A THESIS DOCUMENT
a comprehensive site design process for new development
located adjacent to wildfire hazard
areas in the montane zone of central Colorado.
...plan in full awareness of nature's forces, forms, and features--the sweep of the sun, the air currents, the peaks and the hollows of the earth, rock and soil strata, vegetation, lakes and streams, watersheds and natural drainage ways--and this awareness should obviously entail planning in harmony with the elements of nature. If we disregard them we will engender countless unnecessary frictions and preclude those experiences of fitness and compatibility that can bring so much pleasure and satisfaction to our lives.
John 0. Simonds
Landscape Archi tecture
Terrance G. Teague Thesis Candidate
Master of Landscape Architecture University of Colorado, Denver
May 24, 1979
TABLE OF CONTENTS
THESIS GOAL ?
THESIS OBJECTIVES HISTORICAL DEVELOPMENT
SOCIAL RELEVANCE ' 4.
SUMMARY OF RESEARCH &
FIRE ECOSYSTEMS &
CLIMAX ECOSYSTEMS 7
EAST SLOPE ECOSYSTEMS MATRIX PRIMEVAL POlMDEROSA PINE FORESTS INITIATION OF THE FIRE CYCLE
FIRE MAINTENANCE USED BY MAN 1'
^ILDFIRK BEHAVIOR 1
WILDFIRE CONTROL 11'
SITE DESIGN CRITERIA ^
SITE DESIGN PROCESS
PROGRAM METHODOLOGY n'
SITE ANALYSIS METHODOLOGY ^
CONCEPTUAL SITE DESIGN METHODOLOGY VISUAL METHODOLOGY ^
BIBLIOGRAPHY APPENDIX I
SITE DESIGN PROCESS FLOW CHART APPENDIX II
CASE STUDY APPENDIX III
Site design for a natural catastrophic event such as fire reflects an attitude of future realization which has not yet matured in this society. Flood planning is only now in the slow process of becoming widely acceptable. It will be another decade before wildfire planning becomes equally received. This thesis looks ahead to a time when the possibility of wildfire will help shape the built environment in the Montane in the same manner flood potential has begun to dictate the built environment in the flood plain.
Montane Colorado has evolved with fire just as it has with snow and wind, sun and cold. Over the last few million years fire has become a beneficial element within the ecosystem. When forced to survive without fire, as it is now, the ecosystem becomes unbalanced. The longer the imbalance, the weaker the system until inevitably it is endangered by an outside agent. The harbinger of that fire has appeared in the form of an insect which kills Ponderosa Pine, the principle species of the Montane. This insect is the Mountain Pine Bark Beetle. Once the insect has killed a forest, the dead trees become extremely combustible. It is as though the ecosystem was openly inviting fire.and in its present state the fire will be environmentally and socially tragic a wildfire.
The thesis simply states that because fire is an inherent part of Nature, man's environment must be compatible within that ecosystem to exist. The economical aspects of forest management as well as the tragic social consequences of wildfire are too overwhelming to ignore. The thesis propounds that if Montane society does not learn to plan with the inevitability of wildfire they may die by it.
To present and illustrate site design methodologies applicable in wildfire hazard zones of central montane Colorado.
1. To recognize montane ecological processes and their design implications.
.2, To base design on recognized probability of wildfire catastrophe.
3. To promote political/social acceptance through a visual analysis approach to the methodology.
To identify multi-use aspects of the methodology.
5. To illustrate this design methodology through a specific site located on undeveloped land in the montane zone.
The forest management practices of Northern Europe were well established in the 19th century. Earlier severe misuse resulted in timber shortages and a degraded environment. Within this climate a custodial awareness and concern emerged.
As early as 1886, California was using strips of "waste" land to block the frequent and intense fires of the chaparral. Rampant development during the 50s spread into the chaparral resulting in classic examples of "man/nature" catastrophes. A "fuelbreak program" began in earnest so that today over 2000 miles of fuelbreaks crisscross the California chaparral.
The front Range Vegetative Management Pilot Project, currently underway in the montane zone west of Boulder, Colorado, is a harbinger of future wide spread forest management in this state. Historical events similar to those of Northern Europe and California have resulted in severe wildfire hazards in areas which have adapted to fire as a necessary ecological event.
