Research Note INT-RP-475
The Wilderness Threats Matrix: A Framework for Assessing Impacts
Application To Northern Region Wilderness
Research Note INT-RP-475
The Wilderness Threats Matrix: A Framework for Assessing Impacts
Application To Northern
Region Wilderness
To illustrate one application of the threats matrix, I conducted an assessment of threats to and impacts on the 15 wildernesses in the Forest Service's Northern Region. These wildernesses encompass more than 5 million acres (fig. 3). Each threat is briefly described, its most obvious impacts are mentioned, and a few basic references are provided. Finally, the significance of and current knowledge about the threats are evaluated.
Evaluation
Members of the Northern Region's Wilderness Interdisciplinary Team were given the threats matrix (fig. 2) and asked to evaluate the significance of and knowledge about the actual or foreseeable impacts each potential threat has had on each wilderness attribute. The criteria used to derive significance ratings were (1) extent and (2) importance. Extent refers to how many wildernesses experience the impact and the proportion of the wilderness that is impacted. This part of the rating is relatively objective.
Importance is more subjective and was based on an assessment of the likely longevity of the impact, the rarity of the attributes being impacted, and the extent to which ecosystem function is altered. Ratings were on a scale from 1 (low significance) to 5 (high significance). Highly important but localized impacts and very extensive but relatively unimportant impacts would be rated 3. An impact that is both moderately widespread and moderately important would also be rated 3. An impact that is unimportant would be rated 1 regardless of its extent.
Knowledge was also rated on a scale from 1 (little knowledge) to 5 (much knowledge). The types of knowledge under consideration were the nature, significance, extent, and severity of impacts. Knowledge about appropriate management or monitoring of these impacts was not considered. This is an important distinction because some impacts are quite well understood, although there is no cost-effective way to monitor them.
The criteria used to derive knowledge ratings were knowledge of cause-and-effect relationships and empirical data about the extent and severity of impacts. For example, if cause-and-effect relationships are obvious from common sense, but there is little data on extent or severity, the rating would be 3. Ratings are relative to each other and assess how much is known-not how much more needs to be learned. Ratings of 5 mean that cause-and-effect relationships are well understood with substantial empirical data on the impacts. A rating of 5 does not mean that much more could not be learned. Knowledge ratings were not assessed for impacts considered insignificant (those cells given a significance rating of 1).
Impacts of Recreation and Its Management
Recreational use of wilderness affects physical and biological resources (Hammitt and Cole 1987; Kuss and others 1990). Aquatic systems are affected when trails and other denuded areas erode, increasing sediment loads and turbidity, when waters are polluted by wastes from humans or livestock, and when fish are planted in fishless lakes. Soil and vegetation are severely affected along trails, in campsites, grazed meadows, and other areas where use is concentrated. Soils are physically, biologically, and chemically altered and, in some cases, eroded away because of impacts associated with recreation. Plants are injured and killed, reducing vegetation abundance and changing the community's composition. Animals are affected when recreationists disturb their habitat, approach them too closely, or kill them.
Recreational use can also result in conflict between wilderness visitors and diminish perceptions of solitude (Manning 1985). These impacts reduce opportunities for high quality wilderness experiences. Attempts to manage recreational use also cause impacts. Use restrictions can reduce access to the wilderness and diminish the "unconfined" nature of the recreational experience. Development of facilities to reduce resource damage can diminish the "primitive" nature of the experience. Facility construction, particularly trail construction, can also impact physical and biological resources.
These impacts occur throughout Northern Region wildernesses, although they are most severe in the more heavily used portions of the most popular wildernesses (such as lake basins in the Absaroka-Beartooth or the Cabinet Mountains and river corridors in Hells Canyon or in the Frank Church-River of No Return Wilderness). The most significant perceived impacts of recreation use in Northern Region wilderness are to aquatic systems, animals, and wilderness experience opportunities (fig. 4). Impacts on vegetation, soils, and cultural resources can be locally severe, but are of limited significance at the landscape scale. Our knowledge is greatest about impacts to vegetation, soils, and wilderness experiences. The greatest discrepancy between significance and knowledge is for impacts to aquatic systems and animals. Additional knowledge is needed for all types of recreational impact, but these two topics are particularly critical research needs.
Impacts of Livestock Grazing and Its Management
Livestock grazing is allowed in wilderness if it was an established use before designation. Moreover, guidelines contained in the Colorado Wilderness Act (P.L. 96-560) make it clear that Congress considers grazing in wilderness to be appropriate and intends that it be maintained. However, the trampling and grazing of sheep and cattle do cause impacts on physical and biological conditions in wilderness (Vallentine 1990). The physical, biological, and chemical characteristics of soils can be altered by grazing, as can the abundance and composition of vegetation. Aquatic systems and channel morphology can also be changed (Platts 1981). Visitors can be displeased when they encounter livestock or the evidence of livestock grazing. Fences, line cabins, water wells, stock tanks, and similar facilities also impact physical resources, wilderness, and experiences, as does the use of motorized equipment to maintain these facilities.
