AUTHORS

Bruce G. Marcot is the regional wildlife ecologist in the Ecological Framework for Management Research, 

Development, and Application Program, Pacific Northwest Research Station, U.S. Department of Agriculture, Forest Service in Portland, Oregon. Michael J. Wisdom is the technology transfer scientist at the 

Starkey Experimental Forest, Pacific Northwest Research Station, U.S. Department of Agriculture, Forest 

Service in La Grande, Oregon. Hiram W. LI is a professor in the Department of Fish and Wildlife at Oregon 

State University in Corvallis, Oregon. Gonzalo C. Castillo is a graduate student at Oregon State University 

in Corvallis, Oregon.
Managing for Featured, 

Threatened, Endangered, and 

Sensitive Species and Unique 

Habitats for Ecosystem 

Sustainability

Bruce G. Marcot, Michael J. Wisdom, Hiram W. Li, and 

Gonzalo C. Castillo

From Volume III: Assessment

Paul F. Hessburg, Science Team Leader and Technical 

Editor

Eastside Forest Ecosystem Health 

Assessment

Richard L. Everett, Assessment Team Leader

Published by: 

U.S. Department of Agriculture, Forest Service 

Pacific Northwest Research Station 

General Technical Report PNW-GTR-329 

February 1994

In cooperation with: 

U.S. Department of Agriculture, Forest Service 

Pacific Northwest Region
ABSTRACT

Marcot, Bruce G.; Wisdom, Michael J.; Li, Hiram W.; Castillo, Gonzalo C. 1994. Managing for featured, threatened, endangered, and sensitive species and unique habitats for ecosystem sustainability. 

Gen. Tech. Rep. PNW-GTR-329. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station. 39 p. (Everett, Richard L., assessment team leader; Eastside forest ecosystem 

health assessment; Hessburg, Paul F., science team leader and tech. ed., Volume III: assessment.)

The traditional approach to wildlife management has focused on single species—historically game species 

and more recently threatened and endangered species. Several newer approaches to managing for multiple 

species and biological diversity include managing coarse filters, ecological indicator species, indicator 

guilds, and use of species-habitat matrices. These and other modeling approaches each have strong points as 

well as weak points, which include conflicts among objectives for species with disparate needs. We present 

three case examples of integrating management for single species with management for multiple species and 

ecosystems. These examples are: managing elk habitat in the Blue Mountains of eastern Oregon; managing 

for sustainable native fish faunas in eastern Oregon and Washington; and managing plant and animal species closely associated with old-growth forests in the Pacific Northwest. Each case illustrates a unique set 

of considerations and ecological conditions. Successful integration of species and ecosystem management 

depends on clearly defining objectives at several scales of time and space, and not violating the three most 

basic principles of ecosystem management: maintaining or restoring biodiversity, maintaining long-term site 

productivity, and maintaining sustainable use of renewable resources.

Keywords: Wildlife habitat, fish habitat, biodiversity, eastside, threatened species, endangered species, sensitive species, management indicator species, species planning.
Contents

INTRODUCTION .......................................................................................................................... 1

METHODS FOR INTEGRATING SPECIES AND ECOSYSTEM MANAGEMENT ..................... 1

Coarse-Filter and Fine-Filter Species Management ............................................................... 1

Managing With Ecological Indicator Species .......................................................................... 2

Managing With Indicator Guilds .............................................................................................. 3

Managing With Species-Habitat Matrices ............................................................................... 3

Managing With Other Modeling Approaches .......................................................................... 3

Further Considerations for Managing Species and Unique Habitats ...................................... 4

INTEGRATING SPECIES AND ECOSYSTEM MANAGEMENT: THREE CASE STUDIES ....... 5

Example 1: Managing for Elk in the Blue Mountains of Eastern Oregon ................................ 5

Example 2: Managing for Sustainable Native Fish Faunas in Eastern Oregon and

Washington ...................................................................................................................... 16

Management for Species Closely Associated with Old-Growth Forests of the

 Pacific Northwest ............................................................................................................. 21

DISCUSSION, CONCLUSIONS, AND RECOMMENDATIONS ................................................... 25

ACKNOWLEDGEMENTS ............................................................................................................ 27

REFERENCES ............................................................................................................................. 28

GLOSSARY ................................................................................................................................ 36

1

INTRODUCTION

Biological diversity has been described as the variety of life and its processes (Keystone Center 1991). 

Managing for biological diversity on lands administered by USDA Forest Service includes species management. Species-specific management of plants and animals is a traditional approach focusing both on amount, 

distribution, and quality of habitat, as well as key environmental factors such as food, cover, and water 

(Leopold 1933). The single-species orientation has included managing a sustainable, harvestable surplus of 

fish and wildlife game species; maintaining habitat for featured species and management indicator species; 

protecting sensitive and State-designated rare species; and recovery of Federally designated threatened and 

endangered species.

In recent years, however, other aspects of biological diversity have been recognized as natural resources 

worth conserving (Hansen and others 1991, SAF 1991). These include unique, scarce, and declining habitats, 

such as old-growth forests and riparian vegetation not disturbed by human activities, and entire plant and 

animal communities and ecosystems. Traditional approaches, however, which focus on individual species 

and their habitats might inadequately provide for these new management objectives (Noss 1991, Thomas and 

others 1993).

As a result, a new management paradigm has emerged within the USDA Forest Service, focusing now 

as much on biological diversity and ecological processes as on individual species. Within this context of 

ecosystem management, three main themes are appearing: maintaining and restoring biological diversity 

(including conserving species, populations, genomes, and communities); maintaining long-term site productivity; and maintaining long-term sustainability of use of renewable natural resources. These three themes 

collectively encompass and surpass (but should not supersede) the traditional species focus for management. 

Conflicts in site-specific management objectives have arisen in early attempts to merge these broader goals 

with those of the traditional species-specific approach.

In this paper, we discuss some of the recent methods proposed for species management within the larger 

context of ecosystem management of biological diversity. We explore some potential conflicts and propose 

resolutions. Next, we present three case studies of integrating species-specific management objectives into 

an ecosystem framework. We conclude with general recommendations for integrating the species focus with 

broader ecosystem management objectives. This paper focuses on managing biological resources; economic 

and other resources will require additional consideration.

METHODS FOR INTEGRATING SPECIES AND 

ECOSYSTEM MANAGEMENT

The challenge forest managers face today is to manage threatened, endangered, indicator, featured, game, 

and sensitive species in a context that also conserves biological diversity, site productivity, and sustainability 

of resource use. In this section, we discuss some of the proposed approaches: coarse-filter and fine-filter species management, ecological indicator species, indicator guilds, and use of species-habitat matrices.

Coarse-Filter and Fine-Filter Species Management 

Coarse-filter species management (Hunter 1990, 1991; The Nature Conservancy 1982; Noss 1987) assumes 

that conserving land areas and representative habitats, such as old forests or streamside zones, will provide 

for the needs of all associated species, communities, environments, and ecological processes. In contrast, a 

fine-filtered approach specifically provides for only the habitats, substrates, and conditions for a single or few 

species. An example is the Forest Service’s management requirements for pileated woodpecker (Dryocopus 

pileatus).
2

The efficacy of a coarse-filter approach has seldom been tested. An example is the coarse-filter management 

program proposed by The Nature Conservancy (1982), which has estimated that 85 to 90 percent of target 

species would occur within their representative ecosystems. Another example of testing a coarse-filter approach is the viability assessment of plant and animal species associated with old-growth forests of Washington and Oregon in the range of the northern spotted owl (Strix occidentalis caurina), as conducted by 

Thomas and others (1993). They demonstrated that, to ensure protection of the complete old-growth forest 

community, a coarse-filter approach to conserving old growth would still have to consider a wide variety 

of rare and locally endemic species and other species of the upland forests at a species-specific scale. Their 

evaluation demonstrated that the fine-filter approach to managing habitat for the northern spotted owl would 

provide for only about a third of all plants and animals closely associated with old-growth forests within the 

owl’s range in National Forests. Hence, the conclusion is that, to ensure conservation of the entire old-growth 

community, a combination of both coarse-filter management for single species and fine-filter management 

for multiple species would be needed. Additional details of this case are discussed below.

The coarse-filter approach is appealing in its cost savings. However, assumptions that a complete community 

or assemblage of plants or animals would be provided needs to be evaluated on a case-specific basis.

Related to the coarse-filter approach is the use of umbrella or flagship species, which are usually large, charismatic birds or mammals with broad distributions or area needs. The working assumption—seldom tested, 

and likely not often valid—is that managing habitats for umbrella or flagship species adequately provides for 

the host of all other species found in those habitats. One example of the flagship-species approach is management of forest reserves for tigers (Panthera tigris) in India.

Managing With Ecological Indicator Species

Another approach to multiple-species management is through the use of ecological indicator species. An 

ecological indicator species is one whose presence, distribution, and population trend is assumed to index 

those of other species associated with a common geographic area or habitat. The more effective indicator 

species chosen for management have narrow tolerances to environmental conditions; such species readily 

respond to changes in those conditions.

The USDA Forest Service uses ecological indicator species to simplify developing and implementing 

management guidelines (Sidle and Suring 1986). The indicator species concept was originally developed to 

evaluate how the vitality of a particular species—commonly, but not always, a plant—reflects the overall 

trophic health of its environment. Examples of using indicator species for management include: assessing 

richness of algae species as an index to the degree of aquatic eutrophication (Nygaard 1949); lichen species indicating continuity and overall health of conifer forests (Tibell 1992); vascular plants correlating with 

condition of pastureland in Great Britain (Helliwell 1978); presence and abundance of litter spiders indexing forest recovery after clearcutting (McIver and others 1990); and tiger beetles indexing overall biological 

diversity (Pearson and Cassola 1992). Other examples are found in the literature.

In recent years, however, much doubt has been cast on the assumption that any forest vertebrate species can 

adequately indicate the specific population size and trend of other vertebrate species (Landres and others 

1988, Morrison and others 1992, Patton 1987). This use of ecological indicator species typically fails because each species has its own unique niche and distinctive response to environmental conditions, and differs from other species in morphology, behavior, resources used, competitive interactions, and other biological and ecological characteristics (Morrison and others 1992). Moreover, coincidence in population size or 

trend between two or more species does not necessarily lead to an understanding of the cause. This is problematic if the indicators are used to test management standards. Discerning whether species are responding 

to the same conditions as the indicator species is impossible.

Ecological indicator species are but one type of “management indicator,” that is, a quantifiable property of 

an environment that correlates with desirable conditions (for example, Hunsaker and others 1990). Man-
3

agement indicators other than ecological indicator species are legitimate and useful tools for tracking and 

predicting environmental conditions and trends, such as for ecosystem recovery (Kelly and Harwell 1990) or 

for management of biodiversity (Noss 1990, Williams and Marcot 1991). Some of these tools are described 

below.

Managing With Indicator Guilds

An approach related to that of ecological indicator species is that of using species guilds to simplify assessing effects or devising management standards (Hunter 1990). In this approach, a guild of species having 

similar ecological characteristics is treated as a group. Guilds may be composed of ecologically similar species from very diverse taxa. For example, some rodents, birds, and ants may be within one guild of seed-eating species. The assumption—seldom tested and likely not often valid—is that all species of the guild will 

respond similarly to changes in environmental conditions.

Morrison and others (1992) evaluated such a “guild indicator” approach to species management of forest 

birds. They concluded that fundamental ecological differences between species of a guild typically resulted 

in individual species responding differently—sometimes with opposite numerical responses—to environmental conditions. Thus, to be reliable, a guild indicator approach to multiple-species management requires 

case-specific empirical testing.

Managing With Species-Habitat Matrices

Another approach to multiple-species management is the use of species-habitat matrices. Species-habitat 

matrices depict the relative quality of vegetation associations and seral stages for various life needs, typically 

for reproduction, feeding, and resting or cover. Also depicted is information on use of sundry vegetation substrates and components, such as snags and down wood and logs. One of the original species-habitat matrices 

was developed for eastern Washington and Oregon (Thomas 1979). This early work led to the formation of 

the Wildlife-Habitat Relationships Program within the USDA Forest Service, including creation of specieshabitat matrices among other regions and ecological provinces (Salwasser and others 1980).