A forest fire that has burned 12,000 acres is less than a mile west of Allenspark. Firefighters from as far away as Idaho were called in to
fight the blaze which has been burning since Aug. 13.
The original pioneers and fortune seekers in Colorado's Montane have left a legacy of both visible and non-visible scars.. One major impact which is not commonly connected with their arrival is the destruction of the forest ecosystem. Lumber was indiscriminately stripped from the land and fire control was initiated. This practice of total fire prevention has persisted to the present day and has been a major prototype for fire department operations.
The current influx of settlers now arrivng are using the Montane for bedroom communities and creating urban sprawl in the Pront Range corridor. Between major population influxes, the forest ecosystems have regrown into a thicket of trees which for the most part has not seen fire for a century. Because of this tremendous imbalance, Nature has gone to extreme measures to produce an agent which establishes conditions highly conducive to fire. This agent is the Mountain Pine Bark Beetle. An insect is now doing the maintenance work which used to be done by fire. The beetle is thinning the forests, but unlike fire it leaves the dead trees in an extremely combustible state and is far less discriminatory than fire.
This combustible forest is the environment in which modern man is living and attempting to preserve as part of the "mountain experience". Tragic wildfires will be the result of this widespread social belief. Unfortunately, the predicted social response will be more efficient fire"fighting systems wh'ich, in turn, will further compound the ecological problem and its resulting potential for catastrophe.
summary of thesis research
Many natural systems have become adjusted to fire, containing organisms that have developed recovery mechanisms and fire adaptations proportional to fire frequencies. Some systems are fire dependent, possessing organisms that require fire to maintain health and complete life cycles, with fires functioning as essential decomposition and recycling agents, and with frequent light fires oft'en preventing fuel buildups and thus severe fires. hire intensities are usually inversely proportional to frequencies. Other systems contain relatively fire-fhee environments in which natural ignition and the conditions conducive to'burning rarely occur. If fires do occur they act as catastrophic forces.
Thebiota, soils, and local environments of some systems were modified by primitive ^ man's use of fire. Recent upset and damage have occured because of indiscriminate and profuse burning and, conversely, because of attempts to exclude fire completely from systems in which fire was an important natural component.
Mature strives to maintain balances. When the existing quasi-equilibrium is naturally disturbed or.upset, phenomenal forces are a-massed in the recovery and restoration of stability. Man's perturbations are often so frequent that instability prevails, or are so severe and unnatural that degraded and undesirable steady states .become established.
fire and the ecosystem
1. hire Independent
rain forests swamps
2. hire Dominated
lodgepole pine chaparral formations
3. Fire Maintained
ponderosa pine grasslands giant sequoia h. hire Initiated
eastern white pines coastal douglas fir
Location of ridge top and slope stands
Location of volley stand------------X
mop by r.t.f.
Fig. 1. EaBt Slope of the Front Range in Boulder County, Colorado
Contour Interval 500 Feet Seale In miles
T.....2 4 5
UNIVERSITY OF COLORADO STUDIES
"The trees are large and noble in aspect and stand widely apart, except in the highest parts of the plateau where the spruces predominate. Instead of dense thickets where we are shut in by impenetrable foliage, we can look far beyond and see the tree trunks vanishing away like an infinite colonade. The ground is unobstructed and inviting.
There is a constant succession of parks and glades--dreamy avenues of grass and flowers winding between sylvan walls, or spreading out in broad open meadows, i'rom June until September there is a display of wild flowers which is quite beyond description. The valley sides and platforms above are resplendent with dense masses of scarlet, white, purple, and yellow. It is noteworthy that while the trees exhibit but few species the humbler plants present a very great number, both of species and genera..."
C.iÂ£. Dutton (1880-1881)
primeval ponderosa pine forests
The original ponerosa pine stands were more savanna or parkland than true forests. All size classes were represented and arranged in a mosaic pattern of distinct groups, rather than in an admixture of all types as found in climax forests.
Grasses and needles cover the ground providing a suitable environment for frequent fires (approx. 10 year intervals) which acts as a "decaying" and recycling mechanism. Seedlings start on bare ground in openings with good nursery conditions. Seeds are supplied from surrounding groups.
