non c anal side of the trail. This study, however,

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iv provides an important basis for assessing urban trail interactions with an eye towards comprehensive management in WUI areas. It is easy to replicate and can be the basis for assessments along any urban trail. The form and content of this abstract are approved. I recommend its publication. Approved: Casey Allen

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v DEDICATION I dedicate this work to my loving family for always believing I can succeed

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vi ACKNOWLEDGMENTS I would like to thank Dr. Casey Allen for being an excellent advisor This thesis would never have come together without him. I would also like to give special acknowledgement to Jordan Cohen and Hannah Edmond for being amazing field assistants

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vii TABLE OF CONTENTS Chapter 1.Introduction ................................ ................................ ................................ ................................ ... 1 1.1 Rapid Ecological Assessment ................................ ................................ ................................ 2 1.2. Wildland Urban Interface . 2 1.3 Home Values ................................ ................................ ................................ .......................... 5 1.4 Subsequent Chapters ................................ ................................ ................................ .............. 5 2. Introduction to Methods ................................ ................................ ................................ ............... 7 2.1Study Site ................................ ................................ ................................ ................................ 8 2.2 Data Gatheri ng ................................ ................................ ................................ ..................... 10 2.3 Parameters ................................ ................................ ................................ ............................ 14 2.4 Testing ................................ ................................ ................................ ................................ 16 3. Analysis of Results ................................ ................................ ................................ .................... 18 3.1 Number of Transects at each Site Location ................................ ................................ ......... 19 3.1.1 Disturbed Soil ................................ ................................ ................................ ............... 21 3.1.2 Disturbed Vegetation ................................ ................................ ................................ .... 22 3.1.3 Bare Ground ................................ ................................ ................................ .................. 24 3.1.4 Vege tation Density ................................ ................................ ................................ ........ 25 3.2 Statistical Testing ................................ ................................ ................................ ................. 26 3.3 Site L ocations ................................ ................................ ................................ ...................... 26 3.3.1 Site 1 ................................ ................................ ................................ ............................. 27 3.3.2 Site 2 ................................ ................................ ................................ ............................. 28 3.3.3 Site 3 ................................ ................................ ................................ ............................. 29 3.3.4 Site 4 ................................ ................................ ................................ ............................. 30 3.3.5 Site 5 ................................ ................................ ................................ ............................. 31 3.3.6 Site 6 ................................ ................................ ................................ ............................. 32 3.3.7 Site 7 ................................ ................................ ................................ ............................. 33 3.3.8 Site 8 ................................ ................................ ................................ ............................. 34 3.3.9 Site 9 ................................ ................................ ................................ ............................. 35 3.3.10 Site 10 ................................ ................................ ................................ ......................... 36 3.4 Home V alues ................................ ................................ ................................ ........................ 37 4. Discussion and Recommendations ................................ ................................ ............................. 38

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viii 4.1 Discussion of Analysis ................................ ................................ ................................ ......... 38 4.1.1 Parameters ................................ ................................ ................................ ..................... 39 4.1.2 Statistical Testing ................................ ................................ ................................ .......... 41 4.1.3 Home Values ................................ ................................ ................................ ................. 42 4.2 Societ al Applications ................................ ................................ ................................ ........... 42 4.3 Future Work and Recommendations ................................ ................................ .................... 44 Appendix A.Site Worksheet ................................ ................................ ................................ ........................... 51 B. In the field Worksheet Example ................................ ................................ ............................. 52 References ................................ ................................ ................................ ................................ ...... 46

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ix LIST OF TABLES Table 2.1. Location of the study areas along the High Line Canal Trail. ................................ ..... 9 2.2. Approximation of how each parameter is measured. ................................ ................. 11 2.3. Visual representation of indicator values ................................ ................................ ... 12 2.4. Matrix of each parameter ................................ ................................ ........................... 15

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x LIST OF FIGURES Figure 2.1 : A map showing all 71 mil es of the High Line Canal Trail ................................ ......... 7 ................................ ......... 11 3 3.2. Average indicator values at each site for Disturbed Vegetation. ............................... 22 3.3 3.4. Average indicator values at each site for Vegetation Density. ................................ .. 25 3.5. Site 1. ................................ ................................ ................................ ......................... 27 3.6. Site 2. ................................ ................................ ................................ ......................... 28 3.7. Site 3 ................................ ................................ ................................ .......................... 29 3.8. Site 4 ................................ ................................ ................................ .......................... 30 3.9. Site 5 ................................ ................................ ................................ .......................... 31 3.10. Site 6. ................................ ................................ ................................ ....................... 32 3.11. Site 7 ................................ ................................ ................................ ........................ 33 3.12. Site 8. ................................ ................................ ................................ ....................... 34 3.11. Site 9 ..35 13. 13 Site 10 ................................ ................................ ................................ ..................... 36 4.1. Image of tire marks taken at Site 7. ................................ ................................ ........... 40

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1. Introduction Thousands of miles of urban trails wind their way through the United States. Located in federal and state parks, as well as along urban corridors, these trails represent typically a safe way for people to explore the outdoors. Denver, Colorado stands as a prime example of an urban area with extensive trail development. With over one hundred miles of trails zigzagging throughout the city, Denver provides many options for people to travel away from roadway s. The High Line Canal Trail, containing 66 useable miles (106 km) snakes its way through the majority of Denver County ( Water 2014 ) Though it is convenient for people to use the trail, ecological impacts are not often conside red. This study looks into the impacts of anthropogenic pressures along the High Line Canal Trail b y assessing several different parameters. This chapter introduces key components to this study. First, an understanding of Rapid Ecological Assessments (REA) will be highlighted, with specific attention paid to how REAs are used in a quick and efficient way and the application of such techniques when surveying trails. Next, is a description of Wildland Urban Interface (WUI) and how the study area can be considered part of a WUI. Finally, before outlining the entire s offered relating to how home values can assist in identifying any impacts to a trail based on economic values. This study seeks to understand the impacts of urban trails along Wildland Urban Interface areas usin g Rapid Ecological Assessments that assess sediment disruption, disturbed vegetation, bare ground, and vegetation density in relationship to property values along the High Line Canal Trail.

