Invertebrates of the Columbia River Basin Assessment … of Life Sciences, FB 1056, Maharishi University of Management, Fairfield, IA 52557-0001; James Johnson is a professor and chair

United StatesDepartment ofAgriculture

Forest Service

Pacific NorthwestResearch Station

United StatesDepartment of the Interior

Bureau of LandManagement

General TechnicalReportPNW-GTR-512June 2001

Invertebrates of the ColumbiaRiver Basin Assessment Area

Christine G. Niwa, Roger E. Sandquist, Rod Crawford,Terrence J. Frest, Terry Griswold, Paul Hammond, ElaineIngham, Sam James, Edward J. Johannes, James Johnson,W.P. Kemp, James LaBonte, John D. Lattin, James McIver,Joel McMillin, Andy Moldenke, John Moser, Darrell Ross, TimSchowalter, Vince Tepedino, and Michael R. Wagner

AuthorsChristine G. Niwa is a research entomologist, U.S. Department of Agriculture, Forest Service, PacificNorthwest Research Station, Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR97331; Roger E. Sandquist is an entomologist, U.S. Department of Agriculture, Forest Service, PacificNorthwest Region, P.O. Box 3623, Portland, OR 97208-3623; Rod Crawford is Curator of Arachnids,Burke Museum, University of Washington, Box 353010, Seattle, WA 98195; Terrence J. Frest andEdward J. Johannes are malacologists, Deixis Consultants, 2517 NE 65th St., Seattle, WA 98115-7125;Terry Griswold is a research entomologist and curator, W.P. Kemp is a research leader, and VinceTepedino is a research entomologist, U.S. Department of Agriculture, Agricultural Research Service, BeeBiology and Systematics Laboratory, Utah State University, Logan, UT 84322; Paul Hammond is a re-search entomologist, John D. Lattin is a professor emeritus, Andy Moldenke is a research associate,Tim Schowalter is a professor, Department of Entomology, Elaine Ingham is an associate professor, De-partment of Botany and Plant Pathology, and Darrell Ross is an associate professor, Department of For-est Science, Oregon State University, Corvallis, OR 97331; Sam James is an associate professor, Depart-ment of Life Sciences, FB 1056, Maharishi University of Management, Fairfield, IA 52557-0001; JamesJohnson is a professor and chair of entomology, Department of Plant, Soil and Entomological Sciences,University of Idaho, Moscow, ID 83844-2339; James LaBonte is an insect program specialist, OregonDepartment of Agriculture, 635 Capitol St. NE, Salem, OR 97301-2532; James McIver is an ecologist,U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Forestry and RangeSciences Laboratory, 1401 Gekeler Lane, La Grande, OR 97850; Joel McMillin is an entomologist,Rapid City Service Center, U.S. Department of Agriculture, Forest Service, 803 Soo San Drive, RapidCity, SD 57702-3142; John Moser is a research entomologist emeritus, U.S. Department of Agriculture,Forest Service, Southern Research Station, Alexandria Forestry Center, 2500 Shreveport Hwy., Pineville,LA 71360; Michael R. Wagner is a regents professor, School of Forestry, Northern Arizona University,Box 15018, Flagstaff, AZ 86011.

Invertebrates of the Columbia River BasinAssessment Area

Christine G. Niwa, Roger E. Sandquist, Rod Crawford, Terrence J.Frest, Terry Griswold, Paul Hammond, Elaine Ingham, Sam James,Edward J. Johannes, James Johnson, W.P. Kemp, James LaBonte,John D. Lattin, James McIver, Joel McMillin, Andy Moldenke, JohnMoser, Darrell Ross, Tim Schowalter, Vince Tepedino, and MichaelR. Wagner

Interior Columbia Basin Ecosystem ManagementProject: Scientific Assessment

Thomas M. Quigley, Editor

U.S. Department of AgricultureForest ServicePacific Northwest Research StationPortland, OregonGeneral Technical Report PNW-GTR-512June 2001

PrefaceThe Interior Columbia Basin Ecosystem Management Project was initiated by the Forest Service and theBureau of Land Management to respond to several critical issues including, but not limited to, forest andrangeland health, anadromous fish concerns, terrestrial species viability concerns, and the recent declinein traditional commodity flows. The charter given to the project was to develop a scientifically sound,ecosystem-based strategy for managing the lands of the interior Columbia River basin administered bythe Forest Service and the Bureau of Land Management. The Science Integration Team was organizedto develop a framework for ecosystem management, an assessment of the socioeconomic and biophysi-cal systems in the basin, and an evaluation of alternative management strategies. This paper is one in aseries of papers developed as background material for the framework, assessment, or evaluation of alter-natives. It provides more detail than was possible to disclose directly in the primary documents.

The Science Integration Team, although organized functionally, worked hard at integrating the approach-es, analyses, and conclusions. It is the collective effort of team members that provides depth and under-standing to the work of the project. The Science Integration Team leadership included deputy teamleaders Russel Graham and Sylvia Arbelbide; landscape ecology—Wendel Hann, Paul Hessburg, andMark Jensen; aquatic—Jim Sedell, Kris Lee, Danny Lee, Jack Williams, Lynn Decker; economic—Richard Haynes, Amy Horne, and Nick Reyna; social science—Jim Burchfield, Steve McCool, JonBumstead, and Stewart Allen; terrestrial—Bruce Marcot, Kurt Nelson, John Lehmkuhl, RichardHolthausen, and Randy Hickenbottom; spatial analysis—Becky Gravenmier, John Steffenson, andAndy Wilson.

Thomas M. QuigleyEditor

United StatesDepartment ofAgriculture

Forest Service

United StatesDepartment ofthe Interior

Bureau of LandManagement

Interior ColumbiaBasin EcosystemManagement Project

AbstractNiwa, Christine G.; Sandquist, Roger E.; Crawford, Rod [and others]. 2001. Invertebrates of the

Columbia River basin assessment area. Gen. Tech. Rep. PNW-GTR-512. Portland, OR: U.S.Department of Agriculture, Forest Service, Pacific Northwest Research Station. 74 p. (Quigley,Thomas M., ed.; Interior Columbia Basin Ecosystem Management Project: scientific assessment).

A general background on functional groups of invertebrates in the Columbia River basin and how theyaffect sustainability and productivity of their ecological communities is presented. The functional groupsinclude detritivores, predators, pollinators, and grassland and forest herbivores. Invertebrate biodiversityand species of conservation interest are discussed. Effects of management practices on wildlands andsuggestions to mitigate them are presented. Recommendations for further research and monitoring aregiven.

Keywords: Nutrient cycling, detritivory, predation, pollination, herbivory, bacteria, fungi, nematodes(roundworms), arachnids (spiders and scorpions), insects, gastropods (snails and slugs), oligochaetes(earthworms), invertebrate biodiversity.