Most of the seedlings are recycled and young trees are thinned by fire. Surface fire through mature groups eliminates competing species and destroys lower branches which further stimulates rapid and straight growth. The bark is composed of resin cemented scales which
when ignited, loosen and fall to the
fire maintenance used by man
The United States Forest Service has recognized that fire can be safely-used on a prescribed basis to maintain the forest ecosystem. To determine the ease of control of a fire, a set of guidelines is given based on Available Fuels, Weather and Topography. When the various conditions are acceptable, a controlled burn can be used to remove dead wood and young trees. Controlled burns are cost efficient because they allow nature to do most of the work.
Prescribed fire reduces wildfire hazard by*
1. Reducing volume of dead, highly flameable fuels and repeated burns keeps them at low levels.
2. Thinning dense thickets of pine sapling and pole-size stands,
3. Raising green foliage level through needle scorching.
4. Destroying shade tolerant trees and likev/ise the "ladders" which carry fire aloft.
The general behavior and intensity prediction of most forest fires is predicated on landform, diurnal cycle, surface winds and fuel availability. Although the specific behavior of wind is a function of many variables, in Central Montane Colorado they almost always have westerly components, especially those which create intense' fires. The other factors can be well defined. From these factors, designers can anticipate probable wildfire direction and intensity.
The State of California has been practicing preventive wildfire control on its chapparal landscapes for 100 years. The state of the art appears to be a zonal approach to fuel reduction. as a wildfire burns through a preventive wildfire control area, less and less fuel is available as it nears the fireline where there is none.
The different zones are listed below:
1. Fireline _ ________
(2'-10' wide mineral soil)
(20'-30' periodic treatment) 3. Fuelbreak
E. Fuel Modification Practice (large area)
Each zone is designed to control and stop a particular type of fire. The Fuel Modification Area is designed to control a rampant crown fire. The Fuel break is used to reduce the rate of burn of a crown fire and therefore the total heat output. The Firebreak stops the crown fire and the Fireline stops the ground fire. The zones are reversed on the other side to make spot fires easily controllable.
ft. } *> 1
site design criteria
The thesis research has revealed a number of Site Design Criteria which are vitally important for the Health, Safety and Welfare of those inhabitants of Colorado's central montane zone.
The criteria which follows concerns basic issues which should be addressed in all elements of the site design. In general, the criteria directs design decisions so that the possibility of catastrophic wildfire impacts on human development becomes the primary form determinant. The basic Site Design Criteria is listed as follows:
1. Slopes greater than 307, are considered too dangerous for structures in the event of a wildfire.
2. Wherever possible, structures and access roads are to be located in "Buildable Areas as determined by the Site Analysis Methodology, Invariably these "Buildable Areas" will be a Fire-Maintained^ Ecosystem,
3. Major access roads should always provide at least two routes for egress in the event of a wildfire .
4. Any Major Wildfire Pattern which directly impacts the site (see Site Analysis Conclusion) should be broken by various levels of preventive wildfire treatment, such as firelines, firebreaks, fuelbreaks, etc.
The extent of preventive wildfire treatment is proportional to the severity of the hazard.
site design process
The Site Design Process has been diagramed in a flow chart type format. The process flow chart is divided into four major methodologies. The discussion which follows explains the various steps contained within each methodology. At this point it might be helpful to review the flow chart while reading the text which follows.
To further illustrate the Site Design Process, a case study has been provided. The case study area, known as Boulder Heights is typical of the potentially dangerous situation which exists throughout the Montane Zone of Central Colorado. The case study assumes an undeveloped site, except for the access road through the area. Although the entire thrust of the thesis addresses undeveloped sites, the same process can be used to provide post-development safety improvements.
In this methodology the client determines the general requirements which the development must have to be economically feasible. In most programs, some form of market feasibility study is used to determine the physical design requirements. It is not the intent of this thesis to define an appropriate program because there are many appropriate possibilities. It is the intent of this thesis to show optimum interactions between the Program Methodology and the overall Site Design Process.
The property line of Boulder Heights is shown only as a means to show the study site. It is assumed that additional land can be purchased if the Process dictates.
The Program Methodology is divided into four major development categories. The discussion which follows describes these categories and their associated assumptions.
-SOLAR POTENTIAL--Due to energy considerations, this program must be located on the land to take advantage of solar energy potential. The method used for defining that suitable land is a Slope Orientation Overlay which defines the optimumum solar window as a range from southwest to southeast. All other orientations are considered less than satisfactory and as such are shown as shaded areas.