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2 1.1 Rapid Ecological Assessment Many ecological studies require extensive time, resources, and a large budget. A Rapid Ecological Assessment (REA) eliminates those factors and provides a sufficient, yet brief, overview of a study area ( Abate 1992 Preskitt, Vroom et al. 2004 Allen 2009 Kotze, Ellery et al. 2012 ) This process examines ecological conditions resulting from protection, with easy implementation. And, according to Allen (2009), Medeiros ( 2013 ) and Sayre ( 2000 ) be easy to use, non invasive, inexpensive, and easily replicable. This study uses an REA to examine various parameters along an urban trail that fulfills those four requirements. It can be easily replicated to other urban trails world wide. Parameters asse ssed also include soil vegetation interactions, which are important conditions when examining multi use recreational trails in urban areas ( Roovers, Baeten et a l. 2004 Li, Ge et al. 2005 Allen 2009 ) ( Abate 1992 Medeiros and Torezan 2013 ) but REA studies now range from coral reefs and with proper scientific application, can be an efficient evaluation tool for ecological health ( Abate 1992 Sutula, Stein et al. 20 06 Allen 2009 McHugh and Thompson 2011 Kotze, Ellery et al. 2012 Medeiros and Torezan 2013 ) 1.2 Wildland Urban Interface The Wildland Urban Interface represents an area where development meets wildland vegetation ( Monroe, Bowers et al. 2003 Vince, Duryea et al. 2004 Alavalapati, Carter et al. 2005 Allen 2009 ) This interaction can result in several ecological hazards

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3 including declines in biodiversity, wildlife populations being threatened, and fragmentation and loss of habitats ( Soule 1991 Pulido and Wolch 1996 McKinney 2002 Radeloff, Hammer et al. 2005 Theobald and Romme 2007 ) The High Line Canal Trail is an example of a trail that runs through a WUI. There is a band of vegetation that cuts through human development with a trail in the middle. This vegetation corridor connects f ragmented habitats that have been disturbed because of development, but can also aid in conserving flora, fauna, and soil resources, while also serving as a buffer for pollution ( Agriculture 2004 ) In a recent survey, the Hi gh Line Canal Trail in Denver, Colorado has almost 200 species of birds, 28 different mammal species, and 15 varieties of reptiles ( Water 2011 ) In addition to the fauna, many native flora species exist as well, including the Plains Cottonwood ( Populus deltoides ) and many varieties of grasses (blue grama and buffalo grass, for example). There are also numerous non native species also in abundance on the trail, such as Russian Olive ( Elaeagnus angustifolia ), a small tree native to western and central Asia that has outcompeted native vegetation b ecause of its high reproductive rate and ability to thrive in poor soil conditions. Another invasive and bothersome species along the trail, the flowering plant Tribulus terrestris is native to southern Europe and Asia, and the seeds (commonly thought of bicycle tires. These seeds are most common in fall and winter and signs are posted along the High Line Canal Trail warning about the damage that can be done to bikes. The threat of human disturbance along the W UI can result in the spread of invasive and non native species ( Trombulak and Frissell 2000 Alston and Richardson 2006 Buonopane, Snider et al. 2013 ) and this has in fact happened with Tribulus Because it has become so

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4 common on the trail, it is considered invasive due to its ability to reproduce every year without any outside assistance (such as a gardener planting the weed year after year) ( University 2013 ) This represents a prime example of an ecological niche interacting with in creasing human development forming a Wildland Urban Interface (WUI) ( Tyser and Worley 1992 Radeloff, Hammer et al. 2005 Buonopane, Snider et al. 2013 ) The High Line Canal corridor is no longer a haven for ecological development and has resulted in potentially harmful interactions betw een humans and local wildlife. While goat heads thorn cause damage to bike tires, people have also had encounters with coyotes on the trail. Reports of coyotes attacking and injuring humans are uncommon, but not rare. In 2011, a two and a half year old boy was attacked by a coyote in Broomfield close to the High Line Canal. He was bit on the lower back, but had no severe injuries ( CBS 2011 ) Several dog coyote encounters have also been reported. Coyotes have been becoming ( Denver 2009 ) These types of injuries and interactions have become more common and will likely continue to do so with trail development interfering with ecosystems ( Kasworm and Manley 1990 Tyser and Worley 1992 ) At WUI areas, the vegetation and animal communities tend to be more vulnerable because of increase human presence ( Wimberly, Zhang et al. 2006 McHugh and Thompson 2011 Stella, Rodrguez Gonzlez et al. 2013 ) This is why performing ecological assessments of the High Line Canal Trail that runs through a WUI is necessary to understand ecological impacts. There is not only human presence felt along the periphery of the vegetation corridors, but also within the WUI.

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5 1.3 Home Values Home values can fluctuate between areas simple due to its walkability factor. Walkability is the ease to which a person can walk to common conveniences, such as shopping and social locati ons. Home values can increase drastically if located in a highly walkable area (between $4,000 and $34,000) ( Cortright 2009 ) Th e High Line Canal Trail provides easy access to walking, biking, and even horse riding, which can potentially be a factor of the home values adjacent to the trail because it is easier for residents to get exercise ( Lehman, Boyle et al. 2007 Rauterkus and Miller 2011 ) Many individuals prefer to live close to wild space, yet still have convenience of an urban or suburban setting ( Alavalapati, Carter et al 2005 Lange, Hehl Lange et al. 2008 ) There i s pressure to build along green space, but often ecological impacts are not considered ( Amati and Yokohari 2006 Gallent, Bianconi et al. 2006 Lange, Hehl Lange et al. 2008 ) This is why the area surrounding a WUI is important in development and why home values might be higher in these areas. 1.4 Subsequent Chapters The following chapters of this thesis examine the steps taken to conduct an REA and the subsequent results. In the Methods section, an exploration of the study site is reviewed, foll owed by techniques used to gather the data. Additionally, the Methods give an understanding of why specific parameters are chosen to be evaluated, as well as a review of the statistical tests conducted. A very detailed Analysis of Results follows, outlinin g and examining specific parameters in the context of data collected along at each study site. Also included in this section are an image of each site location alongside any related specific findings and highlighting any anomalous trends, as well as an ove rview

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6 of home values along each site. The last chapter, Discussion and Recommendations elaborates on parts of the Analysis and Results including a detailed discussion of the statistical testing results and pertinence of home values to the study, with a special section addressing societal applications. Finally, recommendations and future work are discussed.

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7 2 Introduction to Metho ds development on local ecosystems, primary in sensitive riparian areas along the Hig h Line Canal Trail, comprising 66 miles (about 106 kilometers) of trail through Douglas, Arapah oe, and Denve r Counties in Colorado (Figure 2.1 ) ( Water 2011 ) Figure 2. 1 : A map showing all 71 miles of the High Line Canal Trail, broken up into two sections: Lower (Eastern) and Upper (Western) Canal ( Bielenberg 2008 ) The numbers on the map correspond to the location of each site studied.