Contents1 Introduction

1 Ecological, Economic, and Scientific Importance of Invertebrates

2 Methods

3 Interior Columbia Basin Ecosystem Management Project

3 Functional Groups of Invertebrates

3 Detritivores and Nutrient Cycling

8 Predators

11 Pollinators

14 Grassland Herbivores

16 Forest Herbivores

24 Invertebrate Biodiversity

25 Approaches to Managing Invertebrate Biodiversity

28 Towards an Approach for Conservation of Invertebrates

28 Invertebrate Species of Conservation Interest

28 Rare or Sensitive Invertebrate Species

35 Unique Habitats for Invertebrates

36 Managing to Retain Invertebrates and Their Ecological Functions

37 Compositional and Structural Diversity

37 Soil Structure and Chemistry

37 Exotic Organisms

38 Invertebrate Research and Monitoring Priorities

38 Research Emphasis

40 Monitoring Emphasis

40 Conclusions

41 Focus on Key Functional Groups

41 Preserve Key Habitats

41 Take Care in Management

41 Broaden the Scope of Investigations

42 Practice Adaptive Management

43 Acknowledgments

44 References

58 Appendix 1

60 Appendix 2

65 Appendix 3

74 Appendix 4

1

IntroductionEcological, Economic, and ScientificImportance of InvertebratesInvertebrates other than pest insects and diseaseorganisms have received little consideration inmost planning efforts (FEMAT 1993, Gast andothers 1991, Hessburg and others 1994, Samways1994). Ginsberg (1993) lists five reasons to beinterested in the status of invertebrates.

1. Invertebrates are found in most ecosystems,worldwide. Insects and other invertebrates consti-tute most of the biosphere faunal biomass. Forexample, in a hectare of tropical rain forest inManaus in the Brazilian Amazon, there are about1 billion invertebrates, mostly mites and springtails.This constitutes about 93 percent of the 200 kilo-grams of total dry weight biomass of all animalspresent (Wilson 1987).

2. Invertebrates drive ecosystem processes. Inver-tebrates are vital to energy and nutrient processingand cycling in ecosystems. All but primary produc-ers are found at all trophic levels, and because oftheir abundance and diverse habitats, they play amajor role in nutrient flow through ecosystems.They are important both as consumers (herbi-vores, detritivores, and predators) and as second-ary producers (prey). The importance of herbivo-rous insects in forest and range systems, forexample, is appreciated. Decomposers, however,often are overlooked. A square meter of NorthAmerican pasture soil (to a depth of 15 centime-ters), for example, yielded about 43,100 mites and119,800 springtails (Anderson 1975, Salt and oth-ers 1948). Gastropod densities ranging between1.5 and 4.5 million per acre have been reported fortemperate habitats in the grassland to forest spec-trum (Solem 1974). Pacific Northwest forest soilaverages over 200 species and 250,000 individualarthropods per square meter (Moldenke 1990,1999). Decomposers are vital to the nutrient cy-cling process and other ecosystem functions. Nev-ertheless, some of the soil and litter arthropods re-main undescribed (Schaefer and Kosztarab 1991).

3. Invertebrates have unique value for scientificstudy, assessment, and monitoring. Invertebratesare ideal study organisms because there are manyspecies represented by large populations and di-verse habitats, with short generation times andrapid population growth, and they provide a fine-grain representation of the system. Invertebratesare amenable to experiments because of their di-verse life history patterns, generation times, repro-ductive strategies, trophic roles, and behavior.Thus, invertebrates offer great potential for re-search and monitoring within an adaptive manage-ment context. Short generation times and highreproductive potential also make invertebratesexcellent indicator and “early warning” organisms.A sudden reduction in population could be indica-tive of environmental changes such as chemicalcontamination, disease, drought, or overpredation.Longer lived, less diverse organisms or plantsmight not display obvious effects of subtle envi-ronmental perturbations for years or even decades.Much literature addresses the use of invertebratesas indicators of water quality and wetland condi-tions (Plafkin and others 1989).

Invertebrates are well suited for monitoring therecovery of ecosystems after large-scale perturba-tions such as the fires at Yellowstone NationalPark (Christiansen and others 1992, Pilmore 1996)and Hurricane Andrew at Everglades NationalPark. After a serious disturbance where a habitathas been altered (e.g., burned, covered with volca-nic ash, bulldozed, or flooded), many inverte-brates, because of their high dispersal rates viawind, water, and macrofauna, are generally thefirst animals to colonize an area. They changemicrohabitats, spread seeds, modify soils, andotherwise initiate processes to reestablish viablehabitats for other taxa. Each stage in the develop-ment and succession of an ecosystem has its owngroup of invertebrates altering the habitat andpaving the way for later successional stages(Brown 1982, Southwood and others 1979).

Taxonomic and faunistic data on invertebrates arealso vital to long-term ecological studies, as dem-onstrated by the National Science Foundation’sLong Term Ecological Research Program (CEQ1985, Parsons and others 1991).

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4. Invertebrates have important economic signifi-cance. Invertebrates affect human welfare in bothpositive and negative ways by their influence onagriculture, forestry, and industry. They are impor-tant in soil development, pollination of crops andwildland plants, and controlling important pestspecies. They serve as food items on a worldwidescale (for example, shrimp, lobsters, crabs, clams,scallops, and squid; in many parts of the world,various insects serve as dietary staples).

Invertebrates also can be destructive to crops anddomestic animals. Great effort is devoted to mini-mizing pest damage and detecting nonnative pests.Effective biological control (involving introduction,release, and establishment of alien biological con-trol agents) with minimal negative environmentaleffect, also requires faunal data on invertebrates inthe region where pest management is conducted(Kim and Knutson 1986) to avoid greater environ-mental perturbances.

5. Invertebrates profoundly affect public health.Invertebrates serve as vectors and reservoirs fordiseases having major effects on human popula-tions. For example, plague (caused by a bacteriumtransmitted by fleas), Lyme disease and RockyMountain spotted fever (transmitted by ticks), andarboviral encephalitides (viral diseases transmittedby mosquitoes) pose threats to human and animalhealth. Invertebrate diversity data, along with geo-graphic, geologic, biological, and social factors, areimportant to zoonotic research in identifying po-tential vectors and reservoirs and in predictingpossible epidemics (Heyneman 1984).

Given the major contribution of invertebrates toglobal biodiversity and their importance both tonatural systems and directly to humans, placingmore attention in wildland management on inverte-brates is critical to achieving long-term manage-ment goals. Any mandate for managing ecosys-tems in a sustainable manner contributes to inver-tebrate conservation. Management actions haveimportant implications for invertebrate taxa to beconsidered when developing ecosystem manage-ment programs.

MethodsThe large number of invertebrate species in somemajor groups precludes a species-specific treat-ment. Instead, in this report, invertebrates are dis-cussed as functional groups, and individual speciesare addressed only as examples of a much largerbiota. Not all groups are equally addressed becauseof the difficulty of getting all the information at asimilar level of detail.

This report summarizes information derived fromseveral sources. The primary sources were con-tract reports prepared by taxon or subject matterspecialists and ideas and information gatheredfrom panels of experts, some of whom are coau-thors of this report. The lead authors of this reportextracted and summarized information from thesesources and synthesized the information into aformat more accessible to wildland managers andgeneral biologists. This report emphasizes the im-portance of invertebrates in the wildlands of theColumbia River basin (hereafter referred to as thebasin assessment area) east of the crest of theCascade Range including portions of the Klamathand Great Basins in Oregon.

Several science panels met to consider the effectsof management practices on terrestrial inverte-brates and their ecological functions. Mitigationmeasures were noted as well as needs for researchand monitoring. Research and monitoring werediscussed in the context of providing useful infor-mation on priority management issues to landmanagers. Appendix 1 lists participants in the paneldiscussions.