-WATER AND WASTE WATER REQUIREMENTS--This category has been defined such that it is independent of any site design implications. The Program Methodology assumes that a self-contained re-cycle treatment system is available. If this category was site dependent, that is, if septic systems and wells had to be located, then appropriate overlays could be generated to help locate the optimum conditions.
-LAND-USE--It is assumed that the client will use the information developed in the Site Analysis Methodology to determine the optimum land-use. Note that the process line is connected to the Conceptual Site Design Methodology.
-ACCESS ROUTES--Like the Land-Use category, it is assumed that access requirement will be determined by the site, and as such a process line is connected to the Conceptual Site Design Methodology.
site analysis methodology
The Site Analysis Methodology looks at basic wildfire determinants to illustrate where combinations of factors occur to magnify the frequency and intensity of wildfire. Likewise the methodology defines those areas where wildfire intensity would be low if the fire process had not been excluded from the montane region. The analysis assumes that widespread fuel modification programs are inevitable along the Front Range because of insect infestations and severe wildfire conditions threatening human settlements.
It is important to note that the Site Analysis Methodology does not predict the possibility of a fire, but it does locate areas where fires under the right conditions could become catastrophic. The Analysis is designed only to look at those factors which endanger the Health, Safety and Welfare of human activity. Wildfire is the only major natural hazard which is ubiquitous over the entire montane landscape. The Site Analysis Methodology begins to shape the human systems much the same way as nature has used the Fire Methodology to shape the montane ecosystem.
The Site Analysis Methodology can be used with a range of technological applications. Data gathering and resolution can be highly technological (computers and remote sensing) which also means high cost. An alternate approach would be to use "appropriate technologies" which sacrifice data gathering and resolution but would be low cost and quickly accomplished.
The case study uses the.appropriate technological approach so that it can be:
-easily communicated to the general public and their elected officials -be used quickly by site designers to determine a general site design concept
-be readily affordable
The Site Analysis Methodology begins with the compilation of data in four general categories.
1. PROBABLE AREAS OF FIRE INITIATION
2. TOPOGRAPHICALLY INDUCED STRONG WIND FACTORS
3. SLOPE ANALYSIS
4. FIRE ECOSYSTEM ANALYSIS
Information from each category is put on a transparent overlay. Those areas which tend to induce wildfires are shaded. Each category is illustrated in its own identifying color, so that composite overlays can be differentiated. Also those areas which tend to be adversely affected by all or most of the categories will appear as gray or "mud" colored.
-PROBABLE AREAS OF FIRE INITIATION--This category recognizes that modern man starts many more fires than nature. Those areas within the landscape which are heavily used by man will also be areas where fire will probably start.
The central issue involves higher fuel and heat concentrations than occur naturally. Fuel storage has become a necessity for montane living. Because of fuel combustion, heat is present.
The combination of fuel and heat become the starting point for the investigation. The higher the concentration of fuel and heat the more significant its possible role in fire initiation.
The case study seems to be typical of montane development, in that the areas identified are located along valleys, note the effect if a fire is started in these low areas. The burn rate is increased when moving up a slope.
When this type of fire initiation area is compared to natural fire initiation areas, they tend to be located on entirely different landscapes.
The natural fire starting area is usually a sparsely covered hilltop which is susceptible to lightning strikes. If a fire is started, it must burn down the slope which is less than optimum resulting in a slow, small intensity fire.
In the case study, the Town of Jamestown and the small settlement of Sunshine stand out as areas of fire initiation. The highway along Left Hand Canyon seems to generate enough use so that its impacts are significant. The general area is covered with isolated dwellings but unless they are concentrated their assumed effect is negligible.
-TOPOGRAPHICALLY INDUCED STRONG WIND ANALYSIS--Some attempt must be made to document wind pattern as it flows over the land. Those areas which are exposed to west wind should be defined because a fire on those slopes could turn into a sizable wildfire very quickly.
In the Montane zone of Central Colorado, strong winds (greater than 25 knots) come out of the west 95% of the time. Winds from other directions are not considered in the methodology.
Given the parameters of wind direction and topography, a computer analysis could be performed to determine a range of exposed areas, much like a wind tunnel. The result would be a wind model.
Usually the required wind exposure information is so basic that a common sense understanding about the mechanics of air motion around objects is all that is necessary. Slightly more advanced approaches could use wind "experts" to locate areas of west wind exposure, or ecologists to "read the land" for signs of wind impact, or use monitoring devices to actually measure the wind.