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8 This site was chosen because of its high pedestrian traffic through an urban center, which can severely damage local ecology ( Bhuju and Ohsawa 1998 ) and its close proximity to a naturalized riparian area. The dry summer climate in Colorado, along with the trail being on an urban fringe, can result in the soil and vegetation being sensitive to disturbance. The data was collected on 10 separate days be tween August and October 2013. This ensured full vegetation coverage (if applicable) with little weather interference. Though the High Line Canal is human built, it has been naturalized into the local ecosystem over a span of 130 years, and is home to a va riety of riparian biota ( Water 2011 ) This study closely follows the parameters for a Rapid Ecological Assessment (REA) ( Vanderho rst, Program. et al. 1993 Preskitt, Vroom et al. 2004 Allen 2009 McHugh and Thompson 2011 Kotze, Ellery et al. 2012 Medeiros and Torezan (2013) ) where only necessary and subjective data are collected pertaining to soil and vegetation disturbance. Though there are several critics of REA and it should not be a replacement for long term field work, it is an efficient and quick way to assess the quality of a site ( Abate 1992 ) 2.1 Study S ite The High Line Canal Trail begins southwest of Denver, Colorado, close to Chatfield Reservoir. The H igh Line Canal Trail runs through a Wildland Urban Interface ( Theobald and Romme 2007 ) Between August and October, the average temperature during the day ranges between 65 to 87 Fahrenheit with only about four inches of rain, resulting in very dr y s oils ( Denver ) Along the Front Range, soils are primarily heavy clays that ca n prevent water absorption and make it difficult for vegetation to grow.

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9 Mineral salts and high pH (more basic) levels are other characteristics of soil in the Denver area, and these too play a role in soil fertility ( Pohly 2010 ) As the High Line Canal Trail zigzags 71 miles (66 usable miles) through the area, its entire length was not surveyed. Instead, ten equally spaced one kilometer sites were used as a proxy for the trail, allowing for representation of the entire trail l ength without any bias. Starting with kilometer three, each site is ten more kilometers than the previous site (Table 2.1 ). Table 2. 1 Location of the study areas along the High Line Canal Trail. *Trail discontinues at 8.6 miles and starts back up at mile marker 9.6. Site km marker (Mile Marker) 1 3 4 1.9 2.5 2 13 14 8.1 8.7* 3 23 24 14.3 14.9 4 33 34 20.5 21.1 5 43 44 26.7 27.3 6 53 54 32.9 33.5 7 63 64 39.1 39.7 8 73 74 45.4 46.0 9 83 84 51.6 52.1 10 93 94 57.8 58.4

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10 At each one kilometer site, and based on a previous stratified random sample method described by Allen (2009), Medeiros and Tore zan (2013) and Preskitt, Vroom et al. (2004), numbers between one and four were randomly drawn to determine the length of time, in minutes, to walk before taking measurements, providing a stratified random sample of the study area. Each stop along the one kilometer segment was considered a Mede iros and Torezan (2013) and Allen (2009). Several transects were described and measured in each one kilometer site depending on the number drawn. For example, Site 1, between mile markers 1.9 and 2.5 (three and four kilometers), had four transects, whil e Site 3, between mile markers 14.3 and 14.9 (23 and 24 kilometers) had six transects. This depends entirely on the random process of pulling a number blindly out of a bag and walking that designated length of time (in minutes) at each site until the full kilometer of the representative section has been walked. At each transect, the canal and non canal sides of the trail were surveyed. Generally, the canal side of the trail is to the right of the trail when increasing in mile marker numbers. The non canal s ide of the trail is generally the left side. 2.2 Data Gathering The measurements on either side of the transect were obtained using a standard 25 foot tape measure. At each transect, parameters where measured at a half meter, one meter, one and a incremental data (Figure 2.2 ).

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11 Figure 2 .2 Each parameter was assessed using a range of percentages ( Table 2.2 ). This breakdown of percentages is similar to the Index of Biotic Integrity (IBI) classes, though the corresponding percentages are more applicable to general and multi use recreational trail REAs ( Preskitt Vroom et al. 2004 Allen 2009 McHugh and Thompson 2011 Kotze, Ellery et al. 2012 Medeiros and Torezan 2013 ) Table 2 .2. Approximation of how each parameter is measured. NA indicates Not Applicable and can refer to a) No vegetation present or b) The location cannot be measured. A location cannot be measured if it is blocked by fence, or there is a steep cates there is no alteration to the parameter being measured. As an Value given Corresponding impact percentages NA Not Applicable 0 None present 1 1 25% 2 26 50% 3 51 75% 4 76 100% Legend: away from trail edge Blue represents 1.5 2 meters Orange represents 1 1.5 meters Red represents 0.5 1 meter Green represents 0 0.5 meters

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12 Each percentage range indicates each parameter in a specific transect on either side of the there is 26 50% disturbed soil on the non canal side of the trail betwee n 0 and 0.5 meters Table 2. 3 provides a visual representation of each measurement. Table 2. 3 Visual representation of indicator values based on the parameter of vegetation density. 0 indicator for vegetation density (no vegetation present) 1 indicator value for vegetation density (1 25%)

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13 Table 2.3 (con t) 2 indicator value for vegetation density (26 50%) 3 indicator value for vegetation density (51 75%) 4 indicator value for vegetation density (76 100%)

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14 2.3 Parameters follow other established REAs ( Vanderhorst, Program. et al. 1993 Allen 2009 Medeiros and Torezan 2013 ) These parameters include: Soil D isruption Disturbed Vegetation Presence of Bare Ground Tree/ Woody Vegetation Density Grass/ Herbaceous Vegetation Density Overall Disturbance In some areas, a dominant plant species is also identified. The importance of identifying dominant plants in each transect can assist in providing management techniques. The presence of non native and invasive species can quickly degrade the quality of the ecology around the trail ( Barbier, Knowler et al. 2013 ) A species is only collected for identification if prominent floral characteristics are present. Choosing plants that can be easily identified compliments the rapid ecological assessment at the study site by only examining key impacts to the High Line Canal Trail ( Vanderh orst, Program. et al. 1993 ) Each of these parameters are measured at each transect on the canal side of the trail (right side increasing in mile markers) and non canal side at the pre determined distances away from the trail ( Table 2.3 ).