Each panelist was given a list (appendix 2) ofpotential management practices. After discussion,a shorter list of issues relating to these practiceswas developed. These issues were discussed foreach of the taxonomic or functional groups. Ef-fects of these issues on terrestrial invertebratesand their ecologic functions, mitigation measures,and opportunities for research and monitoringwere noted.

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Interior Columbia Basin EcosystemManagement ProjectThis report provides general background on theinvertebrates of the basin assessment area andhow they affect sustainability and productivity oftheir ecological communities. It was used by theInterior Columbia Basin Ecosystem ManagementProject to assess the terrestrial ecology of thebasin assessment area (Marcot and others 1997).The assessment describes prehistoric, historical,and current conditions and trends in terrestrialenvironments, selected individual species (plants,fungi, bryophytes, lichens, invertebrates, andvertebrates), species groups, ecological commu-nities, and terrestrial ecosystems.

Other assessments included aquatic resources,landscape ecology, economics, and social sciences.All assessments, including terrestrial ecology, weresummarized in Quigley and Arbelbide (1997).Quigley and others (1996) examines the condit-ions of the basin assessment area by integrating theinformation brought forward through an examina-tion of current conditions compared with broadsocietal goals.

This document provides information for publicdiscussion about conditions, trends, and potentialoutcomes associated with management of thenatural resources of the basin assessment area.Effects of wildland management practices by theUSDA Forest Service (FS) and USDI Bureau ofLand Management (BLM) are reviewed. Generalsuggestions that may help to mitigate harmfuleffects are presented. Recommendations forfurther research and monitoring also are given.

Functional Groups ofInvertebratesWhat are the important roles of invertebrates inthe basin assessment area? Several primary eco-system functions were chosen to illustrate theroles of invertebrates. Not all functions are pre-sented because resources were insufficient tocover all taxa.

In the following sections on functional groups,specific examples of management practices andtheir effects on biodiversity or ecological functionare addressed. Information about the effects ofmanagement practices on invertebrates mostly isknown but limited for specific locations. To betterunderstand the effects of management, it is sug-gested that the professional judgement of special-ists be considered as working hypotheses that canbe tested.

Detritivores and Nutrient CyclingIn the past, soil has been perceived as inert andinanimate, and soil properties as distinctive butrelatively unchanging. Faunal constituents, untilrecently, have been largely ignored in managementactivities. Soil microbes also have been ignored,except for a few high-profile organisms such assoilborne pathogens and certain mycorrhizal fungiand nitrogen (N)-fixing bacteria (Harvey andothers 1994).

Studies indicate soil functions as a communityof interacting organisms ranging from viruses andbacteria, fungi, nematodes, mollusks (especiallyslugs and microgastropods) and arthropods tomammals and other vertebrates. Microbial biomassalone can reach 10,000 kilograms per hectare inproductive, inland Western forest soils (Harveyand others 1994). Combined, activities of all theseorganisms are responsible for developing the criti-cal properties that underlie fundamental soil fertili-ty, health, and productivity. Biologically drivenproperties resulting from such complex interactionsrequire from only a few to several hundred yearsto develop (Harvey and others 1994). The greaterthe number of interactions of decomposers, theirpredators, and the predators of those predators,the fewer the losses of nutrients from that system(Harvey and others 1994).

Insects1—Wood-feeding insects are instrumentalin the decomposition and mineralization ofcoarse woody debris. Secondary bark beetles(also primary, or tree-killing, bark beetles) pene-trate the bark of recently dead trees and inoculatewood with, and provide access to, saprophytic

1 This section is based primarily on Schowalter (1995).

4

micro-organisms. They also provide attractivevolatile chemicals, habitats, and resources forother invertebrates (such as fungivores and ter-mites), thereby accelerating decomposition(Schowalter 1995, Schowalter and others 1992,Stephen and others 1993).

Ambrosia beetles, including Platypus wilsoniSwaine (Platypodidae), Trypodendron spp.,Gnathotrichus spp., and Xyleborinus saxeseni(Ratzeburg) (Scolytidae), initiate penetrationof sapwood. These beetles inoculate gallerieswith mutualistic fungi (Ambrosiella spp.,Ceratocystiopsis spp.), which the beetles culti-vate (by removing other competing fungi) andeat. Studies (Moser and others 1995, Schowalterand others 1992, Zhong and Schowalter 1989)indicate these insects regulate the initial decom-poser assemblage in the sapwood and therebyaffect initial decomposition patterns.

Termites and other wood-boring beetles and waspsexcavate large N-rich galleries in wood in concertwith N-fixing and cellulytic gut symbionts. Theyincrease wood aeration and the surface area ex-posed to decomposers, thereby facilitating decom-position and enriching surrounding soils that areoften N-impoverished (Salick and others 1983,Slaytor and Chappell 1994, Waller and others1989). Principal termites occurring throughout thebasin assessment area include Zootermopsis ne-vadensis (Hagen) (dampwood termite) and Reticu-litermes spp. (tibialis Banks and hesperusBanks—aridland subterranean termite). Zooter-mopsis is associated primarily with mesic forests,whereas Reticulitermes occupies drier habitats.

Carpenter ants (Camponotus spp.) and Formicaspecies also excavate large galleries in wood andincrease wood aeration and surface area exposedto decomposers (Harmon and others 1986,Youngs 1983). In addition, some of these ants aremajor regulators of canopy communities by tend-ing aphids and preying on defoliators. They aremajor food resources for woodpeckers, includingthe pileated woodpecker (Dryocopus pileatus)(Torgersen and Bull 1995).

Termites and carpenter ants also provide thesocial structure that supports diverse assemblagesof termitophilous and myrmecophilous invertebratespecies. Many of these invertebrates are highlyspecialized to mimic their hosts and intercept foodshared among colony members (tro-phallaxis).Clearly, these species are dependent on the abun-dance and distribution of the host termites or ants.

Other arthropods such as millipedes, sowbugs,and oribatid mites consume and shred (commi-nute) large quantities of dead leaves and needles inforest litter and inoculate microbes into largerdetrital surface area. This fragmentation makesnutrients more readily available to microbes thatcontinue the cycling process. Without the crushed-up plant fragments contained in arthropod frass,decomposition by bacteria and fungi would even-tually occur but at a much slower rate. The de-composition process is far more efficient if leavesare shredded first.

Protozoa, rhabditid nematodes, bacterial- andfungal-feeding mites, and springtails mineralizenutrients pooled in the microbial biomass of therhizosphere. By grazing on bacteria and fungi, N isreleased in the form of nitrogenous wastes, someof which are absorbed by the disturbed microbialsheaths of roots.

Earthworms2—Earthworms require organicmatter in various stages of decay and in variouslocations. Three broad groups of earthwormshave been described by Bouche (1977): epigeic,endogeic, and anecic. Epigeic worms are typicallysmall, darkly pigmented, and reside in leaf litterand under the bark of decaying logs. Endogeicslive in the mineral soil and consume organic matterwithin the soil or at the soil-litter interface. Theyare larger, less pigmented to unpigmented, havelonger lives, and have lower reproductive rates.Anecics are those worms that inhabit a permanentor semipermanent deep vertical burrow andemerge at night to consume relatively fresh plantdetritus on the surface. These are the largest andlongest lived earthworms.