Species-habitat matrices have been used in forest planning to help identify forest types, conditions, and seral 

stages, and special habitats—such as cliffs, caves, lakes and ponds, riparian vegetation, snags and wildlife 

trees, and down logs—for managing multiple species of wildlife (Patton 1992, Toth and others 1986). Validation studies of these matrix models (Dedon and others 1986, Laymon 1990, Raphael and Marcot 1986), 

however, have demonstrated that their most effective use is for forest planning over the scale of watersheds 

and landscapes, rather than for predicting individual population responses to stand-scale conditions and 

changes.

Managing With Other Modeling Approaches

Other approaches to assessment and management of multiple species include models of habitat and population response. For example, Hansen and others (1990) modeled responses of wildlife habitats to management 

and to change in climate. This habitat response model could then be used in conjunction with information on 

species-habitat relationships to predict trends in vertebrate community composition over broad areas, such as 

was predicted from empirical studies of terrestrial vertebrates in northwestern California (Raphael and others 1988, Raphael and Marcot 1989).

In a mathematical approach, Hof and Raphael (in press) developed an optimization model for predicting the 

most equitable combination of habitats (forest types and their seral stages) that would meet management 

objectives for multiple species simultaneously. In a similar but qualitative approach, Toth and others (1986) 

used species-habitat matrices to develop schematics of forest habitat patch layout patterns that would meet 
4

the needs of multiple species requiring two or more kinds of habitats.

Still other population and habitat modeling approaches include: habitat capability and suitability index models; habitat evaluation procedures; Bayesian and pattern recognition models; models of optimal foraging; 

population viability models; wildlife community structure models; and models of vegetation structure, stand 

growth, and forest succession. Attributes and examples of these models were reviewed by Morrison and others (1992).

This brief summary of a few of the more popular approaches to multiple-species assessment and management underscores our conclusion that no short cut to evaluating species’ responses and requirements exists. 

Instead, the traditional species focus needs to be continued but must be integrated into an ecosystem context 

as our knowledge and tools for analysis become more sophisticated.

Further Considerations for Managing Species and Unique Habitats 

Several National Forests have integrated management for multiple species combining the most stringent requirements among a set of species. For example, the Tahoe National Forest in California (Chapel and others 

1992) and Tongass National Forest in Alaska (Samson and others 1989) developed management recommendations for conserving old-growth forests for wildlife. In the Pacific Northwest, similar old growth management recommendations were developed for threatened species, species deemed to be at risk of extirpation, 

and groups of species sharing similar ecologies. This last example, which identified management needs 

incrementally, is discussed below.

Management of unique habitats can entail a different approach that includes mapping the location and extent 

of the habitat and superimposing proposed management activities to identify areas of potential conflict. 

Also, by use of area analysis or cumulative effects analysis, the effects of off-site and previous management 

activities can be identified, mapped, and evaluated to help determine how they influence conservation of 

desired habitat conditions on site. This entails the use of area analysis or cumulative effects analysis.

Another consideration in management for species and unique habitats is the effect of such management on 

the sustainability and productivity of the land for other organisms and objectives. For example, protection 

of large forest stands from timber harvest, silvicultural manipulation, and fire control might induce higher 

risks of insect outbreaks and stand-replacing fires. This is especially true if such stands had previously been 

protected from natural fires and, as a result, changed in composition or accumulated a high fuel volume. 

Emphasis on management for single objectives that ignores either fire hazards or the need for a natural fire 

regime might adversely influence future ecological conditions. A good knowledge of disturbance dynamics 

of each ecosystem is needed. Such knowledge can be gained from reconstructing historical locations, frequencies, and intensities of disturbances such as fires and outbreaks of forest insects. Historical fire atlases, 

and retrospective studies on past vegetation conditions and disturbance dynamics, are two tools that will be 

in greater demand under a broader ecosystem management approach.

Management alternatives that affect plant and animal species have been traditionally considered in local 

contexts only. Management practices commonly have been implemented at stand and subdrainage scales 

without explicit consideration of broader areas. Recently, however, the Forest Service has begun to conduct 

hierarchical analyses in space and time to assess the collective needs of plant, fish, and terrestrial wildlife 

populations and species. They are now bringing together, over large spatial scales and long time frames, 

each of the essential components of landscapes, watersheds, basins, and regions that collectively meet the 

long-term habitat requirements of featured, threatened, and other species. They have only begun to evaluate 

ecosystem diversity, productivity, and sustainability.

In this spirit, nested scales of space and time should be considered when assessing effects, when defining 

management objectives and desired future conditions, and when developing mitigations and management 
5

standards and guidelines. In a dynamic forest ecosystem and landscape, desired future conditions are not 

necessarily a single, static state; rather, they can be expressed as a span of conditions. For example, Caraher and others (1992) described a range of natural conditions of various attributes of the Blue Mountains in 

northeastern Oregon.

In this type of analysis, a major factor is the potential for conflicts among simultaneous management objectives. For example, consider an approach to optimize and balance the needs of multiple objectives, such 

as for featured, game, rare, sensitive, threatened, or endangered species. Some game species require early 

successional vegetation. For example, black-tailed deer (Odocoileus hemionus) require shrub openings close 

to hiding cover. And hunters require road and trail access to the deer. In the same general landscape, another 

species might require a very different condition. As examples, Brotherella roelhi, a rare species of moss, is 

closely associated with old-growth and closed canopy conditions in the Pacific Northwest. Although not an 

old-growth obligate, wolverines (Gulo gulo) and grizzly bears (Ursus horribilis) require large roadless tracts. 

Thus, landscape and vegetation conditions that would maximize one species might be antithetical for conservation of another. Only by considering all needs and objectives at the onset can habitat requirements of multiple species be optimized. Examples of conflicting objectives and a resolution method are discussed below.

More often than not, when managing for multiple species and ecosystems, we are faced with a dearth of information on environmental conditions and species’ life histories, ecologies, and population status. Although 

developing management guidelines under such conditions is possible, we emphasize the need for basic 

information, particularly value- and resource-free inventories and classifications of ecological conditions. In 

the Pacific Northwest, much information is needed on status, trends, and habitat relationships of many plant 

and animal species. Such information can be gathered through basic research, inventory, and monitoring 

programs, and evaluated for use in an adaptive management framework.

Additional management considerations are outside the scope of this paper and include social, political, and 

economic effects, as well as effects on abiotic resources, such as water quality, visual resources, air quality, 

and roads.

INTEGRATING SPECIES AND ECOSYSTEM MANAGEMENT: THREE 

CASE STUDIES

We offer three examples of integrating management for species with management for ecosystems: managing elk (Cervus elaphus) in the Blue Mountains of eastern Washington and Oregon, managing fish species 

and stocks in eastern Washington and Oregon, and managing plant and animal species closely associated 

with old-growth forests in western Washington, Oregon, and California. The purpose of presenting these 

examples is to show that solutions to ecosystem and multiple-species management are typically case-specific 

and no one approach applies to all. Despite differences in methods, the objectives among these examples are 

similar and attempt to maintain species viability and ecosystem health, productivity, diversity, and sustainability.

Example 1: Managing for Elk in the Blue Mountains of Eastern Oregon

In this example, we apply principles of landscape ecology to managing diverse wildlife guilds. The setting 

for this example is the Blue Mountains Province of northeastern Oregon and southeastern Washington. Our 

intent is to stimulate new paradigms for wildlife and ecosystem management. To this end, we demonstrate a 

hypothetical method to evaluate landscapes in a holistic manner, for a featured species and some dissimilar 

wildlife guilds. We also discuss landscape designs to accommodate these divergent needs. Our example uses 

species and guilds composed of large mammals and birds because their life requisites are better known than 
6

those of most amphibians, reptiles, and small mammals. Consequently, our discussion and example apply to 

the spatial scales commensurate with the home ranges and dispersal distances of large vertebrates, typically 

areas of subwatershed and watershed scales. Subwatersheds in the Blue Mountains generally range from 

1000 to 10,000 acres. Watersheds, as aggregates of subwatersheds, generally range from 10,000 to 50,000 

acres.

However, for a complete analysis of wildlife use of landscapes, smaller spatial scale evaluations, such as of 

an individual tree, snag, log, or vegetation stand, also are required. These scales are especially important 

when considering the needs of small mammals, amphibians, reptiles, and some resident birds, which often 

have substantially smaller home ranges than do large mammals and other birds. In our example, however, 

we do not discuss the effects of individual sites and stand structures per se. Rather, we focus on the effects 

of vegetation patch sizes and arrangements at scales of the subwatershed and watershed. Such an analysis 

should be considered a complement to stand-scale management.

Historical elk management: emphasis on game species—Wildlife managers have traditionally emphasized the production of game species for consumption. Management usually focused on producing a single 

species for a single user group. Nongame species, without benefit of a strong constituency, often were given 

little attention. Moreover, the ecological role and effect of game management rarely was addressed in the 

context of a functioning ecosystem.

In North America, many game species use two or more distinct types of habitat to meet life requisites. These 

“multitype” species benefit from close proximity of different seral stages (Thomas and others 1979). Hence, 

wildlife managers often have advocated fragmenting habitat patches of different seral stages to maintain a 

high edge effect. Their intent was to maintain two or more desired habitats, each representing a distinct seral 

or structural stage, close to one another to meet multiple-habitat requisites within the species’ home range 

(Thomas and others 1979).

Leopold’s Game Management (1933) reflected this approach. Leopold developed his law of interspersion 

(1933:129-132) at a time when wildlife management was just emerging as a science in North America. He 

was the first scientist to use edge effect as a popular concept (also see Lay 1938). Although it has been 

recently challenged (Harris 1988, Reese and Ratti 1988), this paradigm remains a popular and ecologically 

sound approach for managing multitype or edge-associated species (Guthery and Bingham 1992).

Examples of multitype species in the Blue Mountains include elk, wild turkey (Meleagris gallapavo), blue 

grouse (Dendragapus obscurus), mountain bluebird (Sailia currucoides), northern flicker (Colaptes auratus), great horned owl (Bubo virginianus), and great gray owl (Strix nebulosa). Such species benefit from 

interspersion of habitat patches, along with a useful ecotone between the patches (Guthery and Bingham 

1992). In general, the useful ecotone is the edge that occurs between young and old forest seral stages or between grassland and forest, referred to as “high contrast edge” by Thomas and others (1979). Edges between 

mid-seral and old forests, for example, likely are not used by these multitype species as frequently as are 

edges between young and old forests (Thomas and others 1979).

A myriad of other wildlife species do not benefit from, and often are adversely affected by, high interspersion or fragmentation of habitat patches (Harris and Silva-Lopez 1992, Morrison and others 1992). These 

“unitype” or habitat-interior species are associated primarily with one seral or structural stage. (The categories of unitype and multitype species are a simplification for management purposes; it is difficult to categorize some species as either type.) Examples of habitat-interior species in the Pacific Northwest have been 

identified in field research studies by Hansen and others (1990), Lehmkuhl (1990), Lehmkuhl and others 

(1991), Lehmkuhl and Ruggiero (1991), Marcot (1985), and Rosenburg and Raphael (1986). These studies 

identified various species associated with large or interior conditions of forest stands (such as varied thrush 

(Ixoreus naevius), Hansen and others 1990) or clearcuts (such as western wood peewee (Contopus sordidu-
7

lus), Marcot 1985). Such species generally respond negatively to a high contrast edge between young and old 

seral stages; they persist optimally in large habitat patches that contain minimal edge and maximal interior. 

In general, as the area of interior habitat increases, so does the likelihood of occurrence and persistence of 

unitype species associated with the patch (Morrison and others 1992).

Persistence of unitype species also depends on the connectivity of like habitat patches across the landscape. 

In general, the shorter the distance between and among like patches, the higher the probability of sufficient 

connectivity to maintain adequate population size. Adequate population size is defined as that needed to 

withstand stochastic declines in breeding, dispersal, and survival that threaten a species’ persistence at defined spatial and temporal scales.