A preliminary wind analysis can be done if a few basic principles are kept in mind:
1. Ridges and high points are usually wind blown.
2. If a ridge runs north-south, the west face can be considered wind exposed. If the ridge varies from the north-south line, then it becomes less exposed as the angle increases.
3. Valleys which run east-west will funnel the wind.
4. Saddles between high points tend
to funnel wind. '
The procedure for mapping a preliminary wind exposure overlay is easily learned. Simply shade those areas of high wind exposure, leaving the sheltered areas. Where it appears that the west wind will "leave the ground", draw in a broad arrow. Where the wind is funneled, darken the shade.
The case study clearly locates tv/o broad areas of high wind exposure:
Corridor A--Along Jim Creek and Left Hand Canyon.
Corridor B--Along Left Hand Creek and up a west facing slope into the study site.
It should be clearly noted that Wind Corridor B directly impacts the site. The west facing slope will be exposed to high wind exposure up to the ridge-top where it leaves the ground.
-SLOPE ANALYSIS--This category documents important information for three general areas of concern:
1. The burn rate as a function of slope
2. The cost of construction to develop access roads and buildings
3. The Slope Aspect which is a combination of the Slope Analysis and Slope Orientation.
At a slope of 307, or greater the burning process tends to generate
significant wind from the rising heat *ol
alone. A slope change from 0 to 307. yb Jo
doubles the rate of burn and likewise
a change from 30 to 60% redoubles it
again. When west facing slopes are
also steep slopes (greater than 307.) ,
a wildfire could easily result.
The cost of construction as it relates to slope is a well documented issue. The cost/slope parallel is mentioned here because it tends to reinforce the argument regarding the comprehensive nature of the Site Design Process for all development in the Montane Zone.
-FIRE ECOSYSTEM ANALYSIS--This category is the central issue of the thesis. If nature can develop mechanisms and forms in an ecosystem which can turn the problem of fire into an opportunity, then why can Man not plan and design his developments likewise? Within a natural Fire-Maintained Ecosystem, fire is a life-sustaining process which allows the ecosystem to stabilize itself against disruptive forces.
In order to design with fire, it is imperative to isolate those ecosystems within the Montane Zone which are Fire-Maintained, Fire-Dominated and Fire-Independent. Those general areas which can be classified as Fire-Dominated are of the, utmost' concern because of their inherent high rate and intensity of burn.
The higher the intensity, the more expensive and difficult it is to ensure the "Health, Safety and Welfare" of human settlement within that ecosystem. That type of fire is too great a force to contend with economically and aesthetically. The amount of effort necessary for protection would require a long-term maintenance effort because the natural forces will tend to restore the original ecosystem.
The analysis methodology for the Fire Ecosystem involves locating Fire-Dominated Ecosystems. Within the Lower Montane Zone, the stands which tend to be fire-dominated are ponderosa pine and douglas fir mixes. The grasslands and ponderosa pine are considered Fire-Maintained and therefore safe.
It should be noted that a Fire-Maintained Ecosystem which has had no fire excluded or no management treatment for ten years or more, is a potentially dangerous situation.
Natural fire will still tend to occur on a 10-year cycle (more or less) but the intensity of burn will approach that of a Fire-Dominated Ecosystem.
The Fire Ecosystems are rated as follows:
1. Untreated Fire-Maintained
2. Fire Dominated
The technique for gathering this ecosystem data can be as detailed and sophisticated as the particular situation dictates. It is analagous to the Topographically Induced Strong Wind Analysis category- where a variety of techniques presented here can be used by landscape architects to map the necessary data.
Most of the Fire Ecosystem Analysis can be done from current aerial photographs and topographic maps.
When looking at an aerial of this study region in the Lower Montane, there exists two basic densities of tree cover depending on exposure.
In almost all cases, those stands on the north side will tend to be Fire-Dominated and those on the south will tend to be Fire-Maintained. Field checks must always be done after the aerial study.
Within the Upper Montane, the percentage of Fire-Dominated Ecosystems increase because of greater moisture levels. The south facing slopes will still tend to be Fire-Maintained.