In 1991, about 14,000 animal-unit-months of grazing were permitted in Northern Region wilderness. Only six wildernesses had significant amounts of grazing (Absaroka-Beartooth, Gospel Hump, Lee Metcalf, Gates of the Mountains, Hells Canyon, and Anaconda-Pintlar). Given the limited grazing, significance ratings for grazing impacts were moderate on a regionwide basis (fig. 5). For individual wildernesses with livestock grazing, ratings would be much higher. Most attributes-other than air and, perhaps, animals and cultural resources-are significantly affected by grazing, where it occurs. For example, the vegetation of most Northern Region wilderness evolved without much grazing pressure from large ungulates. Consequently, much of the vegetation (such as perennial bunchgrasses) is intolerant of heavy and repeated defoliation.
Our knowledge about the effects of grazing is substantial, but virtually no studies have been conducted in wilderness. Additional knowledge is needed most for impacts to ecosystems/landscapes, wilderness experience opportunities, and animals. Wilderness management could profit greatly from the application of range management experience to the unique characteristics of wilderness.
Impacts of Mining
About 1,200 mining claims have been recorded in 12 Northern Region wildernesses. So far, however, claims have been validated only in the Cabinet Mountains Wilderness, where two mines are in the permitting stage. Past and present impacts, therefore, have been highly localized. The future is less clear, depending on the number of recorded claims determined to be valid and the type of operation used at each valid claim. Impacts can be substantial in the localized areas where mining activity reaches the exploration phase. They can be severe where development and production occur. Moreover, valid claims are real property that convey rights of access and can become private inholdings.
The impacts of mining can be the most intense impacts in wilderness. Vegetation and soils are likely to be highly disturbed at the mine site, and aquatic systems can be altered by acid drainage from mines or by chemicals used in the mining process, such as nitrates. However, in the Northern Region, mining impacts are now the most geographically localized of all significant threats to wilderness. Given this localized impact, the most significant impacts are likely to be to aquatic systems (fig. 6), because these impacts can extend long distances from the source of disturbance. Our knowledge about mining effects is substantial, particularly regarding impacts to soils and aquatic systems. Additional knowledge is needed most for impacts to ecosystems/landscapes, animals, and wilderness experience opportunities.
Impacts of Fire and Its Management
Fire is an important natural component of most wilderness ecosystems (Wright and Bailey 1982). Suppression of natural fire over the past half century or more has had substantial effects on many of these wilderness ecosystems (Kilgore and Heinselman 1990). Suppression of natural fires that ignited within wilderness and of natural fires that would have burned into wilderness are both of concern. Fire suppression activities generally decrease the frequency of fires and increase their magnitude. Larger, more intense fires will cause more pronounced nutrient and sediment flushes through aquatic systems, as well as more catastrophic changes in vegetation structure and composition, greater losses of soil organic horizons, and increased losses of nitrogen through volatilization. Periods between fires will be characterized by excessive organic fuel buildup, incomplete decomposition of biomass, and inhibition of nutrient cycling (Kilgore and Heinselman 1990). In addition, human-caused fires-either ignited in or burning into wilderness-can be considered adverse impacts, as can disturbances caused by firefighting.
The impacts of altering natural fire regimes are highly significant because fire plays such a critical role in the functioning of most ecosystems and because its effects are so widespread. This assessment suggests that the most significant impacts of fire and its management in Northern Region wilderness are to soils, vegetation, ecosystems, and landscapes (fig. 7). Our knowledge about fire effects is substantial, particularly regarding impacts to vegetation, soils, animals, aquatic systems, ecosystems, and landscapes. The greatest discrepancy between significance and knowledge is for impacts to soils, ecosystems/landscapes and wilderness experience opportunities. Fortunately, research on wilderness fire has received considerable attention in the past; hopefully, this attention will continue in the future.
Impacts of Exotic Species Introductions and Invasions
Many exotic species have been purposely introduced or have invaded the Northern Rocky Mountains since European settlement began in earnest in the late 19th century. A wide variety of exotic species now inhabit wildernesses, including plants from fungi to vascular plants, and aquatic and terrestrial vertebrates and invertebrates. Among the most significant introductions are:
The geographic extent of these introductions varies widely from the broadly distributed white pine blister rust, to the common but localized vascular plant introductions, to the highly localized fish introductions. Although fish introductions may originally have been confined to a few lakes and streams, these introductions may now have altered a substantial proportion of aquatic systems in wilderness.