Much attention has been given to landscape designs that minimize fragmentation and enhance connectivity 

of old forest patches (Franklin and Forman 1987, Lamberson and others 1992). Examples of species likely to 

benefit from such designs in the Blue Mountains include northern goshawk (Accipiter gentilis), Townsend’s 

warbler (Dendroica coronata), pileated woodpecker (Dryocopus pileatus), black-backed woodpecker (Picoides articus), Vaux’s swift (Chaetura vauxi), northern flying squirrel (Glaucomys sabrinus), and Townsend’s 

big-eared bat (Plecotus townsendii).

Other unitype species may persist in large habitat patches of early seral stages (Hansen and others 1990, 

Marcot 1985). Examples in the Blue Mountains include mourning dove (Zenaida macroura), chipping 

sparrow (Spizella passerina), American goldfinch (Carduelis tristis), Brewer’s blackbird (Euphagus cyanocephalus), Columbian ground squirrel (Spermophilus columbianus), and northern pocket gopher (Thomomys 

talpoides).

Few if any unitype species in the Blue Mountains seem to be closely associated with mid-seral forest stages. 

The sharp-shinned hawk (Accipiter striatus) appears to come closest; it makes extensive use of mid-seral 

forests but also forages in both young and old forests. Thus, it is more a multitype species than a unitype 

species.

Landscape relationships of elk and unitype species—How are landscapes used by dissimilar guilds, especially when one species is “featured,” perhaps to the detriment of others? If we knew the answer, we might 

understand a bit more about ecosystem management for wildlife. We attempt here to describe how landscapes of the Blue Mountains are used by a featured species in relation to wildlife guilds that have highly 

dissimilar needs.

We chose elk as the featured species because it is designated as “featured” by nearly every National Forest 

in which it occurs, including those of the Blue Mountains. We contrast this species’ predicted patterns of use 

with those of unitype or habitat-interior species for three distinct landscapes. Ecological relationships that 

form the basis for this evaluation are described as follows (also see table 1).

Elk: a multitype species—Elk is an edge-associated species that responds positively to increasing fragmentation of seral stages (Thomas and others 1988, Wisdom and others 1986). Landscape management of elk 

involves two complementary strategies: manipulating their spatial and temporal distribution through effective land treatments; and controlling their population size and manipulating their sex and age composition 

(population structure) through effective harvest regimes.

The first strategy, commonly referred to as “elk habitat effectiveness,” is defined by Lyon and Christensen 

(1992:4) as the “percentage of available habitat that is usable by elk outside the hunting season.” This percentage is a gross index of the ability of land managers to “grow elk” and influence their distribution.

The second strategy, coined as “elk vulnerability,” is defined as “the susceptibility of elk to being killed during the hunting season” (Lyon and Christensen 1992:3). Elk vulnerability pertains to the ability of population managers to manipulate the number and population structure of elk through hunting (Thomas 1991).
8

Models of habitat effectiveness predict the relative distribution of elk within and among habitat patches by 

subwatershed. Predictions are based on elk response to the interspersion and quality of habitat patches and to 

the density of roads. Thomas and others (1988) developed a habitat effectiveness model for elk winter ranges 

in the Blue Mountains that predicts elk distribution based on four variables: size and spacing of forage and 

cover patches; density of roads open to motorized traffic; quality of cover patches; and quantity and quality 

of forage (table 1).

Models of elk vulnerability are under development. The variables thought to significantly increase elk vulnerability to harvest include: high density of hunters, high density of roads, loss or absence of large cover 

patches, and gentle terrain (Thomas 1991). Effects of these and other variables on elk harvest are shown in 

tables 1 and 2.

Unitype species associated with old forests—Many species in the Blue Mountains are associated with old 

(late-successional, including mature and old-growth) forests. Few data exist, however, about specific responses of these species to changes in patch size, amount, and arrangement. We therefore borrow principles 

of landscape ecology derived from other provinces and regions for our discussion here.

In general, the occurrence and persistence of species associated with old forest patches increases with increasing patch size and connectivity of such patches, as described earlier and as summarized by Morrison 

and others (1992). Moreover, microclimate inside old forest patches is modified with increasing distance 

from openings. For example, Chen and others (1992), working in southern Washington and central Oregon, 

found evidence that extremes in microclimate were partially or fully modified within interior portions of 

forest patches of old-growth Douglas-fir (Pseudotsuga menziesia) that exceeded 150 yards from openings 

(young forests). Also, susceptibility to windthrow likely decreases with increasing size and interior portions 

of old forest patches.

Moderation of thermal environment and reduction in windthrow along edges are confounded by physiography (Chen and others 1992). For example, an old forest patch exposed on a ridgetop and surrounded by 

young forests likely is more susceptible to windthrow and is subject to greater extremes in weather than a 

similar patch downslope. The relations described above are generally predictable (table 1) but require local 

adjustment to account for effects of physiography.

Table 1—Descriptive effects of landscape changes on elk and unitype species within subwatersheds of 

the Blue Mountains

Elk Unitype Species

Landscape Changes HE[1] ES[2] Young Forest Old Forest

Increasing fragmentation or edge effect Positive[3] Negative Negative Negative

Increasing road density and human uses Negative[4] Negative Negative Negative

Increasing size and connectivity of old forest patches Variable[5] Positive Negative Positive

Increasing size and connectivity of young forest patches Variable[6] Negative Positive Negative

[1] Habitat Effectiveness

[2] Elk survival during hunting season; Negative = low survival or high vulnerability to harvest; Positive = high survival or low 

 vulnerability to harvest

[3] Increases HE related to size and spacing of habitats (HEs)

[4] Decreases HE related to density of open roads (HEr)

[5] Increases HE related to covefquality (HEc); decreases HE related to size and spacing (HEs)

[6] May increase HE related to forage quantity and quality (HEf); decreases HE related to size and spacing (HEs)
9

Table 2—Landscape problems that increase elk vulnerability to harvest and the corresponding 

landscape remedies (from Thomas 1991:319)

Landscape Problems Landscape Remedies

1. Increasing density of roads 1. Design roads to minimize effects. Close roads 

 permanently or temporarily. Enforce road closures

2. Increasing density of hunters 2. Restrict hunter numbers

3. Decreasing amounts of cover 3. Control stand configuration, juxtaposition, and size 

 through modifications in timber management program

4. Fragmenting of cover into smaller patches 4. Retain adequate escape cover in the form of stands of 

 several hundred or more acres

5. No restriction on antler class in bull harvest 5. Impose regulations on what can be taken — such as 

 allowing the kill of spike antlered bulls only

6. Setting of open seasons that include the rutting period 6. Ensure that open seasons do not include the rutting 

 period.

7. Improving technology 7. Preclude “modern” weapons

8. Long open seasons 8. Shorten the open season

9. Relatively gentle terrain 9. Decrease road density, maintain more cover, increase 

 size of cover patches, decrease hunter numbers

10. Increasing number of hunter days 10. Related to both items 2 and 8 above. Reduce hunter 

 numbers or reduce length of hunting season, or both

Unitype species associated with young forests—In contrast to species associated with old forests, even 

fewer data are available about the response of young forest-associated species to landscape change. This subject has been largely ignored by researchers of landscape ecology. Working in young-growth Douglas-fir in 

northwestern California, Marcot (1985) found that, on average, 25 percent of the variance in bird abundance 

that was not explained by site conditions was explained by landscape attributes. Such attributes included 

slope angle, slope position, distance to nearest permanent water, distance to next nearest similar habitat, 

habitat patch size, and number of different edges (adjacent stands). For example, during the breeding season, variation in abundance of western wood pewees, warbling vireos (Vireo gilvus), and western tanagers 

(Piranga ludoviciana) was accounted for by proximity to the next nearest shrub patch. During the winter 

season, chestnut-backed chickadees (Parus rufescens), cedar waxwings (Bombycilla cedrorum), and evening 

grosbeaks (Coccothraustes vespertinus) exhibited this pattern. However, the majority (71 percent) of the 91 

bird species observed showed no correlations with landscape attributes. Autecological studies are needed to 

better determine landscape relationships of species associated closely with young seral stages.

Although data are scant, it is logical to assume that unitype species associated with young forests respond 

similarly to patch size and arrangement of their selected habitats, as do unitypes that use old forests. That 

is, species occurrence and persistence can be expected to increase with increasing size and connectivity of 

desired patches (table 1).

Landscape distribution of elk and unitype species—Both multitype and unitype species appear to respond to a common attribute: distance from edge between young and old forests. Hence, this attribute can be 

used to evaluate the probability of species or guild use of habitat patches within a subwatershed. (Other attributes could be similarly evaluated.) Predicted use can be described in terms of a relative probability distribution, which is defined as the relative proportion of time or area that a habitat patch is used by a species or 

guild. Probability distributions of use of distance bands from edges can be scaled from 0.0 to 1.0, where 1.0 

represents 100 percent probability of use by a species or guild relative to other areas having probabilities less 

than 100 percent. Similarly, 0.0 is equal to 0 percent probability that a particular area is used. The sum of all 

probabilities within a subwatershed, weighted by area, equals the composite, relative probability of species 

or guild use for the subwatershed as a whole.
10

Thomas and others (1988) defined elk use of habitat patches in this manner. Their size and spacing variable described a probability distribution for elk by 100-yard distance bands from edges, into both forage 

and cover areas in a given subwatershed (table 3). Thomas and others (1988) defined forage areas as patches 

with an overhead canopy closure of 40 percent or less. They defined cover areas as patches with an overhead 

canopy closure exceeding 40 percent. They further classified cover into two types: marginal cover, which 

are patches with overstory canopy closure of 41 to 69 percent having overstory trees 10 to 39 feet tall; and 

satisfactory cover, which are patches with 70 percent overhead canopy closure and overstory trees 40 feet 

tall or taller.

We used these definitions to determine that forage areas are analogous to young forests, marginal cover is 

analogous to mid-seral forests, and satisfactory cover is analogous to old forests. Meaningful edge is the 

ecotone between forage areas and marginal or satisfactory cover, but not between marginal and satisfactory 

cover (Thomas and others 1988).

These concepts can also be applied to unitype species. What follows must be considered a working management hypothesis that requires rigorous testing and validation. We present this hypothesis as a first attempt 

to implement landscape evaluation and management of unitype wildlife guilds. It is not a tool to predict 

absolute probabilities of species occurrence or persistence. It may be useful, however, in estimating the 

relative “fitness” of subwatersheds for these guilds, and in demonstrating the relative likelihood of guild use 

within and among habitat patches. (Also, the caveats given above—that species within indicator guilds often 

display disparate numerical responses to environmental conditions—also should be tested for this example.) 

The following five assumptions form the basis of our working management hypothesis:

▪ Assumption 1: Unitype species distribute themselves positively and incrementally away from meaningful edge. Meaningful edge in the Blue Mountains is between young and old forests, or between 

young and mid-seral forests. Definitions of forage and cover areas for elk (Thomas and others 1988) 

can serve as interim descriptors of young versus mid-seral or old forest patches, respectively, until 

new research provides more specific definitions.

Table 3--Hypothetical probability distributions of elk and unitype species in relation to distance from 

edge between young, mid-seral and old forest patches

- - - - - - - - Relative probability distribution - - - - - - - -

Distance from edge [1] (yards) Into Elk Young forest species Old forest species

young forest (elk forage areas)

0 -100 1.00 0.25 0.00

100 - 200 0.54 0.50 0.00

201 - 300 0.54 1.00 0.00

301 - 500 0.14 1.00 0.00

> 500 0.04 1.00 0.00

Into mid-seral forest (elk marginal cover)

0 -100 1.00 0.00 0.125

101 - 200 0.14 0.00 0.25

201 - 300 0.14 0.00 0.50

> 300 0.005 0.00 0.50

Into old forest (elk satisfactory cover)

0 -100 1.00 0.00 0.25

101 - 200 0.14 0.00 0.50

201 - 300 0.14 0.00 1.00

300 0.005 0.00 1.00

[1) Edges are defined as the ecotone between young and mid-seral forests, and the ecotone between young and old forests.
11

▪ Assumption 2: Unitype species that use old forests are distributed most positively (with a use index 

value of 1.0) in portions of old forest (elk satisfactory cover) that exceed 200 yards from an edge 

with young forest (elk forage areas). Mid-seral forest (elk marginal cover) is used by unitypes as 

well, but highest use is suboptimal (use index value of 0.5) to that of old forest. Areas of mid-seral or 

old forest over 200 yards from edges of young forests represent the interior portions of habitat that 

experience the least variation in microclimate and least susceptibility to windthrow. Also, habitat-interior species are more vulnerable to predation by edge-associated species with increasing proximity 

to edge (Harris and Silva-Gomez 1992). We assume that the distribution of old forest species thus 

declines linearly with increasing proximity to edge with young forest, with none of the young forest 

edge itself used (use index value of 0.0). Table 3 summarized these hypothesized probability distributions of use by 100-yard distance bands from meaningful edge into early-, mid-, and late-seral 

stages.