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15 Table 2. 4 M atrix of each parameter along each transect for both sides of the High Line Canal Trail. Note that a dominant species was not identified at each transect. Time Multiplier (_____m) 0 .5 m 0.5 1 m 1 1.5m 1.5 2m Disturbed soil Left Right Disturbed vegetation Left Right Bare Ground Left Right Tree/ Woody density Left Right Grass density Left Right Disturbance (Y/N) Left Right Dominant Species Left Right

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16 2.4 Testing To get a clear idea of any spatial trends, variations, and/or anomalies along the non canal side were averaged separately to identify any separate trends that might be present. Once averaged, a linear regression model was applied to determine any trends in the data. A paired t test is used for each parameter throughout the entire study area to calculate any significance in the data between the canal side and non canal side of the trail. In this particular case, a paired t test represents a strong method to detect differences on either side of the High Line Canal Trail. A p value is calc ulated, accepting or rejecting the null hypothesis of H o : P c = P nc canal side of the trail. While the experimental hypothesis is H o : P c P nc The results will be significant if the resulting p value is below the significance level of 0.05. The resultant value aids in determining if the parameters exhibit any statistical significance. corresponding trail location. This is to determine if higher home values correlate with a

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17 less natural, highly disturbed sections of the High Line Canal Trail. American Trails, a non profit organization, has shown that having walking areas close to neighborhoods increases home values $4,000 to $34,000 compared to homes that do not offer such walkability ( Cortright 2009 ) The average home values along each study site are d etermined by the website Trulia. As this study assesses trail impact at a popular, rapidly expanding Wildland Urban Interface area in De nver, CO, gaining insights into property values associated with it could influence future policies associated with land use, development, and recreational opportunities.

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18 3 Analysis of Results The Rapid Ecological Assessment (REA) along the High Line Canal Trail resulted in several noticeable and non noticeable conclusions. Six parameters were measured, but only four provided enough information to extrapolate important characteristics of the tra il. Tree/Woody density parameter resulted in little findings. Their presence was found along the study area with leaf litter and shade, but could rarely be indicated as a part of the assessment because the trunk or stem of the species was located more than two kilometers away from the trail (outside the study area). Additionally, overall disturbance parameter resulted in almost all transects at each site having some kind of prominent disturbance. The main disturbance was grass cutting and pruning. The rem aining four parameters, disturbed soil, disturbed vegetation, bare ground, and vegetation density, provided varying results throughout the study area. At each site, transects were averaged (the canal and non canal side separately) for the specific paramete r in question. The number of transects were randomly decided by picking a number out of a hat and walking that distance in minutes until the full kilometer was surveyed (Table 3.1). Figures 3.1 3.4 show the averaged values for each parameter at all 10 site s for both canal and non canal sides of the trail. A linear regression line was added to indicate any trends. The y axis is valued 0 4, which is the range of percentages being measured ( Table 2.2 ). First, the parameters (disturbed soil, disturbed vegetat ion, bare ground, and vegetation density) will be examined. The site transects are averaged to obtain an overview of the parameters at each site. The canal and non canal side are calculated

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19 separately to show any variation within a single site. A linear re gression line is added to observe general trends of each parameter along the High Line Canal Trail. Next, a review of statistical analysis is discussed. A paired t test is conducted on the four parameters comparing the canal and non canal side of the trai l. The statistical testin g is significant if any prominent variability between the canal and non canal side of the trail at each site is found After a review of the parameters, each site is analyzed separately in conjunction with its physical location a long the trail. A satellite image is provided to get a clear indication of factors that might influence the data collected and overall quality. Each site is summarized by all six original parameters that include tree/woody density and overall disturbance. The indicator values are discussed in reference to the parameters with a comparison of the canal and non canal side of the trail at each site. Finally, a comparison of home values along the High Line Canal Trail study sites is discussed with t he average home price compared to the overall trends at each site for the four main parameters. This will show if home values play a direct role in the quality of the ecology surrounding the High Line Canal Trail. The earlier hypothesis suggests that with higher hom e values, the study sites along the trail will have more disruption. A review for each analysis section will be discussed in the Discussion of Results following these analyses 3.1 Number of Transects at each Site Location The number of transects at eac h site location was determined by randomly picking a number out of a hat that represents the length in minutes to walk to the next transect

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20 location. This ensures that random data was collected to provide an accurate representation of the trail. Each site had between four and six transects at the site (which is one kilometer long). Table 3.1. Number of transects at each site. This is determined by randomly being a number out of a hat as a value for the number of minutes to walk between each transect until one kilometer was studied. Site location Number of Transects 1 4 2 4 3 5 4 5 5 6 6 6 7 6 8 5 9 5 10 5

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21 3.1.1 Disturbed Soil The disturbed soil parameter measured any likely anthropogenic soil disruption. The most disturbance of soil occurred 0 to 0.5 meters away from the trail. The linear regression line shows that as the mile markers increase along the trail, the presence of d isturbed soil increased on the canal side of the trail. There are very drastic differences in the indicator values between canal side and non canal side of the trail in the same site. The most apparent is site 7, which is between kilometers 63 and 73 on th e High Line Canal Trail. The non canal side of the trail has a value of 0.208, while the canal side has an average value of 2.13. This means that on the non canal side there could be only 15% overall soil disturbance, while the canal side could have as hig h as over 50% soil disturbance. Figure 3. 1 Average indicator values at each site for Disturbed Soil on the canal and non canal sides of the High Line Canal Trail. The green markers indicate a location where the canal side and non canal side of the trail have the same values. 0 0.5 1 1.5 2 2.5 1 2 3 4 5 6 7 8 9 10 Indicator Site Disturbed Soil Non-Canal Canal Linear (Non-Canal ) Linear (Canal)

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22 At sites 8 and 10, the values for soil disturbance are very similar with 0.85 and 0.9, respectively. Sites 3 and 6 both have values of 0 for soil disturbance, indicating that no soil disturbance was found on the respective sides of the trail. Overall, the canal side had a higher rate of soil disturbance than the non canal side of the trail based on the linear regression model. The non canal side remained relatively flat in the increase of soil disturbance, while the regress ion line for the canal side shows a dramatic increase of soil disturbance as the mile markers increase. A review of these results will be discussed in 3.1.2 Disturbed Vegetation Figure 3 .2 A verage indicator values at each site for Disturbed Vegetation on the canal and non canal sides of the High Line Canal Trail. The green markers indicate a location where the canal side and non canal side of the trail have the same values. The disturbed vegetation parameter displays very high values at each site along the High Line Canal Trail. The lowest value is at site 1 on the non canal side of the trail, with just over 2. This represents a value between 26 and 50% of the vegetation at t hat site 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 1 2 3 4 5 6 7 8 9 10 Indicator Site Disturbed Vegetation Non-Canal Canal Linear (Non-Canal) Linear (Canal)

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23 on the non canal side of the trail has disturbed vegetation. The highest values of disturbed vegetation are shown between sites 4 and 8 (between kilometer 33 and 74 on the trail). Four sites have indicator values of 4 (Site 4 non canal side, Sit e 6 canal side, Site 7 canal and non canal side), which represents 76 100% disturbance. The first two sites and last two sites of the study have the overall lowest values of vegetation disturbance. The linear regression lines exhibit an interesting t rend for the canal and non canal side of the trail. Until site 6, the canal side had a greater value than the non canal side for disturbed vegetation. After site 6, the non canal side had a greater value. This is likely due to the large discrepancy between the canal side and non canal side indicators at site 9. Site 9 has an indicator value of 2.5 for the canal side, while the non canal side has a value of 4. There is a pretty steady increasing trend of disturbed vegetation on the non canal side of the tra il, while the canal side trend remains relatively flat.

