Marcot, B. G., M. A. Castellano, J. A. Christy, L. K. Croft, J. F. Lehmkuhl, R. H. Naney, K. Nelson, C. G. Niwa, R. E. Rosentreter, R. E. Sandquist, B. C. Wales, and E. Zieroth.  1997.  Terrestrial ecology assessment.  Pp. 1497-1713 in:  T. M. Quigley and S. J. Arbelbide, ed.  An assessment of ecosystem components in the interior Columbia Basin and portions of the Klamath and Great Basins.  Volume III.  USDA Forest Service General Technical Report PNW-GTR-405.  USDA Forest Service Pacific Northwest Research Station, Portland, OR.  1713 pp.

EXECUTIVE SUMMARY - TERRESTRIAL ECOLOGY ASSESSMENT

Biodiversity Findings

A first-ever catalogue of biodiversity of the Basin revealed diverse communities of plants, invertebrates, and vertebrates.  However, many species groups are largely unstudied.  Over 43,000 species of macro-organisms are estimated to occur in the assessment area and 17,186 species are known to occur.  Micro-organisms, critical to ecosystem health and function, probably tally at least several hundred thousand species.  This biodiversity results from the wide variety of habitats, topographic conditions, and prehistoric events within the study area.  For this assessment we evaluated 14,028 species of macroorganisms and explicitly included 1,339 individual species and 143 species groups in a data base on species-environment relations.  We also identified 296 species (excluding fish) that are of particular interest to American Indian tribes.

Some 264 taxa (species, subspecies, or fish stocks) have Federal listing status (Table__).  Among non-fish taxa, these include 184 Category 2 Candidate, 31 Category 1 Candidate, 11 Endangered, and 6 Threatened taxa, and 1 Federally Proposed as Endangered taxon.  FS and BLM list 538 species (excluding fish) as sensitive.  Some of the threatened and endangered species and many of the additional species of potential conservation concern are dependent on environmental or habitat components not evaluated at the broad scale.

We do not project viability of species in this assessment.  Rather, this assessment sets the stage and provides base information such as distribution of species, habitats and key environmental correlates of species, and effects of management actions as a basis for subsequent viability evaluation.  Viability of species under various planning alternatives is presented in another
document.

Our work provides an ecosystem context for management and restoration of habitats and environments for terrestrial species and communities.  We provide a classification system for environmental correlates and for ecological functions of species and identify functional groups of species based on their ecological roles.  Although FS and BLM are primarily charged with habitat
management, knowledge of such ecological roles of species and dynamics of plant and animal communities provides a stronger knowledge base and ecological foundation for ecosystem management.  We discuss selection of bioindicators for monitoring environmental changes and for assessing problems of grassland deterioration and examine possible actions for mitigation and restoration.

Products from this assessment of greatest potential interest to land managers include:  (a) lists of habitats and associated species with greatest declines in area or distribution since historic times; (b) Species-Environment Relations (SER) databases listing species by habitats and ecological functions for use in determining potential effects of ecosystem management activities and in proactively crafting such activities to emphasize or restore specific habitats or functions; (c) development of over 520 GIS maps of species distribution and additional maps on areas of high biodiversity and species rarity and endemism; and (d) descriptions of key ecological roles of fungi, lichens, bryophytes, and invertebrates for maintaining ecosystem health, and long-term productivity and sustainable use of resources.

Species at Risk

We have developed a complete catalogue of all federally listed threatened, endangered, and candidate species.  The database also includes information on The Nature Conservancy and Heritage Program rare plant categories, and state- and agency-specific listing categories of all species.  We have provided summaries of conservation plans and useful management actions for federally listed species.

We also identify a number of additional taxa, especially plants and invertebrates, worthy of additional attention.  These include:  394 fungi species; 40 functional groups of lichen species; sundry types of microbiotic crusts (not classified); at least 400 apparently regionally rare bryophyte species; 280 individual vascular plant species and 82 rare plant communities;  144 rare and endemic invertebrates (gastropods and insects); and various vertebrates.  Among the vertebrates are the more aquatic-dwelling amphibians, reptiles susceptible to ground-disturbing management activities, and birds and mammals associated with habitats that are now scarce, declining, or increasingly fragmented including native grasslands, sagebrush, and old low- and mid-elevation forests.  Basic inventories are needed for many of these species to determine their true rarity.