▪ Assumption 3: Unitype species closely associated with young forests are distributed most positively 

(use index value of 1.0) in portions of young forests greater than 200 yards from an edge with midseral or old forest. We hypothesize that the distribution of young forest species declines linearly with 

increasing proximity to edge with mid-seral or old forest, with none of the mid- and late-seral forest 

edge itself used (use index value of 0.0) (table 3).

▪ Assumption 4: Effect of variations in vegetative structure and composition on abundance of unitype 

species within and among habitat patches is not specifically addressed in this example and is assumed to not influence species distribution and abundance. These variations include individual structures such as snags, logs, and trees, as well as composition of overstory and understory woody and 

herbaceous vegetation. Response of Blue Mountains fauna to management of these stand-scale attributes has been addressed previously (Thomas 1979). Our hypothesis is designed as a complement 

to stand-scale management, not as a substitute. That is, we assume that stand-scale management of 

vegetation structure and composition for wildlife is already underway in the Blue Mountains. We further assume that unitype species respond to patch size and arrangement described here only if forest 

structures desired by such wildlife are well distributed across the associated patches and seral stages. 

If these stand-scale needs are not actively managed, our hypothesis is invalid.

▪ Assumption 5: We assume that our hypothesis is more applicable to subwatersheds under even-aged 

silvicultural forest management than to more complex stand structures resulting from uneven- or 

all-aged management. Even-aged silviculture typically results in seral stages that can be delineated 

and identified as distinct patches. By contrast, uneven-aged treatments often result in patches that 

contain elements of multiple seral stages; distinct patches (and edges) may not be evident. Effects of 

uneven-aged management on unitype guilds require more intensive evaluation at the stand scale, and 

responses of wildlife may be independent of patch size or arrangement.

Also, a comprehensive list of unitype species for ecosystems of the Blue Mountains is not available. Such a 

list should be developed as part of the research required to test this hypothesis.

Evaluating subwatersheds—Our hypothesis can be applied to ecosystems of the Blue Mountains to demonstrate the theoretical effects of subwatershed management on disparate wildlife guilds. We did so by 

applying the probability distributions in table 3 to three subwatersheds of the Umatilla National Forest. 

Subwatersheds were selected to reflect three distinct landscapes: subwatershed 1 is dominated by patches of 

large, relatively unfragmented young forests (fig. 1); subwatershed 2 contains patches of large, relatively unfragmented mid-seral and old forests (fig. 2); and subwatershed 3 is composed of highly fragmented patches 

of all seral stages (fig. 3).
12

Acreages of all seral stages within each 100-yard distance band away from edge in each of these three test 

subwatersheds were estimated by using a geographic information system and software developed by Hitchcock and Ager (1992). Summaries of the distance band analyses are shown in figures 1, 2, and 3. The results 

(table 4) show dramatic differences in probability distributions of potential use by elk and unitype guilds 

among the three subwatersheds. As expected, subwatershed 1 provides the greatest probabilities of use by 

unitype species associated with young forests, and the lowest probabilities of use by old-forest species and 

elk. Subwatershed 2 provides a higher probability of potential use by old-forest species, yet a low probability 

of use by elk and by young-forest species. Subwatershed 3 provides the greatest probability of use by elk, but 

a low probability of use by both young- and old-forest species.

Application of this method shows its potential utility in ranking the relative condition of subwatersheds for 

dissimilar wildlife guilds. Such a tool, if validated by research, could provide managers with a new approach 

for managing for multiple species of wildlife. Specifically, it could be used to design patch size, amount, and 

arrangement to accommodate the needs of various wildlife guilds at the subwatershed scale. This method 

also could be useful for analyzing cumulative effects of timber sales and other silvicultural treatments within 

and among subwatersheds.

At the subwatershed scale, this method accounts for the effects of amount, arrangement, size, and, to a 

limited degree, connectivity of patches. It does so by estimating the area within various distance bands 

away from meaningful edge, by seral stage, for the entire subwatershed. This method is in contrast to other 

indices of habitat fragmentation that typically rely on estimating perimeter length in relation to interior area 

for specific patches (Harris and Silva-Lopez 1992), or on more abstruse indices of fractal dimensions or 

distributions of patch size (O’Neill and others 1988) that can be hard to relate to actual species’ responses. 

Using more complex indices of habitat patch patterns may be difficult in evaluating fragmentation effects for 

a variety of wildlife guilds across a myriad of patches that make up a subwatershed. Also, defining a habitat 

patch (from which perimeter and area measurements are obtained) is a tricky judgment. Finally, the distance-band tool has already been incorporated into software commonly used in National Forests of the Blue 

Mountains (Hitchcock and Ager 1992), although it remains to be empirically validated for species other than 

elk.

Legend 1

Band Young Mid Old

1-100 189.6 100.9 100.0

101-200 77.5 84.7 0.0

201-300 66.1 21.2 0.0

301-400 56.8 0.0 0.0

401-500 62.5 0.0 0.0

> 500 599.2 0.0 0.0

Total Acres 

1051.7 206.8 100.0 1358.5

Figure 1. Subwatershed 1: 1358 acres, of which 1052 acres are young forest, 206 mid-seral, and 100 old forest. Young is light shading. Mid-seral and old are dark shading. Acreage within distance bands away from edges is shown in Legend 1 above.
13

Legend 2

Band Young Mid Old

1-100 178.2 92.5 171.5

101-200 23.2 72.3 148.2

201-300 1.0 28.9 125.5

301-400 0.0 11.4 97.1

401-500 0.0 7.7 92.5

> 500 0.0 11.9 238.1

Total Acres 202.5 224.7 872.9

1300.1 15.6% 17.3% 67.1 %

Figure 2. Subwatershed 2: 1300 acres, of which 202 acres are young forest, 225 mid-seral, and 873 old forest. Young is light shading. Mid-seral and old are dark shading. Acreage within distance bands away from edges is shown in Legend 2 above.

Legend 3

Band Young Mid Old

1-100 614.2 242.3 344.5

101-200 233.5 100.2 152.9

201-300 65.6 28.4 62.0

301-400 24.3 6.7 6.7

401-500 5.7 0.0 0.0

> 500 0.0 0.5 38.2

Total Acres 943.2 378.1 604.3

1925.6 49.0% 19.6% 31.4%

Figure 3. Subwatershed 3: 1926 acres, of which 943 acres are young forest, 378 mid-seral, and 604 old forest. Young is light shading. Mid-seral and old are dark shading. Acreage within distance bands away from edges is shown in Legend 3 above.

Evaluating watersheds—Once probability distributions of potential use are estimated for a cluster of 

subwatersheds, trends may become evident for the watershed as a whole. One might detect such trends by 

assessing the number or percentage of subwatersheds that favor elk, young forest, or old forest species within 

a watershed. Connectivity of habitat for unitype guilds might also be assessed by identifying subwatersheds 

that appear to be “weak links” (low use probabilities) relative to surrounding subwatersheds.
14

Table 4—Relative probability distributions of elk and unitype species for the 3 subwatersheds shown 

in figures 1, 2 and 3

 - - - - - - - - - - Relative probability distribution [1] - - - - - - - - - -

 Site Elk Young forest Old forest

Subwatershed 1 (fig. 1) 0.39 0.64 0.05

Subwatershed 2 (fig. 2) 0.40 0.05 0.52

Subwatershed 3 (fig. 3) 0.74 0.19 0.18

[1) Calculations: Relative probability = [(area in distance band) x (probability distribution in distance band)] summed for all 

distance bands in all patches of a subwatershed.

To illustrate, consider a hypothetical watershed comprised of 10 subwatersheds (fig. 4); 5 favor elk or multitype guilds, 3 favor unitypes associated with young forest, and 2 favor unitypes that use old forests. Assessment of these spatial conditions might provide insight as to deficiencies and needs of particular guilds within 

a watershed. Such assessments would help managers identify opportunities for designing management goals 

to balance the needs for managing dissimilar species and guilds. This balancing could be done within and 

among subwatersheds and watersheds across an entire National Forest.

Habitat allocation for elk and unitype species—Which of the three landscapes in figures 1, 2, and 3 is 

best for wildlife? The answer depends on one’s objectives. Management that favors edge-associated species (fig. 3) does not provide optimal conditions for habitat-interior species that use large, unfragmented 

landscapes. Likewise, management solely aimed at minimizing fragmentation of old forests (fig. 2) does not 

provide optimal conditions for multitype species that use several vegetation seral stages and edges, or for 

unitypes that occur in unfragmented, young forests.

How should dissimilar needs be accommodated within a single landscape? What specifically should be the 

desired future conditions in such landscapes? The short answer is that a balance must be struck among competing interests. Balance can be achieved at the subwatershed and watershed scales through manipulating 

patch sizes and arrangements. At different times, too, a given area can serve to provide unfragmented and 

fragmented conditions.

Conceptually, such manipulation requires the following steps:

▪ providing large, well-connected patches of old forests (fig 2);

▪ providing large, well-connected patches of young forests (fig. 1);

Figure 4. Hypothetical watershed composed of 10 subwatersheds: 5 favor elk or multitype species, three favor young 

forest species, and 2 favor oldforests species.
15

▪ compromising the size and connectivity of both old and young forests as a trade-off to sustain each 

over time (fig. 5); and

▪ providing some habitat interspersion among old and young forests as an outcome of the compromise 

(fig. 5).

This same process can then be repeated at the scale of the watershed, and again at the scale of a District or 

Forest. Of course, the practicality of any such optimal pattern must be fitted to the ground with consideration 

for roads, geologic hazards, other existing land allocations, and other factors.

Also, there are other management considerations for a featured species like elk that might be compatible 

with the requirements of unitype species. For example, management to reduce elk vulnerability to harvest 

requires large, well-connected patches of mid-seral or old forests and low densities of roads (tables 1 and 2). 

Such a management strategy would favor old-forest species as well (table 2).

The outcome of a compromise strategy (fig. 5) meets less than the maximum possible habitat requisites of 

both multitype and unitype guilds. Moreover, such a strategy may not meet the individual needs of sensitive, 

threatened, or endangered species. This possibility points to the obvious: explicit goals must be set at subwatershed and watershed scales, for both single species and dissimilar wildlife guilds, for trade-offs evaluated 

among each, and for designs implemented that likely favor one or more species or guilds over others. Only 

then can current conditions and effects of proposed actions be judged against desired objectives.

Objectives do not have to specify the layout design of habitats within a landscape; instead, they could describe a range of probabilities of potential use of the landscape. In this way, descriptions of desired future 

conditions would be flexible enough to allow for various on-the-ground solutions, with a variety of specific 

schedules of activities in space and time to meet the stated objectives.

Although such an approach might account for management needs of multiple species and guilds, the needs 

of sensitive, threatened, and endangered species must be addressed first. Single-species management cannot 

be abandoned for the sake of guild or multispecies management when the goal is to achieve a more holistic, 

ecosystem approach of landscape designs for wildlife. Ecosystem management is thus not a substitute for 

species management. Rather, it is additive and complementary.

Recommendations—Like most forest ecosystems of North America, past management in the Blue Mountains appears to have favored elk and other multitype species through increasing fragmentation of disjunct 

seral stages. Current National Forest Land and Resource Management Plans (“Forest Plans”) could stand to 

address the needs of unitype species in a holistic manner, especially those associated with old forests. The 

amount of undisturbed old forest remaining in the Blue Mountains is scant and fragmented, as is true with 

late-successional and old-growth forests in western Oregon and Washington (Johnson and others 1991).