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24 3.1.3 Bare Ground Figure 3. 3 Average indicator values at each site for Bare Ground on the canal and non canal sides of the High Line Canal Trail. The green markers indicate a location where the canal side and non canal side of the trail have the same values. Bare ground represents an area where no vegetation is present, but there is also no sign of disturbance. Bare ground differed between non canal and canal side of the trail conside rably. Only at site 8, where the values were the same (1.75), did either side of the trail have similar values. The largest area of discrepancy is at site 7, where the canal side of the trail has an indicator value of about 3, but the non canal side has an indicator value less than 1. Site 8 has the same value for both the canal side and non canal side of the trail with 1.75 as well, meaning most of the site has between 30 45% bare ground. Finally, site 10 shows the lowest amount of bare ground present at a ny of the study sites for both sides of the trail. There was no site that had over an indicator value of 3, meaning there was no site that averaged over 50% of bare ground. 0 0.5 1 1.5 2 2.5 3 3.5 1 2 3 4 5 6 7 8 9 10 Indicator Site Bare Ground Non-Canal Canal Linear (Non-Canal) Linear (Canal)

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25 The linear regression line for sides of the trail decrease as the mile markers alo ng the trail increase. Both lines begin very close to one another, but the non canal side regression line decreases much more rapidly than the canal side of the trail. The steep decrease in the regression line represents lower indicator values for bare gro und and is likely the result of small values on the non canal side at sites 7, 9, and 10. 3.1.4 Vegetation Density Figure 3. 4 Average indicator values at each site for Vegetation Density on the canal and non canal sides of the High Line Canal Trail. Vegetation density demonstrates how much vegetation was present along the trail at each site. Vegetation found along the High Line Canal Trail is primarly grasses. Though herbaceous weeds and occasionally shrubs are also prese nt, unquestionablly Poaceae (Grass family) is the dominant vegetation. Site 7 has very low vegetation 0 0.5 1 1.5 2 2.5 3 3.5 4 1 2 3 4 5 6 7 8 9 10 Indicator Site Vegetation Density Non-Canal Canal Linear (Non-Canal) Linear (Canal)

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26 density of the canal side, this complements the bare ground parameter that shows very high bare ground on the canal side of the trail. Similar results ar e shown with the non canal side, too. On average, the canal side of the trail has lower vegetation density then the non canal side. A linear regression trend of increasing vegetation density is observed for the canal and non canal sides of the trail. Eac h regression line began close to one another around the second indicator (26 50%). Yet, the non canal regression line increased more rapidly than the canal line. The canal side stayed under 2.5, while the non canal side rose above 3 (a 25% increase in vege tation cover). 3.2 Statistical Testing A paired t test was conducted for each parameter comparing the canal and non canal side of the trail at all 10 site locations along the High Line Canal Trail. Each test provided no statistically significant results. This concludes the evidence that there is insufficient data to reject the null hypothesis ( H o : P c = P nc ) as mentioned in the Methods section of this paper. It is unlikely that the canal side and non canal side of the trail differ significantly 3. 3 Site L ocations Each of the 10 site locations are shown below. The aerial map provides insight as to the quality and terrain surrounding the High Line Canal Trail. The green dash marks on the map show the exact location of the site studied. Each green marker is

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27 approximat ely one kilometer long, the length of each site. As a reminder, the canal side of the trail is to the right and the non canal side is to the left for perspective. 3.3.1 Site 1 Figure 3. 5 Site 1 of the High Line Canal Trail located kilometers 3 4. The green dashed line represents the location of the Trail study area. Site 1 is located between 3 and 4 kilometers on the High Line Canal Trail (mile marker 1.9 2.5). There were a total of four transects that were studied at thi s location. Varying results were seen between each transect. The second transect was the only one that had very high disturbed soil (an indicator of 4). All other transects at this site only had an indicator of 1 for disturbed soil. There was only one wood y plant observed at this site. It was located in the third transect, 1.5 meters away from the trail on the non canal side. The second transect, on the canal side of the trail, had very little vegetation present.

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28 Overall, Site 1 had minimal anthropogenic im pact, particularly compared to the other study sites. 3.3.2 Site 2 Figure 3. 6 Site 2 of the High Line Canal Trail located kilometers 13 14. The green dashed line represents the location of the Trail study area. Site 2 is located between kilometer 13 and 14 on the trail (mile marker 8.1 8.7). The survey of this site was reduced by one tenth of a mile because the trail briefly discontinued at mile marker 8.6. Site 2 also had four transects. The only tree/woody spec ies present was located in the third transect, one meter away from the trail on the canal side. Most transects had some kind of disturbed vegetation, primarily from mowing, except for the canal side of the second transect that had no vegetation disturbance

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29 3.3.3 Site 3 Figure 3. 7 Site 3 of the High Line Canal Trail located kilometers 23 24. The green dashed line represents the location of the Trail study area. Site 3 is located at kilometers 23 33 on the Trail (mile marker 14.3 14.9). There were five transects studied along this site. For most of the site, there was a slope coming down to the trail on the non canal side and a slope going from the trail to the canal on the other side. This varying terrain impacted the paramet ers observed. Similar to the last sites, site 3 only has one documented tree/woody vegetation species At the third transect on the non canal side, there is no vegetation present and all the soil has been disturbed, mainly due to much mowed grass.

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30 3.3.4 Site 4 Figure 3. 8 Site 4 of the High Line Canal Trail located kilometers 33 34. The green dashed line represents the location of the Trail study area. Site 4 is located at kilometer 33 34 (mile marker 20.5 21.1) on the High Line Canal Trail. This site had five transects documented. For most of the site, very little disturbed soil was documented. Vegetation disturbance, on the other hand, was extremely high, with each transect averaging an indicator of four, yet no tree/woody species was document along this segment of the trail. There were variations in bare ground and thus variations in vegetation density, ranging from zero to an indicator of four. The third transect of the site was very close to a road and likely influenced t he parameters with almost 100% disturbed vegetation. The last transect had documentation of tire tracts along the trail, likely for maintenance including mowing along the trail.