It should be noted that Fire-Independent Ecosystems exist in both Montane Zones, principally along the creeks. Aspen stands can be considered Fire-Independent as can other deciduous tree stands. These ecosystems have a very long cycle between fires and therefore are classified with Fire-Maintained Ecosystems as safe.
In the case study, four stand types were identified; ponderosa pine-douglas fir and douglas fir-ponderosa pine (Fire-Dominated) and ponderosa pine and grassland (Fire-Maintained). Because of the widespread thinning program in the area, ponderosa pine areas were considered Fire-Maintained.
From the resulting overlay, it can be seen that the pattern of Fire-Dominated Ecosystems reflects the landform patterns, generally running east-west. Fire-Independent ecosystems were insignificantly small.
After the four site analysis overlays have been completed as well as any program overlays, the designer is ready to assess the possible impact from a wildfire. The methodology has been designed so that a composite of overlays will reveal the most dangerous situations, as those areas where color build-up is maximized.
The designer should identify all Major and Minor Wildfire Patterns which directly impact the study site. The degree of continuity of the Wildfire Patterns should be noted. When one or more of the overlays breaks the Pattern, it too should be recorded for later use in the Conceptual Site Design Methodology. A major continuous Wildfire Pattern is the most dangerous situation which occurs in the Montane Zone.
Note the two Major Wildfire Patterns in the case study; The first Pattern runs from west to east along Jim Creek and Left Hand Canyon. Note the contributing factors: 1) the Town of Jamestown,
2) steep slopes, 3) Fire-Dominated Ecosystems and 4) the funneling effect of the wind down the canyon. The resulting Wildfire Pattern is a result of the worst situation from each of the analysis overlays.
The second major pattern occurs south of the first, also running west to east along Left Hand Creek and heading directly for the study site. This pattern becomes extremely dangerous on the west facing slope which rises up from Glendale Gulch. A wildfire on this slope would not be humanly controllable. Once at the top of that slope, the pattern continues through the study site. In those areas where the composite of overlays identifies as a Major Wildfire Pattern, human development would be foolish.
The composite also reveals Safe Areas within the study site which are free of wildfire factors. This then becomes the area most suitable for human development. Once again it should be noted that these Safe Areas will by no means be free of fire, quite the contrary. Fire will tend to burn these areas frequently but at vastly reduced intensities.
conceptual site design methodology
The first step in this methodology is to address those Major Wildfire Patterns which directly impact the site. The possibility of a wildfire entering the site through these Patterns must be significantly reduced. The ultimate goal is to stop the advance of all three components of a wildfire. They include ground fire, crown fire and wind blown spot fires. The minimum goal is to allow enough time to send out an alarm and begin emergency planning.
If modification of a Major Wildfire Pattern is necessary, three of the four general analysis categories can be reviewed for possible solutions.
From the analysis of Probable Areas of Fire Initiation, those impacting areas within the Wildfire Pattern should be closely reviewed for necessary safety improvements.
The local Fire Department can be used to this end.
Using the Slope Analysis and topographic information, all areas within the Wildfire Pattern which have a significant change of slope are the best locations to defend the site from wildfire intrusion. Such areas may include ridge tops, drainage ways, or possibly a bench in continuous slope.
The Fire Ecosystem Analysis locates Fire-Dominated Ecosystems which to a large extent defines the Wildfire Pattern. Where the Fire-Dominated Ecosystem crosses the Optimum Defensible Area, a major effort should be made to convert the ecosystem through transition zones such as Firelines, Firebreaks, Fuelbreaks and Fuel Modification Areas.
A Fuelbreak 100-200 feet wide is located over (and around) the Optimum Defensible Area. The longterm maintenance cost of a Fuelbreak can be reduced'significantly if a different type of Fire Ecosystem can be introduced and stabilized.
Such conversions can be realized if the existing moisture levels within the Fuelbreak can be changed. For example, by diverting the surface runoff from a stand of naturally dense ponderosa pine/douglas fir, a stabilized ponderosa stand could be maintained with less thinning effort. Even if the moisture level can be changed, the area designated as Fuelbreak must be thinned to an open, savanna type setting. The optimum situation would be a large and mature stand of ponderosa pine.
The "conversion methodology" recognizes the two basic areas of manipulation, the successional state of an ecosystem through thinning and artificial changes in existing moisture levels can help dictate a different1 climax ecosystem. Large areas can have the spring runoff diverted from an area intended as a Fuelbreak/Fire-Maintained Ecosystem. The diverted runoff could be directed to a Fuelbreak/Fire-Independent. The concept is to let the natural forces absorb some of the costs of long-term maintenance.