The impacts of exotic introductions are less dramatic in Northern Region wilderness than perhaps in any other part of the United States, outside of Alaska. This reflects the harsh climatic conditions of the high-elevation mountain wildernesses, their large size, and the relatively low level of disturbance to surrounding lands. Nevertheless, some impacts are significant, particularly to aquatic systems and vegetation (fig. 8), and introductions could easily increase in the future. Our knowledge about exotic introductions is meager, except for the impacts of exotic plants on vegetation; even here, much more needs to be learned. The greatest discrepancy between significance and knowledge is for impacts to aquatic systems, ecosystems/landscapes, and animals.
Impacts of Water Projects
Wilderness conditions are affected by dams and water diversions within three wildernesses-the Selway-Bitterroot, Absaroka-Beartooth, and Rattlesnake. These dams raise the level of lakes and keep those levels more constant. They also diminish peak stream flows in early summer and prolong moderate flows through the summer. Of more significance is the effect of upstream dams and water diversions along the Snake River in the Hells Canyon Wilderness. Water projects can alter a stream's water temperatures, sediment loads, and chemical and biological characteristics as well as adjacent soils and vegetation (Ward and Sanford 1987). The headwaters of the Salmon River, which flows through the Frank Church-River of No Return and Gospel Hump Wildernesses are also outside of the wildernesses. These upstream waters are used extensively for irrigation, but there are no major water impoundments. Pollution of upstream waters can also affect wildernesses. Finally, all wildernesses that contain anadromous fish are affected by downstream dams that make migration to and from the ocean difficult (Nehlsen and others 1991).
Most of these impacts are highly localized and occur in only a small number of wildernesses in the Northern Region. However, where they do occur, these impacts can be highly significant. They can alter riparian habitat and impact rare and threatened taxa (such as certain races of salmonid fish). In other parts of the country, where headwater streams more commonly originate outside of wilderness, these impacts are likely to be much more significant. The most significant impacts of water projects in Northern Region wilderness have probably been to aquatic ecosystems and to streamside vegetation (fig. 9). Knowledge about these impacts is substantial, given the significance of the impacts. Additional knowledge is needed most for impacts to vegetation and ecosystems/landscapes.
Impacts of Atmospheric Pollutants
Both local and distant sources of atmospheric pollution can affect wilderness when polluted air enters wilderness. Even though Northern Region wildernesses are far from major pollution sources, they lie downwind of major industrialized and urban areas along the Pacific coast. Important pollutants include sulfur oxides (emitted during combustion of fossil fuels, smelting of ores, manufacturing of steel, and refining of petroleum), nitrogen oxides (emitted during combustion, primarily by vehicles), and volatile organic compounds (also emitted primarily by vehicles). Secondary pollutants, such as ozone and fine particulate matter, form when primary pollutants are transformed in the atmosphere. Pollutants can be transferred to the ground by dry and wet deposition, as well as by contact with low-lying clouds.
The potential impacts of atmospheric pollutants are great because they are so broadly dispersed and capable of altering the most basic functions of ecosystems (Schreiber and Newman 1987). Impacts include reductions in visibility and inputs to aquatic systems that change water chemistry, affecting the aquatic biota. Deposition on plants can injure them directly, but the most pervasive impacts might be the indirect effects of pollutants on soils, such as reduced nutrient availability, increased solubility of toxic metals, and reduced mycorrhizal development (Grigal 1988).
Northern Region wildernesses are less severely impacted than wildernesses in other parts of the country because there are relatively few significant local sources of pollution. Nonetheless, impacts to air, soils, vegetation, aquatic systems, and ecosystems/landscapes can be quite significant (fig. 10). Fortunately, the effects of air pollution have been studied extensively, and a number of studies have begun in wilderness. The greatest discrepancy between significance and knowledge is for impacts to ecosystems/landscapes, soils, and vegetation.
Impacts of Practices on Adjacent Lands
Practices on adjacent lands that affect wilderness include several threats that have already been discussed, such as emission of atmospheric pollutants, water projects, and fire management. Other activities on adjacent lands that can cause impacts include timber cutting, road construction, and urban development. These can pollute downstream waters, introduce exotic species, and adversely affect migratory animals (Glenn and Nudds 1989). These impacts can be particularly severe in wildernesses downstream from developed lands (Hells Canyon, Selway-Bitterroot, Frank Church-River of No Return, and Gospel Hump), as well as those that are relatively small. Although the Northern Region contains several of the largest blocks of wilderness in the United States, six wildernesses are smaller than 100,000 acres, or are fragmented with the fragments smaller than 100,000 acres. For these smaller wildernesses, particularly, wilderness must be managed as part of a larger landscape (Harris 1984). Fragmentation and development of the larger landscape affects large-scale ecological processes, flows of energy and materials, and disturbance regimes (Schonewald-Cox and Buechner 1992).