2 This section is based on James (1995).

5

In a forested site, earthworms would be expectedto have the following functional roles:

Organic matter comminution—By reducing thesize of organic matter particles during passagethrough the worm, the organic matter is mademore accessible to action by other decomposers.

Nutrient cycling—Earthworms cycle nutrientsthrough their feces, through their urine, and indeath, through their decomposing bodies. Theseearthworms digest organics and thus mineralizesome of the nutrients bound in them. All earth-worm excreta have higher levels of available ma-cronutrients and cations than the material ingested(see Lee 1985). Urine is also a source of availableN, and the soft body tissues of earthworms readilydecompose at death.

Soil structural modification—Burrowing anddefecation create soil structures potentially signifi-cant (though the details are unknown anywhere) toother soil biota. These soil structures promote amore stable aggregation in the presence of soilwater.

Transfer of organic matter to the soil—Con-sumption of surface litter results in some defeca-tion in the mineral soil, particularly if wormsretreat into the mineral soil to avoid unfavorableclimatic conditions in the litter.

Food for other animals—Predators of earth-worms include small mammals, beetle adults andlarvae, centipedes, spiders, some flies, birds, rep-tiles, and amphibians.

Epigeic worms are known from two sites in thebasin assessment area, in an Engelmann spruce(Picea engelmannii Parry ex Engelm.)-subalpinefir (Abies lasiocarpa (Hook.) Nutt.) forest typewithin the Grand Teton National Park, and from ariparian area within an area designated as agricul-tural land.

Native and exotic endogeic species occur in a widerange of habitats including forest and savannah,grassland-shrubland (including exotic grass pastureand seral stages after cessation of agriculture), andcultivated land. Piper (1982) demonstrated theimportance of enchytraeid earthworms as detriti-

vores by finding populations of up to 68,000 persquare meter in a mature stand of Pacific silverfir (Abies amabilis Dougl. ex Forbes) near Sno-qualmie Pass. Endogeic species, though they arethe majority, are the least known of all earthwormsbecause their lifestyles are not easily observed.The fraction of the soil organic matter on which agiven species feeds is known only for a few spe-cies, and for none of those present in the basinassessment area. Factors influencing populationsof native species are completely unknown. If theyare comparable to other earthworms, soil moisture,soil temperature, organic matter quantity and quali-ty, and soil pH are probably the most importantfactors (Lee 1985).

Anecic earthworms are not known to be associatedwith the natural vegetation in the basin assessmentarea. If present, their unique contributions wouldbe the transfer of relatively fresh plant litter fromthe surface to deep levels of the soil and the crea-tion of deep vertical burrows, which assist waterinfiltration. Other earthworms can contribute tothese processes but not directly or effectively.Anecics also provide food resources accessible toendogeic worms by the deposition of fecal organicmatter in the soil.

Mollusks3—Over 150 described species of landsnails and slugs are found in the basin assessmentarea. Most are found in moist forest environmentsand in areas around springs, bogs, and marshes.Basalt and limestone talus slopes are also impor-tant habitats for some species. The land snails andslugs are mostly herbivores. All are also detriti-vores, and many also consume animal (includingmammal-insect) fecal matter. Some prey on otherland snails. Primary food for the herbivores, inaddition to soil and fecal matter, includes greenand fallen deciduous tree leaves, understory vege-tation, large fungi, and inner bark. Many mam-mals, reptiles, amphibians, and some birds preyon land snails and slugs. Various insects prey onsnails or parasitize them. Some land snails areintermediate hosts for parasites of vertebrates.Snail shells are used as domiciles, shelters, or egglaying sites by various arthropod taxa.

3 This section is based on Frest and Johannes (1995).

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Soil micro-organisms4—Other organisms in thesoil, such as bacteria, fungi, protozoa, nematodes,and microarthropods, play critical roles in main-taining soil health and fertility (Coleman and others1992). Their roles include (1) decomposing plantmaterial by bacteria and fungi; (2) immobilizingnutrients in soil by bacteria and fungi in the formof their biomass and secondary metabolites suchas waste or defensive products; (3) improving soilaggregate structure, which increases waterholdingcapacity, clay surface interactions with nutrients,and plant root architecture; (4) altering the soil pH;(5) mineralizing nutrients by protozoan, nematode,and microarthropod predation of bacteria andfungi; and (6) controlling disease-causing organ-isms by competition for resources and space, con-trol of soil micronutrient status, and alteration ofroot growth.

Productive ecosystems tend to retain nutrients.Over time, nutrients are metabolized to forms lessavailable for plants and animals, such as phytates,lignins, tannins, and humic and fulvic acids. Fornutrients to once again become available to plantsand animals, they must be mineralized by the in-teraction of decomposers and their predators.These populations and their interactions are impor-tant to ecosystem stability, including predator andprey interactions, mutualisms, and disease.

As total ecosystem productivity increases, biodi-versity within the soil food web also increases.The greater number of interactions of decompos-ers, their predators, and the predators of thosepredators, the slower the losses of nutrients fromthat system. In undisturbed ecosystems, the pro-cesses of immobilization and mineralization aretightly coupled to plant growth. After disturb-ance, this coupling is lost or reduced. Nutrientsare no longer retained within the rhizosphere,thereby reducing the productivity of the ecosys-tem and causing problems for systems into whichnutrients move, especially aquatic portions oflandscapes.

Thus, the soil food web is a prime indicator ofecosystem health. Measurement of disrupted soilprocesses, decreased bacterial or fungal activity,change in the ratio of fungal to bacterial biomass,decreases in number or diversity of protozoa, orchange in nematode numbers, nematode commu-nity structure, or maturity index, can serve to in-dicate problems long before the natural vegetationis obviously affected.

One estimate of bacteria species in the basin as-sessment area is about 160,000 species each inforests, grasslands, and agricultural fields, totalingabout 480,000 species in these three environ-ments.5 This estimate is approximate and willchange with new field information.

No study has been conducted on the total numberof bacteria species or even uniqueness of speciesin soils of the basin assessment area. Within thebasin assessment area, one study has discovered asmall set of unique mutualistic bacteria that sup-press weeds in the Palouse; and another study isexploring the role of beneficial bacteria that aidcrop plant growth.

In one estimate, there are from several hundred toperhaps a thousand species of protozoa in foreststands and pasture or grassland, and perhaps sev-eral hundred in agricultural fields, totaling about1,000 to 2,000 in all three environments. Onereport states having found species of testate amoe-bae in samples from the Blue and Wallowa Moun-tains that have never been seen in any other soils(Ingham 1999).

Soil nematodes number perhaps 100 to 150 spe-cies in a healthy forest. Many soil nematodesagriculturally important in the basin assessmentarea are known, and their distributions are fairlywell understood.

Extrapolating from small soil samples, there areabout 100,000 soil ectomycorrhizal microfungispecies each in forest and grassland ecosystems.6

4 This section is based primarily on Ingham (1994).5 Extrapolations based on work by James Tiedje, Professor,Center for Microbial Ecology at Michigan State University,East Lansing, MI 48824.

6 Estimates based on work by T. Bruns, Associate Professor,University of California, Berkeley, CA 94720.

7

There may be about equal numbers of other formsof microfungi, but they are essentially unstudied inthe basin assessment area. One study has foundunique mycorrhizal species in larch and mixed-conifer stands of the Blue Mountains (Ingham1994).