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31 3.3.5 Site 5 Figure 3. 9 Site 5 of the High Line Canal Trail located kilometers 43 44. The green dashed line represents the location of the Trail study area. Site 5 is located between kilometers 43 44 (mile marker 26.7 27.3), and six transects were studied. Each transect, except for the fourth, had hi gh levels of disturbed soil on the canal side of the trail. The non canal side had very little soil disturbance, likely because it was on a slope for most of the site. Again, there were no tree/woody species documented throughout the site. Also, similar to the previous sites, this site exhibited an average of 76 100% disturbed vegetation. Overall, the vegetation density was much higher on the non canal side of the trail then the canal side.

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32 3.3.6 Site 6 Figure 3. 10 Site 6 of the High Line Canal Trail located kilometers 53 54. The green dashed line represents the location of the Trail study area. Comprised of six transects, site 6 is located between kilometers 53 54 (mile markers 32.9 33.5). Throughout all transects, no tree /woody vegetation was documented. The second and fourth transects could only be measured one meter away from the trail on the canal side because of a steep slope leading into the canal. Each transect had very high indicators of vegetation density, likely r esulting in the low indicators for disturbed soil and bare ground. Overall, site 6 had high human impact and experienced high disturbances.

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33 3.3.7 Site 7 Figure 3. 11 Site 7 of the High Line Canal Trail located kilometers 63 64. The green dashed line represents the location of the Trail study area. Site 7 is located between kilometers 63 64 (mile markers 32.9 33.5) and contains six transects. Populus deltoides (Cottonwood) was identified in the fourth transect two meters away on the canal side of the trail. The study site had extreme differences between the canal side and non canal side of the trail. The canal side has very high indicators for bare ground, while the non canal side had very few areas with bare ground. This is because of a dirt path that ran parallel to the trail on the canal side. Tire tracks were noticeable and the path was likely for maintenance vehicles. A large anthropogenic presence was obser ved at this site, more so than any other study site along the High Line Canal Trail, but the disturbance was primarily from the mowing of vegetation along the trail.

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34 3.3.8 Site 8 Figure 3. 12 Site 8 of the High Line Canal Trail located kilometers 73 74. The green dashed line represents the location of the Trail study area. Site 8 is located between kilometers 73 74 (mile markers 45.4 46.0) on the High Line Canal Trail, and comprises five transects. Though there were no tree/woody species present along the two meter parameter of the trail in site 8, a large cottonwood was ove rhanging the canal side trail segment of the fourth transect. This could have contributed to lower vegetation density and higher bare ground in this transect because vegetation could be covered with leaf litter, making it difficult to grow. Poaceae dominat ed vegetation at this site, except at the fifth transect where Tribulus terrestris (Goat head thorn) was found at very high amounts. This is an incredibly invasive weed producing seeds that can puncture bike tires. Overall, Site 8 had high anthropogenic di sturbance.

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35 3.3.9 Site 9 Figure 3.13. Site 9 of the High Line Canal Trail located kilometers 83 84. The green dashed line represents the location of the Trail study area. Consisting of five transects, site 9 is located at kilometers 83 84 (mile markers 51.6 52.1) on the High Line Canal Trail. No tree/woody species was documented at this site. At this site, the trail split into two sections, an upper dirt path and a lower paved path at transects three, four, and five. The data collected was only from the paved part of the trail and there is no documentation of the parameters on the unpaved path. Also at the third transect, a fence located on the non canal side of the trail blocked the ability to collect data between 1.5 and two meters. There was very little disturbed soil documented along the entire site, only at transects one and four on the canal side of the trail were there high indicators of soil disturbance. Overall site 9 showed high levels of huma n disturbance.

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36 3.3.10 Site 10 Figure 13 Site 10 of the High Line Canal Trail located kilometers 93 94. The green dashed line represents the location of the Trail study area. Site 10 is located at kilometers 93 94 (mile markers 57.8 58.4) along the High Line Canal Trail, and contained five transects. Again, there is no documentation of tree/woody species located along the trail. At transect one, there was Pinus ponderosa (Ponde rosa Pine) needles along the non canal side of the trail, but this did not impact the vegetation density of the transect. There was very high vegetation densities found throughout the trail, except for transect two, which had no vegetation on either side o f the trail until 1.5 meters. At transect three, as with site 9, the trail split into an unpaved and paved section, but data was only collected on the paved portion. Overall, there was significant anthropogenic disturbance along the trail. At each transect concrete pieces were found along the trails edge.

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37 3.4 Home V alues Average home values for each site was calculated to determine if an area with high home value has higher instances of trail disturbance along the Hig h Line Canal Trail and is noted in Table 3.2 The site with the highest home value is site 6, located in Cherry Hills Village with the average home cost along the canal being $3,300,000. Site 6 has high average rates of bare ground and disturbed soil, but has one of the lowest overall indi cators for disturbed soil on the canal and non canal side of the trail. Located in Denver County, site 7, with the third lowest average home values at $369,000, shows the highest indicator of overall disturbance in each parameter. Based off of a simple com parison between home value prices along the canal and parameter values, there is likely no correlation between home value price and trail disturbance. Table 3.2. Average home values at each site along the High Line Canal Trail. Site Average Home value ($) Location 1 400,000 Douglas County 2 426,000 Douglas County 3 600,000 Highlands Ranch 4 349,000 Littleton 5 1,088,000 Greenwood Village 6 3,300,000 Cherry Hills Village 7 369,000 Denver County 8 370,000 Arapahoe County 9 124,000 Aurora Hills Golf Course 10 158,000 Laredo Highline

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38 4 Discussion and Recommendations Analyzing background information and methods used to create and implement a Rapid Ecological Assessment (REA) along the Wildland Urban Interface (WUI), this chapter discusses results pertaining to societal applications, and offers recommendations for this research project and suggests directions for future studies. To accomplish these goals, this chapter begins with a discussion of the analysis that iden tifies overall trends in the data (parameters, statistical testing, and home values) while also offering potential explanations of factors that could have contributed to the results. Then, societal applications of the REA in relation to how the research te chniques employed in this study can be applied to other urban trails is offered. Finally, the chapter ends with an in depth summary outlining possible shortcomings, as well as future opportunities and their implications. 4.1 Discussion of Analysis This s several parameters. First, the four parameters are examined and extrapolations of the data will be made to discern any potential reasons for trail quality. Next, a review of statis tical analysis is offered to help identify if the canal and non canal sides of the trail significantly differ for each parameter. Additionally, this underscores potential reasons for indicator values at site locations. That is, it will provide a speculatio n as to why various parameters have specific indicator values. Finally, an evaluation of home values in reference to site locations along the High Line Canal Trail is reviewed. This is important to the study because it identifies if there are economic fact ors that contribute to