We do not advocate a species-by-species approach to management of all such species at risk.  Many of the species on these lists can be assessed in groups.  Inventories, where desired, could aim at gathering information for many species simultaneously, and management guidelines could address their collective habitat and environmental requirements or locations of joint occurrence.

Species Environment Relationships

Native grasslands (Fescue bunchgrass, Agropyron bunchgrass), shrublands (big sagebrush), and old single-stratum and multi-strata stages of many forest types, especially lower montane ponderosa pine forests, have declined in total area and shifted in distribution since historic times.  Declines are on both federal and non-federal lands with most on non-federal land.  Many species of plants and allies, invertebrates, and vertebrates are associated with these types.  Vertebrate species associated with the decline of old-growth forests included primary cavity excavators and species with large home ranges.  Other vegetation types, including young successional stages of forests, conifer-encroached sagebrush, and disturbed riparian conditions, have increased in total area and distribution since historic times.

Major ecological functions of species are summarized from the SER data bases.  Understanding functions are critical to crafting appropriate ecosystem management guidelines; the fate of individual species is only one facet of terrestrial ecology conservation.  The major ecological functions we addressed were:  species contributing to major biomass; herbivory; nutrient cycling relations; interspecies relations; soil productivity; wood decomposition; and water quality.  Identifying such ecological functional groups of species may be more useful for management of federal lands in the assessment area than would attempting to identify individual keystone species.

Probably no vertebrate has become regionally extinct in historic times; information on other taxa is lacking.  Small-bodied, less widely-vagile species may be at greater risk of declines or local extirpations.  Edges of ranges are important for species conservation.  We identified, by using the SER Model, species closely associated with conditions affected by management including forest canopy, mistletoe brooms, dead parts of live trees, trees with exfoliated bark, snags, down wood, litter and duff, fire processes and insect outbreaks, recreation, roads, and trails.  This information may be useful for management to predict potential effects of activities and identify specific conditions for conservation of species functional groups.

Fungi--The fungal flora and the effects of management activities on fungi are poorly known.  Some species are important to recreational and commercial gatherers.  Many kinds of fungi occur, including species with narrow distributions, that fruit after fire, that fruit in dung, and that are mychorrhizal and saprophytic and thus depend on host plants.  Fungi conservation can include protection of type localities in small, site-specific mycological preserves and further study of biology and ecology of species.

Lichens--Lichens play key ecological roles in ecosystems.  These include contributing mass and nutrients to litter and duff, increasing canopy and soil moisture holding capacity, fixing atmospheric nitrogen, serving as food source for American Indians and animals, and acting as bioindicators for air quality.  The 736 lichen species were divided into 40 functional groups based on ecological relationships.  The groups occur on four main substrates: dead organic matter, corticate and decorticate wood, rock, and soil.  Lichens are major components of native rangelands and provide critical soil functions, but have been threatened from exotic grasses, increased fire frequency, conversion of rangelands, and livestock trampling.  Lichens are part of microbiotic crusts and are susceptible to damage from livestock grazing and trampling.  One lichen, Texosporium sancti-jacobi, is listed as a candidate (C2) species.  Providing clumps of old trees and uneven-aged stands for their legacy of lichens cna improve conservation of lichens.  Basic lichen surveys and studies of management effects are needed to supplement our current poor knowledge base.

Bryophytes--Most bryophytes have wide Arctic-alpine and boreal distributions.  Others are coastal and north Pacific or occur in arid environments as part of soil crusts.  Four taxa are endemic to the assessment area.  Eleven ecological groups of bryophytes were identified based on common use of substrates.  Changes in water quality affect aquatic submerged and wet-rock species.  Forest canopy openings often adversely affect mycorrhizal species associated with decaying wood and forest humus and duff.  Commercial collection of bryophytes may affect some of the humus and duff species.  Other species in bogs, fens, and other environments are poorly studied.  Dry soil species are critical to soil protection.  Many species, at least 400, may be regionally rare but may need inventory to better determine status, especially those in arid habitats, peatlands, floodplains, geothermal areas, and isolated canyons and on calcareous rocks, and mineralized deposits.  Bryophyte conservation can include training for identification, adding bryophyte identification to field vegetation plot data, and inventory of bryophytes in protected areas.