Implications of management practices on detri-tivores and nutrient cycling7—Detritivores arelikely to be affected by fire, soil compaction, andremoval of large woody debris. The effects of fireon soils, coarse woody debris, and the organismsinhabiting these habitats are many and highly vari-able. They depend on the timing and intensity ofthe fire and the amount of surface fuels consumed.Fire can affect soils physically, chemically, andbiologically; it can alter nutrient cycles, soil devel-opment, and site productivity. If litter or the criticalorganic horizons are not entirely destroyed by fire,then fire effects on the soil are usually minimal(Harvey and others 1994). Three areas of concernfor invertebrates are direct effects of fire on theseorganisms, the role of fire in forest or range suc-cession, and soil chemistry. These relate primarilyto intense fires that leave little undamaged refugia.In fire-adapted systems, direct effects on inverte-brates are thought to be slight. In systems wherelarge volumes of fuel litter and coarse woodymaterialare present, however, higher intensity fires maypose hazards to organisms such as land snails,which recolonize slowly. Direct effects on inverte-brates may be minimal if refugia of litter andcoarse woody material are retained. Some coarse-woody-debris feeders are attracted by smoke andcolonize still-smoking trees (Furniss and Carolin1977).

Removal of organic matter by fire has similar ef-fects on forest and range succession. In the forest,loss of organic matter may change the ratio offungi-bacteria to favor bacteria. This favors grass-es rather than woody vegetation, which is notnecessarily the desired successional course in for-estry. In rangelands, the consumption of organicmatter and the subsequent change to a bacteria-

dominated food web is beneficial to maintenanceof grasses. The effects on litter or soil inverte-brates by wildfire in rangelands dominated bycheatgrass (Bromus tectorum L.) is unknown.

Coarse woody material serves as primary habitatfor invertebrate predators, xylophages, and detriti-vores, habitat of prey for other organisms, and asa carbon source for the soil food web. Little isknown about how much litter and coarse woodymaterial and what sizes and species are necessaryto continue ecosystem functions of associatedinvertebrates (Torgersen and Bull 1995). It isassumed that standards intended to provide preyfor vertebrate species will suffice to continue thefunctions of the invertebrates (Bull and others1997).

Compaction of soils has implications for the soilfood web as well as other functional groups. Com-paction occurs from use of machinery on the landand the effects of large herbivore grazing. Grazingcompacts soils if these activities are concentratedin small areas with many animals, and on areaswith fine-textured soil. Compaction reduces soilpore size, thereby resulting in loss of nutrient re-tention and an increase in the bacterial componentof the soil-based food web. This may cause a rev-ersal of succession in the forested environment,with a subsequent negative effect on cyanobacte-ria, lichens, and mat-forming ectomycorrhizalfungi. With loss of the ectomycorrhizal fungi, treeproductivity declines. Compaction changes thecommunity of nematodes, favoring bacteria androot-feeding species. Root-feeding nematodes canbe detrimental to tree and grass seedling survival.Compaction effects are particularly undesirable forgroups such as mollusks and earthworms, whichmay occupy specific habitats or which cannotdisperse quickly.

Overgrazing can adversely affect mollusks becauseof trampling as well as disruption of their favoredriparian habitats by the congregating of livestocknear water sources.

Tilling to reduce compaction as well as othermeans of physically mixing the duff and soil canadversely affect many functional groups. Disrup-tion of the duff-litter layer has immediate effects

7 This section is based primarily on discussions during theexpert panels on soil-nutrient cycling and litter and coarsewood detritivores (see appendix 1).

8

on water and thermal relations and disrupts habitatfor many functional groups inhabiting the woodymaterial and litter, as well as forb and floweringplant communities. Mixing affects the soil foodweb by breaking roots, fungal mats, and changingthe water and thermal conditions that encouragebacteria populations.

Predators8

This section covers the macroinvertebrate terres-trial predators, which are arthropods of the class-es Arachnida and Insecta. Principal among theseare the spiders (Arachnida: Araneae), and themajor predatory insect groups, the true bugs (Het-eroptera), lacewings (Neuroptera), beetles (Co-leoptera), ants (Hymenoptera: Formicidae), andsocial wasps (Hymenoptera: Vespidae). A basicview of the diversity of predatory arthropods isprovided, including their ecological function, andfactors thought to affect their abundance and dis-tribution. For more information on predatory Het-eroptera, see Lattin (1995b). For a discussion ofthe functionally related “insect parasitoids,” seeJohnson (1995). Not included in this report are thefollowing groups of invertebrates that serve asimportant natural enemies of other invertebrates:(1) predatory mites, most of which are just largeenough to be seen without the use of a micro-scope, and that function as important microarthro-pod predators in many habitats; (2) predatorynematodes, which occur primarily in the soiland soil interface (Ingham 1994); (3) insect parasi-toids, primarily wasps and true flies, in which thelarva(e) consume a single host during development(Johnson 1995); and (4) those predatory insectsthat spend most of their lives in the aquatic habitat(e.g., dragonflies).

Predator diversity within the basin assessmentarea—We estimate that between 3,544 and 6,636species (median = 5,090 species) of terrestrialarthropod predators occur in the basin assessmentarea (appendix 3). This estimate was obtained byidentifying those families of terrestrial arthropods

that are primarily predaceous, and then summingthe ranges of species number estimates within thebasin assessment area for each family. The widerange of this estimate is due to inadequate infor-mation on many of the families. Despite the lackof accurate knowledge of species diversity, eventhe lower estimate is several times greater than thediversity of all vertebrate species within the basinassessment area.

One hundred and twelve families of predatorswere identified in the survey, assigned to 15 ordersand 3 classes (insects, centipedes, and arachnids)within the phylum Arthropoda. Five large orderscontain 88 percent of the predator species in thebasin assessment area: spiders (Araneae: 1,631species), beetles (Coleoptera: 1,308 species),wasps and ants (Hymenoptera: 700 species), trueflies (Diptera: 460 species), and true bugs (Het-eroptera: 367 species). Arthropod predators arefound in great diversity in every habitat typethroughout the assessment area and prey on virtu-ally every type of available arthropod species, aswell as some mollusks and annelids. Spiders andants dominate the predator arthropod fauna associ-ated with vegetation, and beetles, ants, and spidersdominate the surface and immediate subsurface ofthe ground. Some major taxa such as the spiders,ants, true bugs and beetles contain representativespecies common to habitats throughout the basinassessment area, whereas others, such as the scor-pions (shrub-steppe) and centipedes (forest floor)occur predominantly in certain habitats.

As a group, arthropod predators are a fundamentalpart of any functioning ecosystem, with this func-tion performed by a different species compositionin each major habitat type. McIver and others(1992) found that the species composition ofground-dwelling spiders common in conifer forestsof western Oregon is completely replaced by anequally diverse assemblage of different ground-dwelling species after clearcut harvesting. In gener-al, arthropod predators respond keenly to changesin microhabitat conditions that typically occur withboth natural and human-induced disturbance.

8 This section is based primarily on McIver and others (1995).

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Invertebrate predators and ecological func-tion—The primary function of arthropod preda-tors is the role they play within food webs. Buttheir relatively small size makes them potentialprey for vertebrate insectivores as well. In thissection, we will discuss these two functional roles,focusing on predation of forest pest populations,and by describing a case study of arthropod preda-tors serving as primary prey of critical wildlifespecies.