Outside of the Fuelbreak a larger area called a Fuel Modification Area can be designed depending on the severity of the Wildfire Pattern. A Fire-Dominated Ecosystem located on a west facing slope would require considerable effort. This type of area is designed with the intent of reducing the tremendous heat from a crown fire. The intensity decreases further when the wildfire begins burning through the Fuelbreak. The ground fire burns through the Firebreak and is stopped by the Fireline which could be a road, creek or rock outcropping.
The order of treatment is reversed on the other side of the Fireline to reduce flare-up due to spot fires.
Once the Major Wildfire Patterns have been modified to protect the study site from extreme catastrophy, interior modifications may be necessary. Any Minor Wildfire Patterns within the site should be effectively isolated from the Safe Area as defined in the Site Analysis Composite.
The Safe Area is a Fire-Maintained ecosystem vjhere fire intensities are low. The proposed concept for development is similar to the design concept used in a medieval city, with its concentric protective walls. With each successive internal zone development densities increase until the innermost zone contains not only the highest density but also the most valued buildings.
A typical three zone development scenario might read like this: the outer ring is comprised of 10 acre, executive homes, followed by one acre single-family homes, followed by a zone of multiplexes and community services. The greatest number of people are thereby afforded the greatest amount of protection and security.
Access route location can then be addressed. The Major Access Road should be located around the edge of the central zone on the side of possible wildfire approach. This will double as the final Fireline of protection. This Major Access Road should connect to two different regional access routes so that two egresses are available. One of the Major Access Branches should be located along the safest possible route, clear of Wildfire Patterns. The other branch might be used effectively as a Fireline within an approaching Wildfire Pattern.
Around the other zones, collector roads as Firelines can be located. Structures within each zone should be designed with its own Firebreak and Fireline to reflect the possible direction of the approaching Wildfire. Access drives to the individual structures can act as Firelines to protect the structure.
This methodology assumes that the designer has accepted the realization that such a large scale ecosystem treatment will be visible for all to see. The issues of Health, Education and Welfare are so pressing that the treatment areas are predetermined in the design process and the Visual Methodology accepts this conclusion.
If a zonal treatment is used for ecosystem modification, then it must recognize the land form as the basis for design. Within the treatment area, the Fireline becomes the most visible aspect and should therefore be.located on the most interesting micro landscape. Where the land reaches a climax of visibility, so too should the modification design.
The Conceptual Site Design Methodology has already identified areas within the landscape where there are significant changes in slope as the optimum locations for the modification treatment. These ridges and drainage ways are also the most visible within the landscape. By accentuating these areas, the large scale change can become publicly acceptable because it is ecologically believable.
If a ridge has been identified as a treatment area, then the vegetation should be "backed off" down the slope from the top. A gradual transition from one treatment zone to the next will mimic eco-logic transition. The Fireline could be a rock outcropping or a road. The Firebreak becomes a grassland with a few specimen trees. The Fuelbreak becomes a .sparcely tree covered savanna and the Fuel Modification Area becomes a Fire Maintained Ecosystem. This transition from one treatment zone to another takes place over the land ending at the drainage ways.
ho'matter how slight the drainage ways, the transition zones must recognize them. Allow those species comprising the Fire Independent Ecosystems to come up the slope along the drainage. Within the natural landscape, vegetation is always thickest along the drainages and so it should remain. The maximum modification will take place at the top of the drainage to allow sufficient space for the other zones. Throughout the upper zones allow the drainage a linear focus by leaving groups of specimen trees.
If a drainage way has been identified as the optimum treatment area, then the design approach must increase the visibility of that line within the landscape. Leave enough specimen trees to help define the drainage way. On either side of the drainage, establish an open Fuelbreak transending into the larger fuel Modification Area which will reflect the land on which they are formed. The width of the overall treatment zone is a function of the side slopes. The steeper the slope, the wider the treatment area. In this way, ridges descending down to the drainage will be accented.
The inter-site treatment is also responsive to landform, but on a more detailed level. The Fuelbreak around a structure will have to be designed so that trees and groupings of trees are arranged to compliment man made objects and the land-form. The possibilities for arrangement are maximized when dense forest must be thinned. In this manner, potential "good" views can be opened up and less pleasing objects can be concealed. However, the greatest depth of the Fuelbreak should still be in the direction of possible wildfire approach.