Figure 5. Hypothetical subwatershed of 1800 acres that would yield a 

probability distribution above 0.5 for old-forest species, and above 0.3 

for both young-forest species and elk.
16

This situation is exacerbated by the fact that landscapes of the Blue Mountains are naturally fragmented. 

Applying our method across multiple subwatersheds and watersheds of the Province would likely help identify conditions that favor multitype guilds over unitypes. We recommend that such an assessment be done to 

validate this premise. We also recommend that the validity of this method be tested through research. Both 

of these efforts in tandem would help provide new insights for managing wildlife from an ecosystem perspective.

Example 2: Managing for Sustainable Native Fish Faunas in Eastern 

Oregon and Washington 

In this example, we explore conditions and methods for managing multiple species of native fish in eastern 

Oregon and Washington. The premise is that managers of eastside forests should manage for native coldwater stenotherms, that is, fishes with very narrow physiological tolerances and that require the highest quality 

water.

Coldwater stenotherms are declining on the eastside because of landscape problems resulting from abusive 

land-use practices. These species include the most prized sport fishes of North America and are of great 

commercial and cultural value. We argue that management for these featured, threatened, endangered, 

and sensitive species, and other species having moderate to high risk of extirpation, will lead to maximum 

species diversity of all fishes within the catchment basin. This approach is consistent with the principles of 

sustained-ecosystem management and a coarse-filtered approach. To understand why this is true, a brief synopsis of the ecology of fishes in streams is needed. The following section summarizes information on stream 

ecology as it applies to riverine fishes (Bayley and Li 1992).

Stream reaches and fish distributions: theory—In general, streams can be subdivided into two major 

subsystems connected by a transition zone, which can be either abrupt or gradual. The upper zone is shaded, 

small, steep, swift, rocky, highly oxygenated, and cold. The fishes that live in this zone, the rhithron, are 

coldwater stenotherms with high metabolic rates. They feed on aquatic insect drift and benthic invertebrates. Terrestrial drift is especially important because the riparian canopy reduces primary productivity 

and herbivorous insects are few. The lower zone, the potamon, is large, exposed to sunlight, of low gradient, 

sluggish, composed of smaller substrates, lower in dissolved oxygen, and warm. Fishes inhabiting this zone 

are warmwater fishes with low metabolic rates, tolerant of anoxic conditions, and ones that feed on a wider 

array of food. Piscivory, herbivory, and detritus feeding are more prominent trophic modes in the potamon 

community. The transition zone between the rhithron and potamon is composed of a mixture of these types 

of fish assemblages as well as coolwater, transitional forms.

The number of fish species is greater downstream than upstream. Different assemblage patterns (species 

combinations) occur depending on the degree to which shifts in physical gradients are abrupt (Rahel and Hubert 1991). If change is gradual, the number of species increases downstream in an additive manner because 

the transition zone is wide and the coldwater and warmwater faunas tend to overlap. If change is abrupt, 

patterns of zonation occur because the transition zone is narrow and the two types of faunas are more segregated. Patterns of distribution can shift up or downstream depending on the quality and quantity of water.

Stream reaches and fish distributions: management implications—Warmwater species are more abundant 

than coldwater species and the extent of warmwater reaches far exceeds those that are cold. Therefore, extending the coldwater zone further downstream increases species diversity of the catchment basin as a whole, as 

well as promoting the numbers of sensitive (coldwater) species. Species diversity is often indexed by combining species richness and equitability (relative abundance) of individuals among species. Ironically, managing 

for species diversity alone can reduce species richness in reaches of the upper basin because the more diverse 

species, the warmwater fishes, are pushed further downstream. The catchment basin is the most appropriate 

scale to conduct management; however, because it can include the entire fish fauna, it is an ecosystem on which 

boundaries can be placed for management and evaluation purposes (Frissell and others 1986).
17

Adaptation of stream fishes to disturbance—Evidence suggests that stream fishes have adapted to recurring patterns of disturbance over evolutionary time (Bayley and Li 1992, Meffe 1984, Resh and others 1988). 

The fish fauna of the Pacific Northwest has not adapted well to the radical modifications to the ecosystem 

caused by human activity (Li and others 1987, Reeves and Sedell 1992, Wissmar and others 1993).

Among the more serious threats are introductions of alien species. Alien species change the rules governing 

species assemblage structure and impose new rules on land managers. Native species that compete with or 

are preyed upon by alien species may become more sensitive to activities such as logging, which increases 

sedimentation and temperatures and results in the loss of coarse woody debris that creates and maintains 

pools and riffles. However, most of the documentation that alien species outcompete or directly exclude native fish species is correlative. Further direct synecological, experimental studies are needed to better determine the extent to which native species may have declined because of introduced species.

Alien species often predominate in systems that are badly disturbed by humans. Such effects described by 

Elton (1958) hold true for aquatic systems (Li and Moyle, in press; Moyle 1976). For instance, introduced 

smallmouth bass (Micropterus dolomieui) are now recognized to be major predators of native chinook salmon (Oncorhynchus tshawytscha) (T. Poe, pers. comm.; Tabor and others, in press). Once, smallmouth bass 

might have been excluded from chinook rearing areas by cold water, but elevated water temperatures caused 

by human activity now permit smallmouth bass to reside in chinook salmon rearing habitat in the John Day 

Basin where in 20 years they have expanded their range 640 miles upstream.

Types of disturbances—When large woody debris falls into streams, the riparian forest provides raw 

materials for habitat creation and habitat structure for fishes (Gregory and others 1991). This structure buffers large floods by providing refuges for fishes. When riparian vegetation and the flood plain remain intact, 

floods create new habitats and redistribute structural and organic materials within the aquatic ecosystem. 

Otherwise, floods are destructive (Junk and others 1989, Gregory and others 1991). For example, clearcut 

logging can cause catastrophic landslides (Lamberti and others 1991), decreased nutrient retention of the 

stream (Lamberti and others 1989), and resistance of the fish fauna to catastrophic floods (Fausch and Bramblett 1991, Pearsons and others 1992). Reduction of the flood plain and riparian forests alters the hydrograph, 

elevates stream temperatures, increases the silt burden, reduces habitat complexity and availability, and 

increases frequencies of flash flooding on eastside landscapes. Summer low flow conditions for coldwater 

fishes are more harsh because of water diversions and changes in runoff patterns. Silt from logging operations reduces spawning grounds (Platts and others 1989) by suffocating fish eggs (Reiser and White 1988). 

Elevated water temperature from logging can increase summer temperatures, adversely change the forage 

base of fishes, and cause a decline of fish standing crops (Graynoth 1979). Reduction of the riparian canopy 

on eastside streams caused by livestock grazing causes similar problems. Elevated stream temperatures 

stress coldwater fishes while diminishing their prey base (Li and others, in press; Tait and others, in press). 

Destruction of riparian vegetation has reduced the capacity of eastside basins to buffer the fish fauna from 

flash floods (Pearsons and others 1992).

Theory of resilience of stream fishes to disturbances—Successional patterns of fish assemblages in 

streams are different from those of terrestrial organisms (Vannote and others 1980). Successional patterns in 

streams are spatial rather than temporal (Fisher 1983). Stream fishes, especially in the Pacific Northwest, are 

specialized inhabitants of specific environments: coldwater specialists, warmwater specialists, small stream 

forms, and big river forms (Bayley and Li 1992). Specialization for temporal stages of ecological succession 

are not observed (for example, pioneering species); instead, with changes in environmental conditions, the 

affected fauna relocates during recolonization and in response to periodic disturbances such as floods and 

droughts (Matthews 1986, Matthews and others 1988).

Fishes are exposed to profound changes in water quality and quantity over an annual cycle and exhibit strong 

patterns of seasonal movement (Junk and others 1989). Recurring disturbances act like a reset button on a 

computer. In streams providing refuges, habitats can be quickly recolonized and faunal elements restored in
18

a matter of months (Freeman and others 1988, Matthews 1986, Matthews and others 1988). But flood plains 

and riparian forests must remain intact; otherwise, recolonization will take decades.

Management implications of disturbances— Because one does not have to manage for different successional stages, managing for biodiversity in lotic ecosystems is different than in terrestrial ecosystems. To 

maintain biodiversity, all faunal elements should be present within the basin. For this example, managing for 

the most sensitive species—the cold-water fishes—should benefit the fauna as a whole.

To transplant or introduce alien species to lotic ecosystems is undesirable because, once established, they 

are extremely difficult to remove. Problems they create will further constrain human activities because the 

native fauna is often more sensitive to human-caused or natural changes in the physical environment than is 

an established alien fauna. For example, the range of habitats occupied by the eastern brook trout is increasingly limited in its native waters because of displacement by introduced salmonids (Fausch and White 1981, 

1986; Larson and Moore 1985). Alien salmonids dominate in areas where the habitat has been altered. To 

avoid this scenario in eastern Washington and Oregon, the most important factor is to preserve the functions 

of the riparian forests and the floodplain. Unnatural landscape disturbances must be minimized and human 

patterns of land use should mimic natural patterns of environmental variation whenever possible (Poff and 

Ward 1989, Resh and others 1988).

Sensitive fauna as indicators of forest health: background on river fishes of eastside forests—The 

species richness of fishes in a catchment basin reflects its zoogeographical history and the condition of its 

watershed (Bayley and Li 1992, Hocutt and Wiley 1986, Hynes 1975). Management can affect both factors. 

We can affect zoogeography by creating or eliminating barriers to dispersal and by introducing species. 

Watershed condition affects the composition of fishes from the available species pool because water flows 

downhill. Therefore, disturbances at the top of the watershed can affect the water quality and habitat availability in the catchment downstream.

Zoogeographical history reveals that fish taxa of the Pacific Northwest have been subjected to periodic, 

immense geological and climatic changes (McPhail and Lindsey 1986, Minkley and others 1986). These 

changes include the massive and periodic Bretz floods in the Columbia Basin, tectonic uplift, glaciation, and 

volcanism. The fauna of the lower Columbia Basin reflects these major geologic upheavals, in that the fauna 

are extremely well suited for dispersal and colonization over long distances (Li and others 1987). More than 

50 percent of the fishes can disperse through the sea (McPhail and Lindsey 1986). This capacity has been 

compromised now because few areas are sufficiently intact to generate needed dispersants to disturbed areas. The tributaries of the mid-Columbia are much harsher environments for salmonids than the lower basins 

(McPhail and Lindsey 1986, Mullen and others 1992); they are more subject to drought and high temperatures. The mean standing crops (2-3 g/m2

) of the Methow, Entiat, and Wenatchee rivers are among the lowest 

recorded for the western United States. River-wide means have not been determined for the John Day River, 

but standing crops in selected sites range from 0 to 15 g/m2

 (Li and others, in press), and we suspect that 

most reaches are at the low end of the range. The margined sculpin (Cottus marginatus) may be endemic and 

restricted to the cooler streams in the Blue Mountains of southeastern Washington and northeastern Oregon 

(McPhail and Lindsey 1986).

The northern third of the Columbia Basin was affected by glaciation, is mountainous, and is comprised of 

cold, high-gradient streams. The following fishes appear to be remnants of a preglacial, western, coldwater fauna: pygmy whitefish (Prosopium coulteri), lake chub (Couesius plumbeus), burbot (Lota lota), slimy 

sculpin (Cottus cognatus), and the bull trout (Salvelinus confluentus) (McPhail and Lindsey 1986). These 

fishes are scattered throughout the West in mountainous areas of relatively pristine conditions and appear to 

be confined to coldwater habitats.
19

Drainages of southeastern Oregon were subject to at least three major oscillating periods of desiccation 

and inundation during the late Miocene to the Pleistocene. The oscillations resulted in massive extinctions 

of lake-adapted forms and the relict distribution patterns of today. The surviving fauna of each dry period 

found refugia and “were poised to expand and recolonize areas during the next wet phase” (Minkley and 

others 1986). The problem is that the western fish fauna is on the verge of disappearing completely because 

of human activity (Mickley and others 1986, Minckley and Douglas 1991). Although small relict populations 

might be going extinct, the paleontological record certainly suggests that conservation meet biodiversity 

objectives.