Evidence supports that arthropod predation hasbeen a major force in ecological systems for a longtime. In a long-term study of the arthropod com-munity of a desert lupine, McIver (1987, 1989)documented various evolved defensive adaptationsagainst predation, including mimicry, warningcoloration, and crypsis. In general, defensive adap-tations reflect the chronic influence of predationthrough evolutionary time (Edmunds 1974). Al-though vertebrate predators most often are impli-cated as responsible for the evolution of defensiveadaptations, behavioral and serological studies onthe lupine fauna identified arthropod predators asthe primary force behind some of the defensiveadaptations (McIver and Lattin 1990, McIver andTempelis 1993), thereby suggesting that arthropodpredator species play an active role in determiningthe species composition and relative abundance ofother arthropod species.

Predators also can play a major role energetically.Using isotopic tracers in a forest floor community,Moulder and Reichle (1972) showed that spiderswere the dominant predators, consuming each year2.3 times the mean standing crop of potential prey,and 44 percent of all forest floor cryptozoans(arthropods and mollusks). The importance ofspiders and predatory insects in maintaining thebalance of herbivorous and detritivore arthropodspecies is significant.

One of the best examples of how predators oper-ate is their role in suppressing forest insect pestpopulations (Morris 1963). A preliminary evalua-tion of the “HUSSI” database (Torgersen 1997)provides insight on the prevalence of predation onpest organisms. Over 300 entries in the databasereported observed predator-pest insect links, in-volving at least 71 predator species, preying on

pine tip moths, tussock moths, budworms, saw-flies, tent caterpillars, and bark beetles. A total of33 predator species has been observed to attackspecies of Dendroctonus alone.

Although the HUSSI database identifies a diversecomplex of predator species that prey on forestinsect pests, many studies in North America havedocumented that predators can play a significantregulatory role by suppressing pest populationbuildup, especially defoliator species (Mason andothers 1983). Predators have been implicated asprimary suppressive agents of Dendroctonus spp.(Furniss and Carolin 1977), Ips spp. (Jennings andPase 1975), pine tip moths (Bosworth and others1971), and the two principal defoliator species ofwestern coniferous forests, western spruce bud-worm (Choristoneura occidentalis) (Campbelland others 1983, Mason and others 1983, Masonand Paul 1988, Mason and Torgersen 1983, Torg-ersen and others 1983) and Douglas-fir tussockmoth (Orgyia pseudotsugata (McDunnough))(Mason and others 1983, Mason and Torgersen1987).

Studies on mortality of western spruce budwormpopulations have implicated bird and ant predationas primary factors (Torgersen and others 1990).In whole-tree exclosure experiments, several spe-cies of passerine birds were identified as mostinfluential in the upper third of the canopy andants (primarily Camponotus modoc W.M.Wheeler) more effective in the lower third. Pupalstocking studies also have implicated thatch ants(Formica haemorrhoidalis Emery) as significantmortality factors of western spruce budworm.Spiders also may aid in suppressing budwormpopulations, particularly when caterpillars are inthe earlier stages of development. These studiesclearly establish that spruce budworm are preyedon by various predators, including birds, ants,spiders, and other arthropods. Management tech-niques that enhance the role of these predatorsthroughout the budworm population cycle likelywill be of economic benefit because of decreasedloss of green trees.

Many studies have implicated predation as a pri-mary cause of mortality in Douglas-fir tussockmoth populations, including stocking experiments

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(Mason and Paul 1988, Mason and Torgersen1983) and key-factor analysis (Mason and others1983, Mason and Torgersen 1987). Primary pred-ators identified as mortality factors include thejumping spider (Metaphidippus aeneolus Curtis),philodromid hunting spiders, web-spinning spiders,heteropteran predators, and predaceous ants andbirds (Mason and Paul 1988, Mason and Torgers-en 1987, Wickman 1977). Although predation maycontribute to well over half the total mortality oftussock moth larvae and pupae during outbreakconditions, [however], even this level of suppres-sion may be inadequate to deflect the outbreakpopulation trajectory (Mason and Wickman 1988).Hence predation is typically thought to exert mostof its influence during nonoutbreak (or endemic)phases of the population cycle of the moth (Mason1987). Management activities that improve theimpact of predation during these endemic condi-tions are therefore most likely to either defer ordecrease subsequent population levels during theoutbreak phase. For example, in the NortheasternUnited States, spider populations on spruce aresignificantly higher than on balsam fir, and thusaltering the relative abundance of these tree spe-cies may influence the total suppressive effect ofarthropod predation on populations of the sprucebudworm Choristoneura fumiferana (Clemens)(Jennings and others 1990).

Although predation is their primary ecological role,arthropod predators also serve as prey for all class-es of insectivorous vertebrates, both aquatic andterrestrial. Terrestrial arthropod predators are acommon component of drift in streams, wherethey serve as prey for freshwater fish, includingsalmonoids. Because they lack defensive chemi-cals and are soft-bodied, larger spiders are idealprey for nesting and overwintering birds (Wise1993). Social insect predators are common prey ofvertebrates: yellowjackets have been found infeces of pine marten (Martes americana) (Torg-ersen 1999), and carpenter ants are the primaryprey of pileated woodpecker (Beckwith and Bull1985). The carpenter ant (Camponotus modoc)nests in down or standing dead wood, usually

greater than 38 centimeters (15 inches) in diameterand in the earlier stages of decay. This places themsquarely within the foraging habitat of woodpeck-ers, and they have been estimated to make upmore than 90 percent of the diet of pileated wood-peckers in Blue Mountains mixed-conifer forests(Beckwith and Bull 1985, Torgersen and Bull1995). Pileated woodpeckers are one of the moreimportant cavity builders in older forests (Bull1987), providing [nesting] habitat for many otherorganisms, including some, like carpenter ants[themselves], that feed on spruce budworm. Thus,C. modoc, as a predator of spruce budworm, andas the primary prey of pileated woodpecker, canbe regarded as a keystone species, having an eco-logical effect possibly greater than its relativeabundance would imply. Furthermore, because C.modoc generally nests in large-diameter deadwood, its abundance (and its function) can bemanaged roughly by leaving particular levels ofthis structure in the forest.

Implications of management practices on pred-ators9—Predation is an ecological process funda-mental to healthy managed ecosystems. Thechallenge for managers is to preserve this processso arthropod population fluctuations are containedwithin some desirable range. In some cases, main-taining predatory function may be as simple asretaining landscape structures predators are knownto require, such as down wood, snags, specialhabitat features (hydrological function of a bog orspring), forbs, shrubs, and trees of various speciesand sizes. These are features to which predaceousarthropods will respond in much the same manneras vertebrates (Thomas and others 1979). Unlikethe vertebrates, however, little is known abouthow particular wildland management practicesinfluence predatory arthropod species composition,abundance, and distribution. Several studies sug-gest that predators as a group are particularly vul-nerable to disturbances (Kruess and Tscharntke1994, Schowalter 1995).

9 This section is based on McIver and others (1995) anddiscussions during the expert panels on range herbivores andparasites and predators (see appendix 1).