Vascular Plants--Vascular plants in the assessment area number at least 8000 species, which include at least 154 local or regional endemics.  The diversity is from complex biophysical environments along gradients of elevation, bedrock and soils, temperature, and moisture.  Native plant communities have declined significantly in the assessment area, prompting concerns about future conservation of rare species and rare plant communities.  Of particular concern are communities affected by grazing, introduction of exotic species, and timber harvesting.  Examples are bunchgrass grasslands of the Palouse region and low elevation cedar/hemlock old forests.  The sustained harvestability of some 205 plant taxa are of concern to American Indians.  Conservation measures can include monitoring rare species and plant communities; off-site collection of pollen, seeds, and rare plants; and protection of key areas of high species rarity, endemism, and diversity.

Invertebrates--No terrestrial invertebrate species is listed as Threatened, Endangered, or C1 Candidate (although 5 aquatic invertebrates are threatened or endangered).  Thirty-eight terrestrial invertebrates are C2 Candidate species.  The FS does not list any as sensitive whereas BLM lists 25 as sensitive.  Some 95 terrestrial mollusks would benefit from conservation attention singly or as groups; many of these are confined to calcareous substrates.  Invertebrates are critical components of many ecosystem functions including detritovory and nutrient cycling.  We identified 104 rare and endemic species that bear further watching.  Functional roles of invertebrates include:  detritovory and nutrient cycling; maintaining soil structure, chemistry, and productivity; wood decomposition; herbivory; pathogenic effects on other organisms as well as control of disease-causing organisms.  Invertebrates can make excellent bioindicators of soil and vegetation health.  Most arthropods are poorly known; many are unnamed.  Arthropod predators may control other invertebrate populations including some defoliator pests, and require a mix of habitat types, down wood, and vegetation substrates.  Invertebrate pollinators are critical to maintaining the flora.  In grasslands and forests, species groups, particularly herbivores, are important links in food webs and affect vegetation succession.  A few are agricultural or forestry pests.  Fire and changes in soil chemistry directly affect invertebrates, especially in range and forest conditions altered from historic structures.  Other concerns are mechanical and livestock compaction and mixing of soils.  Other activities potentially harmful to desirable invertebrates include overgrazing, some recreation, loss of sphagnum bogs, exotic plants or arthropods, and pesticide use.  Providing a diversity of habitats, maintaining soil structure and soil chemistry, and preventing or eradicating exotic species could enhance conservation of invertebrate species.

Vertebrates--Amphibians require water or moist environments, are susceptible to exotic species, and are associated more with substrates such as down wood or talus than with vegetation types or stages.  Amphibians transfer nutrients from aquatic to terrestrial environments, are prey for predators, and contribute major biomass in forest ecosystems.  Studies are needed to determine the effects of water quality changes, canopy closure, pesticides, livestock grazing, eutrophication, and ultraviolet radiation on amphibians and on their dispersal and distribution.  Distribution of reptiles is more closely associated with elevation, aspect, and substrate than with vegetation.  Reptiles are susceptible to dams, off-road vehicle use, loss of wetlands, livestock grazing, and fire suppression.  Better survey techniques for reptiles are needed.  Birds are susceptible to management-induced changes in vegetation, especially historic declines in old, single-stratum, interior ponderosa pine forests and grasslands dominated by Agropyron bunchgrass.  In particular, impacts to grasslands have caused declines in Columbian sharp-tailed grouse numbers.  Neotropical migrants would benefit from conservation and restoration of riparian, old forest, shrub-steppe, grassland, and juniper habitats.  Population or habitat declines of mammals include some bat species and predators.  Some 42 vertebrates are listed as endangered, threatened, or C2 candidate.  Few locations still contain all top predators.