Sensitive fauna as indicators of forest health: management implications—Eastside management should 

focus on the habitat requirements of coldwater native fishes, which will also benefit native warmwater fishes 

because water quality for the basin will improve. We hypothesize that the resiliency of a fish fauna to human 

disturbance of a catchment basin (for example, salvage logging, fire suppression, creation of logging roads 

and water diversions, grazing, and application of pesticides) is related inversely to the number of species:

▪ of threatened, endangered, and sensitive status;

▪ of special concern;

▪ with high or moderate risk of extirpation; and

▪ with localized distributions, represented in its fish communities.

This hypothesis is an extension of the Index of Biological Integrity proposed by Karr and others (1986). The 

distribution and abundance of coldwater fishes should be used as indicators of biological integrity for the 

drainage.

To assess the resiliency of fish faunas in catchment basins and the health of watersheds on various National 

Forests, we mapped the reported distributions of species found: east of the Pacific Crest Scenic Trail in 

National Forests in Oregon, Washington, or both states; and inside National Forests or up to 25 miles outside 

of National Forests (hereafter referred to as species associated with National Forests) (figs. 6 and 7, table 5). 

Species included in the maps belong to at least one of the following categories:

▪ threatened, endangered, or special concern species (Williams and others 1989);

▪ sensitive species of Oregon (threatened or endangered species, or species which might quality for 

threatened or endangered status in the future; Marshall and others 1992);

▪ salmonids of high or moderate risk of extinction (Nehlsen and others 1991);

▪ fish of limited distribution (found within less than 8400 kml in a state) and associated with National 

Forests; and

▪ other fish associated with National Forests.

Some of the fishes in these designations are unique populations at the level of subspecies, races, or stocks. 

The data were obtained from faunal guides, publications, and lists of the status of native fishes (Behnke 

1992, Currens and others 1990; Haas and McPhail 1991; Howell and Buchanan 1992; Knutson and others 

1992; Lee and others 1980; Marshall and others 1992; McPhail and Lindsey 1986; Minckley and others 1986; 

Mullen and others 1986,1992; Nelson 1968; Nehlsen and others 1991; Williams and others 1989; Wydowski 

and Whitney 1979).
20

Results show that threatened, endangered, or sensitive fish species occur on every National Forest in eastern 

Washington and Oregon. The total number of fish taxa that are threatened, endangered, species of special 

concern, species with localized distribution, or species with high or moderate risk of extirpation, is inversely 

proportional to the resilience of catchment basins in National Forests. The decreasing order in this resilience 

index of National Forests in eastern Oregon was: Malheur (3 fish taxa), Ochoco (3), Deschutes (4), Mount 

Hood (4), Umatilla (4), Wallowa-Whitman (5), Winema (10), and Fremont (11). Hence, natural or human 

disturbances to fish communities seem to have been most adverse in Fremont and Winema National Forests. 

The decreasing order in the resilience index of National Forests in eastern Washington was: Mount BakerSnoqualmie (2), Gifford Pinchot (3), Colville (4), Okanogan (4), Wenatchee (5), and Umatilla (6). These 

indices suggest an overall lower resilience for catchment basins in National Forests in Oregon than in Washington. When sensitive species listed by the State of Oregon were added to the resilience index, differences 

in relative order of resilience among catchment basins associated with National Forests in Oregon became 

more evident: Ochoco (4), Deschutes (5), Malheur (5), Mount Hood (6), Umatilla (7), Wallowa-Whitman (7), 

Winema (10), and Fremont (14). The State of Washington has not issued a list of sensitive species of fish.

Figure 6. Distribution of fish associated with National Forests east of the Cascade Range in Oregon. (See table 5 for key to species 

names.) Codes for National Forests are: DE = Deschutes, FRE = Fremont, MAL = Malheur, MH = Mount Hood, OC = Ochoco 

(MA = Maury Ranger District), UM = Umatilla, WI = Winema, and WW = Wallowa-Whitman.

Many species with localized distributions were exclusively associated with the Winema and Fremont National Forests. Some of these species were also classified as sensitive (figs. 6 and 7, table 5). The total number of 

species of fish, for all categories combined, associated with National Forests in eastern Oregon were: Wallowa-Whitman (23), Umatilla (20), Malheur (19), Fremont (18), Mount Hood (15), Winema (15), Ochoco (13), 

and Deschutes (11). In eastern Washington, these totals were: Wenatchee (21), Okanogan (18), Umatilla (16), 

Colville (12), Mount Baker-Snoqualmie (12), and Gifford Pinchot (11) (table 1).
21

Figure 7. Distribution of fish associated with National Forests east of the Cascade Range in Washington. (See 

table 5 for key to species names.) Codes for National Forests are: CO = Colville (KA = Kaniksu Ranger District), GP = Gifford Pinchot, OK = Okanaogan, SN = Mount Baker-Snoqualimie, UM = Umatilla, and WE = 

Wenatchee.

Example 3: Management for Species Closely Associated with OldGrowth Forests of the Pacific Northwest 

In this example, we summarize a recent evaluation of species viability conducted in the Pacific Northwest 

(Thomas and others 1993). Here, we discuss the methods used to conduct a viability risk analysis of species 

closely associated with late-successional and old-growth forests. This project was completed in response to 

a court order to evaluate potential effects on old-growth species of implementing a conservation strategy for 

the northern spotted owl on National Forests.

The evaluation had three phases: identifying plant and animal species closely associated with old-growth 

forests and components of old-growth forests; evaluating potential effects on long-term viability of each 

species, under planning alternatives presented in a previous environmental impact statement; and identifying 

mitigations for habitat management to help ensure a high likelihood that all affected species would not be 

extirpated from the National Forests as a result of management actions. The process also addressed scientific 

uncertainty and lack of information that could influence the outcome of the evaluations of species viability. 

As per the court order, the evaluations were qualitative, based on the best available scientific information and 

professional judgment, but were not quantitative analyses of population and habitat dynamics.

This evaluation extended far beyond previous assessments of old-growth species (Johnson and others 1991, 

Lehmkuhl and others 1991, Ruggiero and others 1991) by including consideration for plant and animal taxa. 

This approach was inspired by the evaluations of how spotted owl planning will also provide for other species as conducted by Anthony and others (1992) for the Draft Spotted Owl Recovery Plan.

Identifying old-growth species—The following process was used to identify species associated with oldgrowth forests of the Pacific Northwest. First, a long list was constructed of species that find optimal habitat 

conditions in mature or old-growth forests for one or more life needs. The long list drew from existing literature and included more than 1200 species.
22

Table 5—Native species of fish living in National Forests east of the Cascade Mountains in Oregon (OR), 

Washington (WA) or both. National Forests cited parenthetically have fish up to 25 miles outside forest 

limits. Status of fishes: E = endangered. T = threatened. SE = sensitive. SC = special concern. A = high risk of 

extinction. B = moderate risk of extinction. LD = limited distribution. Dashed line = not reported. (Species 

codes indicates the distribution of fish in figures 6 and 7.

 Species Scientific name National Forests

 code and status Oregon Washington

 1 Percopsis transmontana Umatilla —

 (Mt. Hood) (Gifford Pinchot, Umatilla, Wenatchee)

 2 Oncorhynchus mykiss ssp. All National Forests east of All National Forests east of

 OR: SC, SE, A B. WA: A, B the Cascade Mountains the Cascade Mountains

 3 Cottus cognatus — Wenatchee

 WA: LD — —

 4 Catostomus catastomus — Kaniksu

 5 Cottus bairdi ssp. Ochoco Snoqualmie, Wenatchee

 OR: SE, SC (Malheur, Maury, Umatilla) (Colville, Okanogan)

 6 Oncorhynchus clarki ssp. Wallowa-Whitman Colville, Umatilla

 OR: SC (Mt. Hood) —

 7 Acipenser transmontanus Wallowa-Whitman, Mt. Hood —

 WA: LO — (Umatilla)

 8 Oncorhynchus kisutch Mt. Hood Gifford Pinchot

 OR: SE, LD. WA: LD — —

 9 Lampertra tridentata Wallowa-Whitman, Umatilla Wenatchee

 OR: SE, SC. (Deschutes, Malheur, Fremont) (Umatilla)

 10 Oncorhynchus nerka Deschutes, Mt. Hood, Wallowa-Whitman Gifford Pinchot, Wenatchee

 OR: A, SC — (Colville, Okanogan)

 11 Oncorhynchus tshawytscha Wallowa-Whitman Gifford Pinchot, Okanogan, Umatilla

 OR: SE, A, B. WA: A, B (Malheur, Mt. Hood, Ochoco, Umatilla) Wenatchee

 12 Richardsonius balteatus Umatilla, Winema Snoqualmie, Wenatchee

 (Malheur, Wallowa-Whitman) (Gifford Pinchot, Okanogan)

 13 Rhinichthys falcatus — Wenatchee

 (Wallowa-Whitman) (Okanogan, Snoqualmie)

 14 Prosopium williamsoni Malheur, Deschutes Snoqualmie, Wenatchee

 (Mt. Hood, Umatilla, Wallowa-Whitman) (Gifford Pinchot, Okanogan)

 15 Lampetra ayresi Mt. Hood —

 WA: LD — (Gifford Pinchot)

 16 Cottus asper — Snoqualmie, Wenatchee

 — (Okanogan)

 17 Prosopium coulteri — —

 WA: LD — (Colville, Okanogan)

 18 Gasterosteus aculeatus — —

 — (Okanogan, Wenatchee, Snoqualmie)

 19 Catostomus colombianus Malheur Snoqualmie, Wenatchee

 (Ochoco, Umatilla, Wallowa-Whitman) (Colville, Okanogan, Umatilla)

 20 Catostomus macrocheilus Wallowa-Whitman, Malheur Wenatchee

 (Maury, Ochoco, Umatilla) (Okanogan, Umatilla)

 21 Catostomus platyrhynchus Malheur —

 (Ochoco, Wallowa-Whitman, Umatilla) (Gifford Pinchot, Snoqualmie, Umatilla)

 22 Rhinichthys osculus Malheur, Wallowa-Whitman, Umatilla Snoqualmie, Wenatchee

 (Ochoco) (Colville, Okanogan)

 23 Ptychocheilus oregonensis Malheur, Wallowa-Whitman Okanogan, Wenatchee

 (Ochoco, Umatilla) (Colville, Snoqualmie, Umatilla)

 24 Mylocheilus caurinus — Wenatchee

 — (Okanogan, Umatilla)

 25 Salvelinus confluentus Fremont, Umatilla, Wallowa-Whitman Wenatchee, Okanogan

 OR: SE, SC. WA: SC Winema (Deschutes, Mt. Hood, Malheur) Colville, Umatilla

 26 Acrocheilus alutaceus Malheur, Umatilla, Wallowa-Whitman Snoqualmie

 (Ochoco, Maury) (Colville, Okanogan, Umatilla)
23

Table 5—Native species of fish living in National Forests east of Cascade Mountains in Oregon (OR), 

Washington (WA) or both. National Forests cited parenthetically have fish up to 25 miles outside forest 

limits. Status of fishes: E = endangered. T = threatened. SE = sensitive. SC = special concern. A = high risk of 

extinction. B = moderate risk of extinction. LD = limited distribution. Dashed line = not reported. (Species 

codes indicates the distribution of fish in figures 6 and 7.