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39 trail disturbance. Each section also provides an appropriate conclusion in regards to anthropogenic impacts on the High Line Canal Trail. 4.1.1 Parameters There were four primary parameters that were assessed along the High Line Canal Trail: Bare Ground, Disturbed Vegetation, Vegetation Density, and Disturbed Soil. Each parameter resulted in varying conclusions about the overall quality of the High Line Canal Trail at each site. Sites that have high indicator values for a paramet er will be evaluated. First, Disturbed Soil had overall low indicator values. This is likely because the High Line Canal Trail was either paved (majority of the trail) or was gravel. Through on the ground data collection and observations, it was noticed that there was minimal direct human impact off the paved or graveled trail. Based on visual evidence as recorded in the REA matrices, the likely reason for any disturbance is because of pets and maintenance for the trails. Many dogs have the freedom by their owners to walk off the path both on or off a leash ( Reynolds, Wolch et al. 2007 ) Additionally, maintenance trucks easily disturb soil. This is the case at site 7 along the canal side of the trail, where visible tire tracks can be seen while performing the Rapid Ecological Assessment (Figure 4.1 ).

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40 Figure 14 Image of tire marks taken at Site 7. Second, the Disturbed Vegetation parameter exhibited high indicators at each site surveyed. As noted in the REA matrices, this is likely due to on the trail maintenance. The vegetation had clearly been mowed, particularly when a street or activity area/park was close to the trail. This is the case with the non canal side at Site 9, which borders a large fenced in green space. At Site 7, an indicator value of 4 for both the canal and non canal side of the trail was likely due to the proximity of the trail to Interstate 25. Safety is a primary factor of mowing vegetation, because of potential harmful interactions with wildlife and humans. In general, disturbed vegetation rates were high on both canal and non canal sides of the trail, and typically, closer to the canal had lower vegetation disturbance. As a reminder, the study area was two meters on either side of the trail. Additionally, the low rates of disturbed vegetation at site 1 and 10 are likely because ther e is not much development in the area resulting in a smaller maintenance presence.

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41 Third, some anomalous readings were present when assessing Bare Ground. As mentioned previously, Site 1 had very little vegetation, which is why the indicator values are h igh for Bare Ground at that site. Also, there are large discrepancies at Site 7 and 9 between the canal and non canal sides of the trail, but this is primarily because of the presence of maintenance vehicle tracks, with visible tire marks seen at both loca tions (Figure 14) Finally, Vegetation Density fluctuates a great deal between canal and non canal sides of the trail. As with past parameters, presence of maintenance vehicles and proximity to streets can all be influential to vegetation density. A gene ral increase in vegetation density along the High Line Canal Trail is likely due to closer proximity to humans, which can result in more vegetation to be planted along the trail. This increase in vegetation density is likely just for aesthetic appeal. 4.1 .2 Statistical Testing The results of the paired t test on the four parameters concluded there was no statistically significant difference between the canal and non canal sides of the trail. For each parameter, there was insufficient data to reject the nu ll hypothesis of the canal side and non canal sides of the trail to be equal. These results demonstrate that even though some fluctuations between the canal and non canal sides of the trail for each parameter were discovered, there were no significant disp arities between the sides of the High Line Canal Trail. This is likely due to the small perimeter around the trail that was tested (two meters on either side). Judging from field based observations, if data were collected up to five meters on either side o f the trail, there would potentially be more discrepancies

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42 between the two sides, and perhaps even a statistically significant trend that could help predict impact of trail use at the WUI. 4.1.3 Home Values The average home values along each site at the H igh Line Canal Trail assist in identifying any impacts to the trail based on economic values. Once analysis of site locations and home prices were compared, it seems that little correlation is present ( Table 3.2 ). It is likely that the trail is more impacted by proximity to streets and high human traffic than wealth of an area as found in other studies ( Marion and Leung 2001 Alavalapati, Carter et al. 2005 Allen 2009 Cortright 2009 McHugh and Thompson 2011 Buonopane, Snider et al. 2013 ) Even in sites with very high home values, trail parame ters did not differ considerably from sites with low home values, and, as with other parameters, the largest discrepancies occurred in areas with a high volume of human and vehicle traffic and varying vegetation growth. 4.2 Societal Applications It is important to note the necessary balance that must be present between humans and the ecosystem, particularly on trails through WUI areas. These areas are susceptible to high amounts of pollution (trash), contaminants (pet feces), invasive plant specie s (escaped horticults), and overall disturbance (human presence) ( EPA 2013 ) There is a severe lack of policy regarding trail development, particularly trails that run through WUIs. The desire to have more outdoor opportunities has overshadowed potential issues to the ecosystem due to development ( Bhuju and Ohsawa 1998 Marion

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43 and Leung 2001 ) More policy should be enacted to allow regulations in trail development ( McHugh and Thompson 2011 Denver 2012 ) Based on the findings of Bhuju and Ohsawa ( 1998 ) and Kotze, Ellery et al. ( 2012 ) findings, REAs can be beneficial in helping establish environmentally friendly multi use trails. It is a quick and efficient way to provide an overall quality assessment of the area ( Vanderhorst, Program. et al. 1993 Preskitt, Vroom et al. 2004 Kotze, Ellery et al. 201 2 Medeiros and Torezan 2013 ) Regardless of the location of a trail (urban, rural, etc.), natural ecosystems will be impacted because of the increase presence of anthropogenic factors. Trails that run wildland interface ( Bhuju and Ohsawa 1998 Marion and Leung 2001 Wimberly, Zhang et al. 2006 Theobald and Romme 2007 Buonopane, Snider et al. 2013 ) Additionally, monitoring and unified management techniques of the trail are necessary to maintain ecological health ( Marion and Leung 2001 McHugh and Thompson 20 11 ) The High Line Canal is managed only by Denver Water, but the trail is managed by d ifferent communities in which it passes. According to Denv er Water (2014), there are seven agencies that oversee the High Line Canal Trail. Various management techniques exist between the different agencies, when one comprehensive organization should maintain the quality of the High Line Canal Trail. Public outr each and education is one way to promote a more environmentally conscious individual ( Martin, Sorice et al. 2013 ) Educational programs and outreach that incorporate local organizations and home owners along the trail can provide increase support for trail management and upkeep, including education about invasive and non native plant spe cies and its impacts