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The structure of the physical environment onwhich arthropod predators depend for hunting andnesting is important for almost every predator spe-cies. The natural variability in spider abundanceamong sites suggests spider populations can bemanaged (Mason 1992). Plant architecture (size,number, and arrangement of leaves, needles, andbranches) influences canopy spiders (Gunnarsson1988, Stratton and others 1979), and plant speciescomposition influences spider abundance. Jenningsand others (1990) recorded a significantly greaternumber of spiders in spruce as opposed to hem-lock in forests of the Northeastern United States.Physical structures like down logs provide nesting,foraging, or hiding habitat for important predatorspecies, such as ants (Formica spp., Camponotusmodoc) (Harmon and others 1986, Torgersen andBull 1995), beetles, and spiders.

Silvicultural practices can profoundly affect preda-tor species composition. In coniferous forests ofwestern Oregon, clearcutting causes a completereplacement of forest-dwelling litter spider specieswith species adapted to sunny open places (McIv-er and others 1992). An extensive study in Finland(Huhta and others 1967) showed severe effects onspiders and other soil invertebrates by clearcutting,devastating effects by clearcutting and burning,and substantial changes even from partial cutting,apparently caused by change in microclimate fromthe loss of a closed canopy. Selective cutting moretypical of east-side forests is not likely to have assevere an effect, but more work needs to be doneto determine the connection among silviculture,predator species composition, and the quality andquantity of ecological service that predator speciesprovide. Structural diversity, including differentages of conifers and angiosperms and standing anddown dead wood are extremely important in main-taining the microhabitats, moisture regimes, lightregimes, food plants, and prey base for predators.

Any disturbance affecting habitat will affect thespecies dependant on that habitat. For example,the short fire-return intervals on cheatgrass-domi-nated rangelands may eliminate dominant predatorspecies such as the western thatching ant, Formicaobscuripes Forel. Although thatching ant coloniescan survive fire by maintaining the queen and

brood belowground, postfire survival is challengedby lack of resources because the sagebrush-feed-ing Homoptera the ants depend on for honeydew(carbohydrates) are typically eliminated. Hencecolonies generally are reduced by fire to less than20 percent original size, and fires returning everyfew years likely will extirpate these disturbed colo-nies. Systems with short fire-return intervals (forexample, cheatgrass and planted crested wheat-grass dominated) will therefore tend to favor“weedy” ant species with different ecologicalfunctions.

Pollinators10

About two-thirds of all flowering plant speciesbenefit from insects visiting their flowers(Axelrod 1960). In the absence of insect pollina-tors, these plants would reproduce only marginally.Bees (Hymenoptera), butterflies and moths (Lepi-doptera), flies (Diptera), and some beetles (Co-leoptera) are the main insect taxa that pollinateflowers. Moths are extremely important pollina-tors, and may be the main insect pollinators ofplants that bloom mainly at night. Many deep-throated flowers require hawk-moth pollinators(Grant 1983). On the other hand, butterflies areprobably less important as pollinators than general-ly supposed (Jennersten 1984). Although beetles,moths, and butterflies play important roles in polli-nation, this section will focus on bees.

Most native bees are solitary rather than social.Individual females search for sites where theyconstruct nests, and then provision the nests withpollen and nectar as food for their progeny. Mostnests are constructed in either soil or wood, withthe number of ground-dwelling species predomi-nating by about 3:1.

Most soil-nesting species are also burrowers. Onlya few use burrows abandoned by other animals,notably bumblebees. Soil nest sites can range fromvertical clay embankments to alkali flats and agri-cultural fields; they may be compacted and barrenor aerated and vegetated. The preferred or evenacceptable type of soil for nesting is unknown for

10 This section is based primarily on Tepedino and Griswold(1995).

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most species. This is because of the difficulty offinding the solitary, dispersed nests of many spe-cies, because existing descriptions of nesting sitesmay not be accurate, and because soil informationis rarely recorded.

Except for carpenter bees, and perhaps a fewother taxa, bees that nest in wood are nonburrow-ing. They depend primarily on holes, mostly indead snags, stumps, logs, twigs, and stems thathave been excavated and vacated by members ofthe 177 genera of boring beetles in the basin as-sessment area (Arnett 1960). Their natural nestinghabits are poorly understood. Although woody andsoft-stemmed material are a necessity for thesebee species, the preferred amount, plant species,diameters, and ages are generally unknown.

Bee diversity within the basin assessmentarea—Based on 8,350 specimen records,11 647species of bees presently are known to occur inthe Columbia River basin. The actual numberof bee species in the basin assessment area isbelieved to be substantially higher as there has notbeen extensive collecting in many parts of thisregion. Little biological or ecological informationexists for most of these recorded species. Becauserecords frequently do not include a flower associa-tion, little is known about the foraging preferencesof many species. Also, in most cases where re-cords on flowers do exist, the purpose of the visit,for example collecting nectar or resting, is notstated. Based on other areas in the West that havebeen sampled more extensively, Tepedino andGriswold (1995) estimated the actual number ofbee species in the basin assessment area is closerto 1,000.

Functional roles of bee pollinators—Bees arethe only organisms, with a few exceptions, thatdepend exclusively on pollen and nectar for foodthroughout their lives. For many plants, without

bee-facilitated pollination, few, if any, seeds orfruits would be produced. An exception is at higherelevations where flies and moths assume increasedimportance (del Moral and Standley 1979), appar-ently because of their greater ability to cope withhigh altitudes and cold temperatures. Flies mostlyvisit open, shallow flowers. Bumblebees accountfor a large proportion of bee visits to flowers withrestricted accessibility at higher elevations.

Bees can influence the genetic variability of theseeds produced by the plants they visit. They canaffect the rate of inbreeding in plants with self-compatible flowers by their movement patternswithin and between plants. More flower-to-flowervisits on the same plant will increase the likelihoodof self-pollination occurring. Bees also might influ-ence genetic variability of plant populations by thefrequency of flights among populations duringforaging trips. Such trips would result in gene flowamong populations and would tend to make popu-lations more uniform genetically by counteractinggenetic drift and natural selection for site-specifictraits.

The products of pollination, fruits and seeds, areimportant not only to the plants producing thembut to the many birds, mammals, and insects utiliz-ing them as food for all or part of the year. An ideaof the diversity of organisms that eat fruits andseeds and the amount eaten can be gained fromJanzen’s (1971) review of seed predation.

Finally, ground-nesting bees, particularly thosenesting in aggregations of thousands of nests,move large amounts of soil in digging their mainburrows and side branches, thereby contributing tothe cycling of the soil layers and of nutrients in thesoil.

Implications of management for bees12—Fourmajor concerns about the effects of managementpractices on bees are (1) nest site habitat, (2) flow-ering plant resources, (3) exotic flora and fauna,and (4) pesticides.

12 This section is based on discussions during the expert panelson pollinators (see appendix 1).

11 U.S. National Pollinating Insects Collection. Publishedand unpublished reports. On file with: USDA AgricultureResearch Service, Bee Biology and Systematics Laboratory,Utah State University, Logan, UT 84322-5310.