 Species Scientific name National Forests

 code and status Oregon Washington

 27 Cottus rhotheus Wallowa-Whitman (Deschutes, Okanogan, Wenatchee

 Mt. Hood, Malheur, Ochoco, Umatilla) (Colville)

 28 Lampetra richardsoni Malheur Snoqualmie

 (Ochoco) —

 29 Cottus confusus Deschutes, Wallowa-Whitman Gifford Pinchot, Wenatchee

 (Malheur, Umatilla) —

 30 Rhinichthys cataractae Malheur, Wallowa-Whitman Colville, Umatilla, Wenatchee

 OR: SE. WA: T (Deschutes, Mt. Hood, Ochoco, Umatilla) (Kaniksu, Snoqualmie)

 31 Cottus beldingi Malheur, Umatilla, (Maury, —

 Mt. Hood, Ochoco, Wallowa-Whitman) (Umatilla)

 32 Gila bicolor ssp. Deschutes, Winema, Fremont —

 OR: T, SC, SE. WA: LD (Malheur, Wallowa-Whitman) —

 33 Cottus marginatus — —

 OR: SE, LD. WA: LD (Umatilla) (Umatilla)

 34 Catostomus occidentalis Fremont —

 OR: SE, SC, LD — —

 35 Catostomus luxatus Winema —

 OR: LD (Fremont) —

 36 Lampetra similis Winema —

 OR: LD — —

 37 Cottus perplexus Deschutes, Mt. Hood, Winema Gifford Pinchot

 38 Cottus tenuis Fremont, Winema —

 OR: SC, LD — —

 39 Cottus princeps Winema —

 OR: LD (Fremont) —

 40 Gila coerulea Fremont, Winema —

 (Deschutes) —

 41 Lampetra lethophaga Fremont, Winema —

 OR: LO —

 42 Cottus klamathensis Fremont, Winema —

 OR: LD — —

 43 Catostomus rimiculus — —

 OR: SC (Winema) —

 44 Catostomus snyderi Fremont, Winema —

 OR: LD — —

 45 Chasmistes brevirostris Winema —

 OR: LD (Fremont)

 46 Catostomus warnerensis — —

 OR: E, LO (Fremont) —

 47 Hesperoleucus symmetricus

 mitrulus Fremont —

 OR: SE, LD —

 48 Cottus pitensis — —

 OR: LD, SE (Fremont) —

 49 Gila bicolor eurysoma — —

 OR; SC, LD, SE (Fremont) —

 50 Oncorhynchus clarki lewisi Malheur, Umatilla —

 Or: SE, LO (Wallowa-Whitman) —

 51 Oncorhynchus clarki clarki Mt. Hood —

 OR: SE, SC — —

 52 Gila bicolor oregonensis — —

 OR: SE, LD (Fremont) —
24

From this long list, a short list of species closely associated with old-growth forests or components (large 

snags, live trees, and down wood) was constructed based on a compilation of data on distribution, ecological 

attributes, and habitat studies of each species. A set of repeatable rules were developed by which each 

species was assessed for membership on the short list (Thomas and others 1993). Next, all species on the 

short list were evaluated for effects on viability resulting from each of the spotted owl planning alternatives, 

and mitigation options were identified for those species that ranked less than medium high in viability under 

the selected alternative. Five panels of species experts were convened to refine the short list and to assess 

viability and mitigations for plants and terrestrial vertebrates. Invertebrates were assessed through contracts 

with regional experts, and fish were evaluated with aid from a concurrent panel’s (PacFish) analysis of 

anadromous salmonids (USDA 1992). The short list eventually included 667 species evaluated in all or in 

portions of their range, or fish stocks (hereafter, “species or ranges”): 190 fungi, lichen, and nonvascular 

plants; 122 vascular plants; 149 invertebrates associated with old-growth and riparian habitats; 112 

anadromous salmonid fish stocks; 21 amphibians (no species of reptiles was identified as closely associated 

with old-growth forests); 38 birds; and 35 mammals.

Evaluation of potential viability effects—The expert panels evaluated the potential effects on 50-year 

viability of each species. They did so by ranking each combination of species and planning alternatives according to a five-class rank order scale depicting degree of protection (table 6). The 50-year time frame chosen for the evaluation models a harvest period for most old-growth forest on lands suitable for timber production in National Forests. From the viability rankings, each species was assigned to one of four categories 

of extirpation risk: high (viability rankings of medium low or low), medium (viability rankings of medium), 

low (viability rankings of high or medium high), and unknown (not enough scientific information available 

by which to judge potential effects on viability).

In combination with existing Forest Plan standards and guidelines, each species was rated for potential effects on viability under each spotted owl planning alternative. Results indicated that existing Forest Plans, 

in combination with the strategy selected in the previous environmental impact statement for conservation 

of spotted owl habitat, would protect some 280 species or ranges, or about one third of all species closely 

associated with old-growth forests. This strategy still leaves some 387 species or ranges at risk of extirpation 

on one or more National Forests.

Identification of mitigations—For these 387 species or ranges, additional mitigations for habitat management were developed to help ensure they would not become extirpated over a 50-year period. Cumulatively, 

these mitigations included recommended standards and guidelines, developed first for those species or species groups with the broadest distributions—in this case, for species of riparian habitats (with a focus on the 

112 stocks of at-risk anadromous salmonid fish) and for marbled murrelet (Brachyramphus marmoratus), a 

Federally listed threatened species. Mitigations for riparian habitat and for marbled murrelet habitat would 

also provide for an additional 42 species or ranges. Then, other mitigations were developed and added for the 

remaining species still at risk: rare and locally endemic species (17 species or ranges) and other upland forest 

matrix species (7 species or ranges). With the accumulation of all mitigation steps, habitat for some 459 species or ranges would be provided so as to avoid extirpation.

Species with no information—Scant or no scientific information is available for judging the viability effects on the residual 208 species. Of this total, 23 species would likely be afforded some (unknown) degree 

of protection based on their ecological similarity to other species that occupy habitats and ranges already 

provided in the mitigation steps above. The remaining 185 species were truly unknown, and protection for 

them could not be judged. They included 19 fungi (mushrooms), lichens, and nonvascular plants; 8 vascular 

plants; all 149 invertebrate species, which as a group are poorly known; and 9 mammals, all of which were 

species of bats. For these unknown species, and for some others only potentially protected, further inventories and scientific studies were strongly recommended.
25

Table 6—Five-class ranking scale used to assess viability of populations of species closely associated 

with old-growth forests in the Pacific Northwest under various planning alternatives (Source: Thomas 

and others 1993:264)

HIGH - There is a high likelihood that the population(s) of the species would stabilize in National Forests within 

the range of the northern spotted owl. This provides broad latitude for natural catastrophes and uncertainties in 

knowledge. The likelihood of widespread or complete extirpation is low.

MEDIUM. HIGH - There is a moderately high likelihood, somewhat better than 50/50, that the population(s) of 

the species would stabilize in National Forests within the range of the northern spotted owl. This provides limited 

latitude for natural catastrophes and uncertainties in knowledge. There is less than a 50/50 likelihood of widespread 

or complete extirpation.

MEDIUM - There is roughly a 50/50 likelihood that the population would stabilize, and a similar likelihood of 

widespread or complete extirpation in National Forests within the range of the northern spotted owl. This provides 

extremely limited latitude for natural catastrophes and uncertainties in knowledge.

MEDIUM LOW - There is less than a 50/50 likelihood that the population would stabilize, and greater than 50/50 

likelihood of widespread or complete extirpation in National Forests within the range of the northern spotted owl. 

This provides no latitude for natural catastrophes and uncertainties in knowledge.

LOW - It is highly unlikely that the species’ population would stabilize, and there is high likelihood of widespread 

or complete extirpation in National Forests within the range of the northern spotted owl. There is no latitude for 

natural catastrophes and uncertainties in knowledge.

Conclusions—This example demonstrates the feasibility of evaluating vast numbers of plant and animal 

species, and the need to consider the full array of species in a habitat planning program. Assessing all species avoids the problems related to using ecological indicator species, indicator guilds, or featured species 

in management planning. The investment in time, money, and personnel for this scale of venture, however, 

precludes its use in everyday management. Thus, information and databases, developed for this project, on 

ecological requirements of each species are being prepared for publication and general use (Thomas and others 1993), to avoid “set-up” costs associated with gathering such basic data for future assessments.

This example demonstrates the potential of multiple-species evaluations and planning. However, Thomas 

and others (1993) emphasized the need to treat these viability evaluations and proposed mitigations as preliminary management hypotheses needing further quantification, refinement, and testing. Still, this multiple 

species approach, even within these limits, is a big step toward ecosystem management.

DISCUSSION, CONCLUSIONS, AND 

RECOMMENDATIONS

Continued total reliance on a species-by-species approach to preserve biodiversity likely will fail because of 

inefficiency and economics, and the associated direct and opportunity costs (Thomas and others 1993:8).

The three examples chosen for this chapter highlight the vast differences in approaches possible for multiplespecies and ecosystem management. Each case presents unique solutions to different management needs. 

For species groups requiring conflicting habitat and landscape attributes—interior environments of habitat 

patches and species edges or several types of habitat patches—the elk habitat management example illustrated one approach to combining management direction. The fish habitat management example emphasized 

how to consider zoogeography, site history, geology, and habitat ecology of aquatic systems in developing 

optimal management regimes for cold-water fishes. Consideration of ecosystem processes will become a 

greater focus in species management over time. The old-growth species management example demonstrated 

that requirements of all species of a biotic community can indeed be considered; that effects on potential 

viability can be qualitatively judged to help identify species requiring additional management consideration; 
26

that new standards and guidelines for helping ensure long-term viability can be crafted to meet the needs of 

an entire biotic community; and that scientific uncertainty and unknowns can be directly factored into viability evaluations and management recommendations.

What is the need to evaluate species and habitats in such detail? If species extinctions and speciations (evolution of new species) occur naturally, do we need to concern ourselves with such in-depth analyses? Records 

indicate that natural extinctions occur typically over a much longer time (2 to 4 orders of magnitude longer) 

than the life of National Forest management plans. Local extinctions have occurred not at constant rates over 

recent geologic history, but rather in sporadic episodes, such as the local extinctions of many forest dwelling plant and animal species from the Mount St. Helens 1980 eruption and from the prehistoric floods of the 

Columbia River (McPhail and Lindsey 1986). Speciation occurs over even longer periods than the recent 

human induced global “extinction spasm,” about 3 to 5 orders of magnitude longer than the life of management plans.

Historical local and global extinctions of species are not a reasonable justification for accepting local extirpation of species resulting from management activities as natural events. Lynch (1989) investigated several 

modes of speciation. His results suggest that 71 percent of species extinctions through geologic time were 

due to one species evolving into several new forms and not due to irreparable loss to the lineage. Therefore, 

extinction is also the result of creative, generative processes in addition to degenerative, destructive ones. 

Extinction as an evolutionary process is often misperceived by laypersons as the end of a lineage. The accelerated loss of species resulting from recent human activities is clearly a separate and distinct phenomenon 

in geologic history.

The regulations implementing NFMA call for insuring viability of all native and desired nonnative species 

within each planning area (National Forest, 36 CFR 219.19). Given the present state-of-the-art, even predictions of effects, during 100 years—that result from implementing a relatively short-term, 10-year forest management plan-cannot begin to balance long-term speciation with short-term extirpation and local extinctions. 

But to rationalize local, management—caused extirpations by citing natural speciation is to submit to the 

tyranny of short-term decisions and to ignore the creative aspects of long-term evolution of new life forms. 

One of the three tenets of ecosystem management—conserving or restoring natural biodiversity—would be 

violated.

For many species, the question becomes: At what finest scales of space and time is it acceptable to allow 

local extirpations yet still maintain the population and species throughout the planning area, physiographic 

province, and region? The answer must vary according to several factors: degree of rarity of the species 

and its selected habitat(s), or of a unique habitat; mandates of policy and dint of an accepted recovery plan 

for threatened or endangered species; and ecological attributes of the species, such as its metapopulation 

dynamics, degree of vagility, dynamics of immigration and emigration, and degree of habitat and resource 

specificity. For example, clearcutting an old-growth stand eliminates habitat for brown creepers (Certhia 

americana) on that site, yet the local population may continue to survive throughout the subwatershed if 

other old-growth forest stands persist. On the other hand, the same clearcut stand might have been the only 

location of colonies of red tree voles (Arborimus longicaudus) in the subwatershed. We must also consider 

that, for featured species such as ungulate game species, disturbance is necessary for producing substrates, 

cover, or resources for some life needs, such as forage.

Another example is instructive for threatened species management: the recent controversy over protection of 

a small bird—the California gnatcatcher (Polioptila californica californica)—and protection of the highly 

fragmented coastal sage scrub of southern California. In this case, developers, conservationists, and government agencies are seeking a common solution to conserve the bird’s remaining ecosystem, only 10 percent 

of which remains, rather than seek litigation focused on protecting the species per se under the Endangered 

Species Act. One proposal has as its compromise the destruction of parts of the bird’s habitat under agreement by developers if adequate amounts of critical habitat are set aside elsewhere to sustain the bird and its 
27

ecosystem. In a coarse-filter approach, this plan would also provide for at least some of the habitat’s other 

associated species, avoiding future legal battles over other threatened or endangered species associated with 

the coastal sage scrub habitat. The concept of protecting habitat of multiple species is fast becoming the 

favored approach to avoid conflicts over single-species management (Reinhold 1993).