Visual interest can be heightened within the Fuelbreak by increased attention to ground detail, the introduction of Hire Independent species and the careful arrangement of conifer specimen trees. Increasing ground detail can involve numerous different interpretations, ranging from the seeding of grasses and wild flowers to the introduction of native shrubs. Designers should note that large groupings of such shrubs as Scrub Oak, Three-leaf Sumac and Mountain Mahogany are Fire Dominated ecosystems and should not be located near structures. If additional water is available, Fire Independent trees such as harrow-leaf Cottonwood and Aspen can be grown to increase the visual interest especially when used in conjunction with conifers to fill in the "voids".
"Design with fire" does not have to involve a stockade approach to site design. Just as the natural system has developed beauty while using fire, so to can Man's sites be attractive as well as functional.
All too often, our building sites respond only to our needs leaving many environmental compromises. Unfortunately in the Montane, the forces which determine wildfire are so powerful that few long term compromises can be made.
in many ways this thesis has attempted to outline an optimum process and an optimum solution. If the necessary design steps were followed, it would be possible to return to a time when the natural order maintained our environment. A time when fire was as necessary as the rain and almost as prevalent. Naturally this ideal condition will never again be realized in full, but without this ultimate goal, there will be little that can be called environmental design in Montane Colorado.
Arthur, Louise M. and Hon 3. Boster. Measuring Scenic beauty:
A Selected Annotated Bibliography (USDA forest Service General Technical Keport RM-25). fort Collins, Colorado: u.3. Dept. of Agriculture, May 197b.
Biswell, Harold H., and others. Ponderosa fire Management:
A Task force Evaluation of Controlled Burning in Ponderosa Pine forests of Central Arizona. Tallahassee, florida: Tall Timbers Research Station, 1976.
Cairns, J. Jr., and others, eds. Recovery and Restoration of Damaged Ecosvs terns. Charlottesville: University of Virginia Press, 1977.
Daniel, Terry C. and Ron S. boster. Measuring Landscape
esthetics: The Scenic Beauty Sstimation Method (U3DA
forest Service Research Paper RM-167). U.S. Dept, of Agriculture, May 1976.
fire Committee of SwIfCO. Guide to Prescribed fire in the Southwest. Southwest Interagency fire Council, 19b8.
fosberg, Michael A., and others. Estimating Airflow Patterns Over Complex Terrain (USDa forest Service Research Paper RM-162). fort Collins, Colorado: U.o. Department of Agriculture, March 1976.
fuel Management Planning ana Treatment Guide: Prescribed
Burning, forest Service Northern Region, u.S. Dept, of Agriculture.
Gaylor, Harry P. Wi Id fires: Prevention and Control. Bowie Maryland: Robert J. Brady Company, 1974.
Green, Lisle R. fuelbreaks and Other fuel Modification for Wildland fire Control (Agriculture Handbook No. 499). Washington, D.C.: forest Service, u.S. Department of Agriculture, April 1977.
Hansen, Wallace R., and others. Climatographv of the front Aange Urban Corridor and Vicinity. Colors do (Geological Survey Professional Paper 1019). Washington: U.S. Department of the Interior, 1978.
Marr, John W. Ecosystems of the East Slope of the front aange in Colorado (no. 8 in a series of University of Colorado Studies Series in Biology). Boulder, Colorado: University of Colorado Press, february 1967.
Myers, Clifford A. Multipurpose Silviculture in Ponderosa
Pine Stands of the Montane Zone of Central Colorado (USDA forest Service Research Paper RM-132). fort Collins, Colorado: U.S. Dept, of Agriculture, December 1974.
national forest Landscape Management: Vol. I and II, Agriculture Handbook Numbers 434, 462, 4-78, 483 and 484. Washington, D.C.: Forest Service, U.S. Department of Agriculture,
Schroeder, Mark J. and Charles C. Buck. fire Weather: a Guide for Application of Meteorological Information to rorest Lire Control Operations (Agricultural handbook 36O) Washington, D.C.: forest Service, U.S. Department of Agriculture, May 1970.
Uniform fire Code. U. S. A., 1976.
SITE ANALYSIS METHODOLOGY
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