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44 accessible to communities members and policy makers ( Schiller, Hunsaker et al. 2001 Allen 2009 ) 4.3 Future Work and Recommendations This rapid ecological assessment conducted on the High Line Canal Trail serves as a brief synopsis of the overall quality of the trail. Due to time and financial limitations, there are several aspects of this project that can be explored by future researchers. Although REAs should not be a replacement for long term field studies, they are effective tool that can provide broad conclusions about an area (Ab ate 1992). For this reason, a n REA was designed for this project, and highlights the importance of REAs for management purposes along with its ease of use. Limited data was collected in a short period of time to provide a general assessment of the trail, but more in depth research could be collected and provide more detailed data that possibly could lead to better explanations and specific trends. REAs could be implemented to other urban trails around the County to provide a basis for trail quality in are as of high anthropogenic impacts. For example, Denver has five major trails, Cherry Creek, Bear Creek, High Line Canal, South Platte River, and Sand Creek Trail. REAs could be conducted on each trail ng potential management techniques for cities that have high disturbance values. In terms of overall investigation, several factors were discovered that could have hindered the extent of analysis. First, the restricted size of the canal and non canal sid e measurement areas was limited. Only two meters on either side were measured, but in the future, it would be more beneficial to obtain data as much as five meters on either side of

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45 the trail. This would potentially strengthen the similarities or differenc es found in the data between each the canal and non canal sides of the trail Second, the entire trail length could be analyzed, breaking the sites into single kilometer segments or by designated neighborhood/green space/park space. Of course this would re quire much more time, but could still be efficiently done using a n REA. Overall, the data collected along the High Line Canal Trail provides an insight to the issues surrounding a trail that runs through a WUI. Using a n REA provided a quick and straight f orward survey of parameters often used to indicate trail impacts (bare ground, disturbed soil, disturbed vegetation, and vegetation density). The study followed previously established REA guidelines ( Abate 1992 Preskitt, Vroom et al. 2004 Allen 2009 McHugh and Thompson 2011 Kotze, Ellery et al. 2012 ) but it is the first of its kind to study a trail that has very heavy anthropogenic impacts and runs through a WUI. Future researchers can use this study as a base from whic h to draw upon when assessing other WUI areas, and gain a general overview of potential trail impact, and these findings could influence future management plans. In the end, this study highlight ing main impacts of trail development th rough a WUI using the straightforward technique of a Rapid Ecological Assessment that can be performed with limited time and budget to gain insight to potential ecological disturbances The REA parameters mentioned in this study can be a basis for other wo rld wide studies to replicate potential anthropogenic impacts on an urban trail and identify if there are economic ties to ecological health.

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46 REFERENCES Abate, T. (1992). "Environmental Rapid Assessment Programs Have Appeal and Critics." BioScience 42 (7): 486 489. Agriculture, U. S. D. o. (2004). Conservation Corridor Planning at the Landscape Level Managaing for Wildlife Habitat. Subpart B Part 613. N. R. C. Service. Alavalapati, J. R. R., et al. (2005). "Wildland urban interface: Challenges and opportunities." Forest Policy and Economics 7 (5): 705 708. Allen, C. D. (2009). "Monitoring environmental impact in the upper Sonoran lifestyle: a new tool f or rapid ecological assessment." Environmental management 43 (2): 346 356. Alston, K. P. and D. M. Richardson (2006). "The roles of habitat features, disturbance, and distance from putative source populations in structuring alien plant invasions at the ur ban/wildland interface on the Cape Peninsula, South Africa." Biological Conservation 132 (2): 183 198. Amati, M. and M. Yokohari (2006). "Temporal changes and local variations in the functions of London's green belt." Landscape and Urban Planning 75 (1): 125 142. Barbier, E. B., et al. (2013). "Implementing policies to control invasive plant species." BioScience 63 (2): 132 138. Bhuju, D. R. and M. Ohsawa (1998). "Effects of nature trails on ground vegetation and understory colonization of a patchy remnant forest in an urban domain." Biological Conservation 85 (1 2): 123 135. Bielenberg, R. a. J. (2008). "To Be Treasured and Enjo yed Denver's High Line Canal!". from http://actvra.in/4c26#sthash.BvcgA6NE.dpu Buonopane, M., et al. (2013). "Complex restoration challenges: Weeds, seeds, and roads in a forested Wildland Urban Interface." Forest Ecology and Management 295 (0): 87 96. CBS (2011). Broomfield Dad describes Coyote Attack On His Son. CBS, Denver Denver, Colorado.

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49 Sayre, R. (2000). Nature in focus: rapid ecological assessment Island Press. Schiller, A., et al. (2001). "Communicating ecological indicators to decision makers and the public." Conservation Ecology 5 (1): 19. So ule, M. E. (1991). "Land use planning and wildlife maintenance: guidelines for conserving wildlife in an urban landscape." Journal of the American Planning Association 57 (3): 313 323. Stella, J., et al. (2013). "Riparian vegetation research in Mediterran ean climate regions: common patterns, ecological processes, and considerations for management." Hydrobiologia 719 (1): 291 315. Sutula, M. A., et al. (2006). A PRACTICAL GUIDE FOR THE DEVELOPMENT OF A WETLAND ASSESSMENT METHOD: THE CALIFORNIA EXPERIENCE1, Wiley Online Library. Theobald, D. M. and W. H. Romme (2007). "Expansion of the US wildland urban interface." Landscape and Urban Planning 83 (4): 340 354. Trombulak, S. C. and C. A. Frissell (2000). "Review of ecological effects of roads on terrestria l and aquatic communities." Conservation Biology 14 (1): 18 30. Tyser, R. W. and C. A. Worley (1992). "Alien flora in grasslands adjacent to road and trail corridors in Glacier National Park, Montana (USA)." Conservation Biology 6 (2): 253 262. Universit y, C. S. (2013). "Colorado noxious weeds." 2014, from http://www.ext.colostate.edu/ptlk/2103.html Vanderhorst, J. P., et al. (1993). Rapid ecological assessment of selected state lands in south central Montana for plant species of special concern / prepared by James P. Vanderhorst ; prepared for Montana Department of Fish, Wildlife and Parks Helena, MT :, Montana Natural Heritage Program. Vince, S. W., et al. (2004). Forests at the wildland ur ban interface: conservation and management CRC Press.

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50 Water, D. (2011). Guide to the High Line Canal Trail. Denver Water Community Relations Office D. Water. Water, D. (2014). "High Line Canal." from http://www.denverwater.org/Recreation/HighLineCanal/ Wimberly, M., et al. (2006). Digital forestry in the wildland urban interface. Computer Applications in Sustainable Forest Management G. Shao and K. Reynolds, Springer Netherlands. 11: 201 222.

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51 Appendix A. Site Worksheet

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52 B. In the field Worksheet Example