Biogeography, Endemism, and Biodiversity

Broad-scale biogeography of species is poorly studied in the assessment area.  We identified some species closely associated with some of the 9 landform classes.  Distributions of local endemics can result from contracted ranges from habitat loss or extirpations, overall scarcity of suitable environments, or other factors.  Apparent peripheral, disjunct, and scattered distributions of some species may be an artifact of the location and size of the area of interest.  Species such as boreal owl appear as disjunct populations because of breaks in distributions of suitable environments or incomplete sampling; smaller and more isolated disjunct populations are likely more susceptible to local declines or extinctions.  Locally endemic species or subspecies often are highly habitat-specific, such as Coeur d'Alene salamander.  Most ERUs had at least some unique species although many species overlapped several ERUs.  Some species are closely associated with single biophysical factors, although many species are likely correlated with multiple factors.

We mapped centers of concentration of (1) species rarity and endemism and (2) high biodiversity.  Centers of concentration were mapped separately for plants and for animals.  Locations with several centers of concentration of the two types mentioned defined smaller "hot spots" for plants and animals combined (Map__).  We identified 12 hot spots of species rarity and endemism and 7 hot spots of high biodiversity.  Additional hot spots may be identified at finer levels of geographic resolution than we used in this project.  Hot spots included southwestern Oregon, the Snake River, the Columbia River Gorge, and desert steppe in central and southern Washington.

Maintenance of environmental conditions within these hot spots can be one aspect of a broader biodiversity conservation strategy.  Other aspects can address protecting type locations of rare fungi, lichens, bryophytes, and vascular plants; protecting unique plant communities; ex situ plant conservation measures; providing for plant and animal species associated with rare or declining vegetation communities, especially native grasslands, native shrublands, and old-growth forests; ensuring adequate habitat for plant and animal species of interest to American Indian tribes; and conserving locations still containing all top vertebrate carnivores.

Natural areas on Federal lands total 11.72 million hectares in 26 land allocation categories.  The size of existing natural areas might be suitable for supporting at least small populations of at least 70 percent of vertebrate species.  Natural areas of various kinds might be 'realigned' or enhanced to better coincide with hot spots of species rarity and endemism and hot spots of high biodiversity.  Criteria for selection of new natural areas might be based on consistent ecological themes.

Maintaining Ecological Integrity of Terrestrial Ecosystems

Our findings suggest some measures for helping to meet goals of maintaining ecological integrity of terrestrial ecosystems.

(1) To conserve biodiversity, some realignment of natural areas may better represent ecosystems and provide for rare and endemic species.  Also, conservation measures can be considered for at least 12 "hot spots" of species rarity, endemism, and richness.  The full array of historic vegetation conditions in the Basin can be provided.

(2) For maintaining long-term productivity of terrestrial ecosystems, the ecological roles of soil micro-organisms could be better studied and incorporated into management.  Also helpful would be providing environments for unique assemblages of species and functional groups of species.

(3) For maintaining long-term evolutionary potential, populations of species with disjunct distributions could be provided for, as well as populations of locally and regionally endemic species and locally endemic subspecies.  Protection could be afforded for type localities for rare plants.  Both in-field and off-site rare plant conservation measures could be instituted.

Additional work

Some policy questions and issues can not be addressed at the broad regional scale.  Additional work is necessary for (1) further describing historical trends and current conditions and threats for species at finer scales of resolution that this current study affords, and (2) collecting basic scientific knowledge on life history, ecology, and distribution of many species.

Much basic scientific information on species could be gathered through inventories of many fungi, lichens, bryophytes, and rare plants.  Selected rare plant communities could be monitored.  Basic inventories and taxonomy studies of invertebrates could be conducted, along with studies on basic ecology, biology, and ecological roles of many plants, most invertebrates.  Early warning indicators (bioindicators) of potentially degrading ecosystem health could be identified and used cost-effectively.  Potentially useful bioindicators include some soil crusts, microorganisms, arthropod herbivores, fungi, lichens, and bryophytes.

About 86% of arthropods, 67% of fungi, and 51% of mollusk species estimated to occur in the assessment area not have been studied, surveyed, or, in some cases, even identified.  Much inventory and basic systematics work remains to be done on these groups.  Soil microorganism groups and microbiotic (soil) crusts of the assessment area, although critical for maintaining soil productivity, are poorly known and little studied.