The impacts of practices on adjacent lands are quite substantial, particularly to animals, ecosystems/landscapes, and wilderness experiences (fig. 11). These external impacts are probably less severe in Northern Region wilderness than anywhere else in the United States outside of Alaska. This reflects the relative lack of development and low population in the Northern Rockies. In other parts of the country, these external impacts are likely to be much more significant. Our knowledge about impacts of practices on adjacent lands is sparse, particularly for impacts to ecosystems/landscapes, wilderness experiences, and to a lesser extent, animals. More research on these impacts is clearly needed.
Significance of Threats to Northern Region Wilderness
This analysis identifies those threats to Northern Region wilderness that are considered to be most significant and the wilderness attributes that are considered to be most threatened (fig. 12). This knowledge can help set regional priorities for wilderness management. The significance of each potential threat depends on the wilderness attribute being considered. For example, recreational use is a significant threat to wilderness experience opportunities but has little effect on air. Each potential threat is the most significant threat to at least one attribute. Fire and its management was considered the most significant threat to five of the nine attributes, while livestock grazing, water projects, and exotic species each were the most significant threat to only one attribute.
The mean significance rating, across all attributes (table 1), was greatest for fire and its management (3.4). This can be considered the most significant threat to the preservation of wilderness character in the Northern Region. Other threats with high mean significance ratings (2.7 to 2.9) were atmospheric pollutants, recreation, and practices on adjacent lands. Even threats with lower ratings-such as livestock grazing, exotic species introductions, mining, and water projects-have the potential to substantially impact wilderness; however, they are relatively limited in Northern Region wilderness. Livestock grazing would be a more significant threat in the southwestern United States, while exotic species introductions would be more significant in the southeastern United States. Threats from atmospheric pollutants and practices on adjacent lands would be more significant in the eastern United States, where wildernesses are typically small and close to urban areas. Water projects are likely to be a more significant threat in proposed Bureau of Land Management wildernesses, which typically do not contain headwaters.
Differences in significance among threats to attributes are greater than differences among the threats themselves. Seven of the nine wilderness attributes were considered the attribute most significantly impacted by at least one potential threat. Geological and cultural features were not the most significantly impacted attribute for any threat. Aquatic systems was considered the attribute most threatened by six different threats, and vegetation was considered the attribute most threatened by five different threats.
The mean significance rating for wilderness attributes, considering all threats (table 2), was greatest for aquatic systems (3.5). If aquatic systems are the most threatened of wilderness attributes, an immediate shift in priorities is needed. Most attention is being given to management of terrestrial systems in wilderness. Vegetation and ecosystems/landscapes also had high significance ratings of 3.3.
Research Gaps Concerning Threats to Northern Region Wilderness
By comparing significance and knowledge ratings, relative priorities can be assigned to each impact concerning the need for further research (fig. 13). I assigned a low priority to impacts with significance ratings of 2 or less, regardless of knowledge levels. I assigned moderate priority to those impacts with significance ratings of at least 3 and knowledge ratings at least as high as their significance ratings. Finally, I assigned high priority to impacts with significance ratings of at least 3 and knowledge ratings lower than their significance ratings. Of the 72 impacts (cells in the matrix), 37 (51 percent) are low priority, 21 (29 percent) are moderate priority, and 14 (19 percent) are high priority. While the high-priority impacts are in most immediate need of further research, all of the moderate-priority impacts and many of the low-priority impacts also need further study.
To extend this analysis to general conclusions about the relative priority of individual threats and attributes, I calculated a research gap index. I assigned values of 1 (low priority), 3 (moderate priority), or 5 (high priority) to each cell in the matrix. The research gap index is simply the mean of these rankings across all threats or across all attributes. This analysis suggests that fire and its management is the potential threat most in need of further research in the Northern Region (table 1). Threats with moderately large research gaps are exotic species introductions, practices on adjacent lands, atmospheric pollutants, and recreation. Threats that are the lowest priorities for further research in the Northern Region are mineral activities, livestock grazing, and water projects.
The attributes most in need of further study are aquatic systems and ecosystems/landscapes (table 2). Attributes with moderately large research gaps are wilderness experience opportunities, animals, vegetation, and soils. The attributes that are the lowest priorities for further research in the Northern Region are cultural resources, rock/landforms, and air. Again, even these lowest priorities are so poorly understood that more research is warranted.
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Title: Application to Northern Region Wilderness:
INT-RP-475 - The Wilderness Threats Matrix: A Framework for
Assessing Impacts
Electronic Publish Date: October 31, 1996
Expires: Indefinite
Last Update: January
15, 2002
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