This approach fits well with one of the primary stated purposes of the Endangered Species Act: “...to provide 

a means whereby the ecosystems upon which endangered species and threatened species depend may be 

conserved...” (Endangered Species Act, Sec. 2(b)). The outcome of the case with the California gnatcatcher 

might determine how future maintenance and recovery planning for threatened and endangered species are 

handled on both private and public lands. Likewise, the Forest Service must decide how to interpret its legal 

mandates, such as the Endangered Species Act and the National Forest Management Act.

Another consideration in managing for featured species in an ecosystem context is meeting the needs of Native Americans. Management programs are culturally biased for species of high commodity and social value 

to Euro-Americans to the exclusion of those favored by Native Americans (Hunn 1990). For instance, suckers, mountain whitefish, lamprey, and redside shiners are commonly considered “trash” fish by Euro-American sportsfishers. These same species are considered food fishes by the Sahaptin peoples (Native Americans 

of the mid-Columbia Plateau) and are held in high regard. Sculpins and crayfish are considered sacred icons 

and are not to be harmed. Black tree lichen (Bryoria fremonti), pine nuts, acorns, huckleberry, camas roots, 

and other plants are prized food items. Historically, many armed conflicts arose because of the insensitivity 

of Euro-Americans to adverse land use impacts on camas. This can cause conflicts in management policy 

because Native Americans retain rights to resources on lands ceded to the Federal Government. These rights 

have the same legal standing as treaties between sovereign nations. In keeping with Forest Service policy, 

it is incumbent to manage Forest Service lands to ensure substantial and sustainable yields of resources 

deemed important to native peoples.

In the end, successful integration of species and ecosystem management lies in clearly defining specific 

objectives at several scales of time and space and in proactively integrating all objectives. Successful integration of objectives can only be achieved by following the three basic principles of ecosystem management: 

to maintain or restore biodiversity, to maintain long-term site productivity, and to maintain sustainability of 

natural resource production. All activities, plans, and projects should be weighed at local, provincial, and 

regional scales against these three principles.

ACKNOWLEDGMENTS

We thank Dan Bottom, Evelyn Bull, Bruce Coblentz, Ross Kiester, Willa Nehlsen, and Wally White, for information or for reviews of sections or all of the manuscript. Thanks, too, to Paul Hessburg and Rich Everett 

for an opportunity to develop and present these concepts. The principal architects behind the case examples 

for this paper were Michael Wisdom on elk management; Hiram Li and Gonzalo Castillo on eastside fish 

management; and Bruce Marcot on the assessments of old-growth species. We gratefully acknowledge the 

work of the entire Scientific Analysis Team (Thomas and others 1993) for developing the basis for the third 

example.
28

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GLOSSARY

Alien (or exotic) species—Species of fish or wildlife, deliberately or accidentally introduced in an 

ecosystem, which have become permanently established; alien species often, but not always, have 

undesirable effects on native species; called “non-native species” in National Forest Management Act 

regulations (36 CFS 219).

Anoxic—Devoid of oxygen.

Bretz floods—A series of catastrophic floods caused by the rupture of glacial dams approximately 19,000 to 

12,000 years ago; the energy released by these floods (about 380 cubic miles of water dropping 3700 feet 

in elevation) has been likened to the explosion of a hydrogen bomb every 36 minutes over a 10-day period.

Coarse-filter management—Conservation of land areas and representative habitats with the assumption 

that the needs of all associated species, communities, environments, and ecological processes will be met; 

compare with fine-filter management.

Connectivity (of habitats)—The linkage of similar but spatially separated vegetation stands (such as 

mature forests) by patches, corridors, or “stepping stones” of like vegetation across the landscape; also, 

the degree to which similar habitats are so linked.

Cumulative effects—The addition of effects (positive or negative) on achieving a forest management 

objective, such as maintaining the viability of a wildlife species, from forest management activities 

conducted outside the immediate project area or before the current project.

Cumulative effects analysis—The prediction of cumulative effects through modeling and analysis (see 

cumulative effects).

Detritus—Decaying organic matter.

Ecological indicator species—A species whose population size and trend is assumed to reflect population 

size and trend of other species associated with the same geographic area and habitats; one type of 

management indicator species (see management indicator species).

Ecosystem management—Conservation and use of natural resources that serves to maintain biological 

diversity, long-term site productivity, and sustainability of resource production and use; the new 

management paradigm on National Forests.

Ecotone—See habitat edge.

Exotic species—See alien species.

Edge—See habitat edge.

Featured species—A species of fish or wildlife for which specific management guidelines have been 

written.

Fine-filter management—Specific management for a single or a few species rather than broad management 

for a habitat or ecosystem (see coarse-filter management).
37

Flagship species—A highly charismatic species, typically a large-bodied mammal or bird, that is in some 

peril of extirpation and that can be managed so as to also provide habitats and resources for other species; 

compare with umbrella species.

Floodplain—The terrestrial environment subject to periodic flooding.

Forest health—As a specific condition, refers to a growing forest having many or all of its native species of 

plants and animals; as a management objective, refers to maintaining or restoring the capacity of a forest 

to achieve health.

Fragmentation—See habitat fragmentation.

Guild—A set of species that share a common habitat (such as old-growth forests), that use the same 

resources (such as foods), or that use resources in the same manner (such as mode of foraging).

Guild indicator—Alternate name for indicator guild (see indicator guild).

Habitat edge—The margin where two or more vegetation patches meet, such as the boundary of a clearcut 

next to a mature forest stand; also see habitat fragmentation.

Habitat fragmentation—The splitting and isolating of patches of habitat, typically forest cover (but could 

also apply to grass fields, shrub patches, and other habitats); habitat can be fragmented from natural 

conditions, such as thin or variable soils, or from forest management activities, such as clearcut logging.

Habitat interior species—See unitype species.

Harvestable surplus—The number of game animals or fish that can be removed from a population, 

typically for hunting or fishing, that will not cause the population to unduly decline; sustainable 

harvestable surplus is the number that can be removed every year or harvest season for an indefinite 

period of time.

Herbivory—Eating vegetation.

Hydrograph—A graph of water discharge versus time.

Indicator guild—A set of species sharing a common habitat or resource use characteristic, for which 

management guidelines can be directed; all species of an indicator guild are sometimes assumed—

erroneously—to respond identically to management activities and environmental conditions.

Indicator species—See management indicator species and ecological indicator species.

Lotic (ecosystem or environment)—Moving water environments such as streams and rivers.

Management indicator—An index or attribute of the landscape that can be quantified to simplify land 

management planning to determine the success of implementation of planning guidelines; one type of 

management indicator is the management indicator species.

Management indicator species—A species of fish or wildlife for which a set of management guidelines 

have been written, chosen for simplifying land management planning; one type of management indicator 

species is the ecological indicator species.
38

Mid-seral forest—See seral stage.

Multitype species—A wildlife species that uses and requires two or more kinds of habitats or successional 

stages.

Piscivory—Eating fish.

Population viability—The likelihood of continued existence of well-distributed populations of a species 

throughout National Forests for a specified period of time; for example, high population viability connotes 

a high likelihood of continued existence of well-distributed populations throughout at least their current 

range on National Forests for a century or longer.

Potamon—Fishes that live in the lower, warm water, sluggish zone of stream systems; compare with 

rhithron.

Relict populations—Organisms once distributed broadly but now confined to remnant habitats over the 

landscape.

Rhithron—Fishes that live in the upper, cold water, swift zone of stream systems; rhithron are cold-water 

stenotherms (see stenotherm); compare with potamon.

Riparian habitat (or vegetation)—Vegetation associated with edges of, and directly influenced by, streams, 

rivers, ponds, lakes, and other water bodies.

Seral stage—The developmental or growth phase of a forest stand with characteristic structure and plant 

species composition; typically, young-seral forest refers to seedling or sapling growth stages; midseral 

forest refers to pole or medium sawtimber growth stages; and old or old-seral forests refers to mature and 

old-growth stages.

Sere—The entire set of all developmental or growth phases of a forest stand; each developmental phase is a 

seral stage (see seral stage).

Species-habitat matrix (or matrices)—A table, book, or data base depicting the relative quality of 

vegetation associations and seral stages for meeting various life needs of wildlife species, typically for 

reproduction, feeding, and resting or cover.

Stenotherm—Fishes with very narrow physiological tolerances to temperature.

Subwatershed—Portions of watersheds (see watershed) defined for management purposes; in the Blue 

Mountains of eastern Washington and Oregon, subwatersheds typically range from 1,000 to 10,000 acres.

Succession—The orderly and predictable development of vegetation on a site dominated first by grasses 

and forbs, then by shrubs, then by trees; typically follows stand-replacing disturbances such as clearcut 

logging or other regeneration timber harvests, or crown fires; see sere and seral stage.

Successional stage—See seral stage.

Sustainable harvestable surplus—See harvestable surplus.
39

Umbrella species—A large-bodied, popular species having a large home range and broad requirements 

for habitats and resources, that can be managed to also provide habitats and resources for other species; 

similar to flagship species.

Unitype species—A wildlife species that uses and requires only one kind of habitat or successional stage, 

typically their interiors.

Viability—See population viability.

Watershed—The entire drainage area of a river and its tributaries; in the Blue Mountains of eastern 

Washington and Oregon, watersheds typically range from 10,000 to 50,000 acres or larger.

Wildlife-habitat relationships program—A management program under the Fish, Wildlife, and Botany 

Units of USDA Forest Service that develops and applies scientific information on species-habitat 

relationships for managing habitats; an analogous program deals with fish-habitat relationships.

Windthrow—Trees blown over by the wind.

Young-seral forest—See seral stage.

Zoogeography—The study of the evolutionary history and prehistoric and current distributions of animals.



Marcot, Bruce G.; Wisdom, Michael J.; LI, Hiram W.; Castillo, Gonzalo C. 1994.

Managing for featured, threatened, endangered, and sensitive species and unique 

habitats for ecosystem sustainability. Gen. Tech. Rep. PNW-GTR-329. Portland, 

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station. 39 p. (Everett, Richard L., assessment team leader; Eastside forest ecosystem health assessment; Hessburg, Paul F., science team leader and tech. ed., 

Volume III: assessment).

The traditional approach to wildlife management has focused on single specieshistorically game species and more recently threatened and endangered species. Newer 

approaches to managing for multiple species and biological diversity include managing 

coarse filters, ecological indicator species, indicator guilds, and use of species-habitat 

matrices. Such modeling approaches each have strong as well as weak points, including conflicts among objectives for species with disparate needs. We present three case 

examples of integrating management for single species with management for multiple 

species and ecosystems: managing elk habitat in the Blue Mountains of eastern Oregon; 

managing for sustainable native fish faunas in eastern Oregon and Washington; and 

managing plant and animal species closely associated with old-growth forests in the 

Pacific Northwest.

Keywords: Wildlife habitat, fish habitat, biodiversity, eastside, threatened species, endangered species, sensitive species, management indicator species, species planning.

The Forest Service of the U.S. Department of 

Agriculture is dedicated to the principal of multiple 

use management of the Nation’s forest resources 

for sustained yields of wood, water, forage, wildlife, 

and recreation. Through forestry research, cooperation with the States and private forest owners, and 

management of the National Forests and National 

Grasslands, it strives—as directed by Congress—

to provide increasingly greater service to a growing 

Nation.

The U.S. Department of Agriculture is an Equal Opportunity Employer. Applicants for all Department 

programs will be given equal consideration without 

regard to age, race, color, sex, religion, or national 

origin.

Pacific Northwest Research Station 

333 S.W. First Avenue 

P.O. Box 3890 

Portland, Oregon 97208-3890
U.S. Department of Agriculture

Pacific Northwest Research Station

333 S.W. First Avenue

P.O. Box 3890

Portland, OR 97208

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