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Nest site habitat—The nest sites of ground-nesting bees may be subject to various disturb-ances. Management activities such as grazing,mechanized activities, off-road vehicle use, andsubsoiling can damage maturing progeny in the soiland can disrupt current nesting activity. Sites invertical or near-vertical embankments are subjectto erosion, whereas sites in more level ground arevulnerable to compaction. The impacts of constantor heavy use differ greatly from site to site. Limit-ed compaction of heavier soils may be tolerable oreven beneficial to certain ground-nesting bees.Bees found in light and sandy soils, however, areextremely sensitive to disturbance because highpopulation densities and endemic species are fre-quently found in these soils. Human activities alsocan obliterate or change the subtle landmarks adj-acent to nest-holes that bees use to relocate theirnests when returning from foraging trips. Thus,disturbance early or late in the year, while beesand plants are not active, will tend to cause feweradverse effects. In addition to seasonal mitigation,any reduction in the intensity and frequency ofground disturbance will help to maintain adequateground-nesting habitat and provide time for recov-ery and recolonization of sites.

Habitat availability for wood-nesting bee species isaffected by any management practices such asprescribed burning and intensive tree harvestingthat remove nesting resources. Removing treesfrom the overstory opens up forest habitat forground-nesters by increasing light penetration andabundance of flowering plants. In rangeland, firewill kill bees directly and burn up substrates forwood-nesters. The season of removal is not criticalin closed-canopy forest because there is little utili-zation by bees except in canopy gaps. In range andopen forest, however, season of disturbance willmatter because resident bees will be killed.

Flowering plant resources—All bees depend onthe pollen and nectar of flowers for their suste-nance throughout their life cycle. Many species arespecialized and collect the pollen of a restrictedgroup of plants. Specialization can range fromfairly broad (for example, pollinating composites)

to generic level restrictions. Other bees are gener-alists such as the Halictinae and Bombinae, whichvisit various flowers on individual foraging trips.

For plants having known specialist bee pollinators,grazing, burning, and other activities with similarimpacts on the flora should be timed to periodswhen these plants are not flowering. Changes indomestic grazing activities can promote both nativeplant and bee diversity. Careful rotations and ex-clusions of selected rangelands can enhance diver-sity, particularly in higher elevation and forestedsites. Any management to reduce cheatgrass orother annuals will favor angiosperm diversity andpollinator abundance. Grazing by sheep is particu-larly disruptive to flowering plant diversity becausesheep are forb eaters. Herbicides are the mostobvious immediate detriment to floristic diversity.Current management policies that limit broadcastapplications of herbicides can help maintain plantand bee diversity. Harvesting methods that leaveclusters of trees encourage floral diversity whilemaintaining other habitat requirements.

Effects of exotic flora and fauna—This issueaddresses effects of intentional and unintentionalintroduction of both plants and animals includinghoneybees (Apis mellifera L.). As stated in thepreceding section, management activities that pre-vent the introduction of or reduce the dispersal orextent of communities of exotic plants such ascrested wheatgrass (Agropyron cristatum (L.)),Russian thistle (Salsola kali L.), kochia (Kochiaprostrata and K. scoparia L.), and cheatgrass andthat increase native floral species will promotenative bee communities.

The intentional introduction of nonnative bees ornative bees to nonnative areas for the pollinationof agricultural crops, as well as accidental intro-ductions, poses the threat of competitive displace-ment of native bee species. An example of theconsequences of such an introduction is the exoticleaf-cutting bee that pollinates exotic Centaureaspp. in California. This bee has displaced bothnative bees and other exotic species, includingApis, throughout its distribution. Stringent screen-ing criteria are necessary to prevent both intention-al and accidental introductions from displacingnative bees.

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Effects of pesticides—The use of carbaryl andmalathion insecticides to control grasshopper pop-ulations on rangelands adjacent to agriculturallands has significant detrimental affects on honey-bee colonies. Currently, the only alternative beingtested is the biological control, Nosema locustae.Use of chemical insecticides in forestry to suppressdefoliators such as western spruce budworm andDouglas-fir tussock moth may be detrimental tohoneybee colonies as well as native bees.

Although there are situations where insecticides arethe best choice, judicious use of them will mini-mize adverse impacts on bee diversity and abun-dance. Alternative control methods can be devel-oped to minimize adverse effects. When chemicalspraying is the treatment selected, nonsprayedstrips can be left as refugia for beneficial fauna;repeated applications on the same tract of landyear after year may be detrimental. The BLMguideline is that an unsprayed buffer be left aroundrare plants. The width of the unsprayed buffershould be determined on a case-by-case basistaking into account the expected distance of signifi-cant insecticide drift and the specifics of the repro-ductive biology of the plant and the ecology of thelikely pollinators.

Grassland Herbivores13

On grasslands, several arthropod groups functionprimarily as grazers and are important links in foodwebs. Most invertebrate grassland herbivores feedon various herbs, shrubs, and trees and are seldomconsidered pests. Some taxa like grasshoppers,however, are of economic importance when popu-lations reach outbreak levels and consume signifi-cant amounts of forage. In addition to being im-portant consumers of annual primary production,grassland herbivores are important food for vari-ous wildlife and are an especially critical resourcefor nesting birds and their broods in spring.

Many arthropods are grassland herbivores.Limited time and available expertise has focusedthis discussion on three groups: grasshoppers

(Acrididae) (Kemp 1995), moths and butterflies(Lepidoptera) (Hammond 1994), and true bugs(Heteroptera) (Lattin 1995b).

Grassland herbivore diversity—Within the basinassessment area grassland types, about 100 grass-hopper species exist. We know much more abouthow to suppress rangeland grasshopper popula-tions than we do about their specific ecologicalroles. Our knowledge about rangeland grasshopperecology originates from grasslands other than, andin many cases different from, those in the basinassessment area.

Grasshoppers are a complex group of herbivoresthat interact in space and time. At a specific loca-tion, it is common to find 15 or more grasshopperspecies throughout spring and summer. Althoughsome species are separated to an extent by differ-ences in phenology, considerable overlap of spe-cies occurs at a given site through summer. In spiteof the number of studies conducted on individualspecies of Acrididae (for example, Chapman andJoern 1990, Uvarov 1966, 1977) limited workhas been done on macroscale grasshopper speciesassociations (see Joern 1982 for microhabitatselection).

Less is known about Lepidoptera diversity inWestern grasslands, yet 302 species of butterfliesand moths were recorded from semidesert grass-lands of southeastern Oregon in Harney County(Hammond 1995b).

At least 307 species of true bugs exist in the basinassessment area (Lattin 1995b), many of whichare herbivores. We have knowledge of the generalbiogeographical distribution of the true bug faunaof the region based on collections at Oregon StateUniversity, Washington State University, Universi-ty of Idaho, University of British Columbia, andthe California Academy of Sciences (Lattin1995b).

Functional roles of invertebrate grassland her-bivores—Although all the insects being consideredact as primary plant consumers, their host specific-ity differs among groups. Most Lepidoptera larvaeconfine their feeding to a single family of plants.Grasshoppers display varying degrees of host plant

13 This section is based on information from three contractreports: Hammond (1994), Kemp (1995), and Lattin (1995b).

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specificity; however, the pest species are general-ists that graze on various grasses and forbs. Fortrue bugs, species feeding on grasses tend to havelower specificity than those feeding on trees.

Herbivory influences rates of nutrient cycling ofelements such as nitrogen and carbon. This func-tion is relevant in regard to species that consumelarge amounts of vegetation, such as generalistgrasshoppers in various range habitats, and plantbugs (Miridae) such as Labops hesperius Uhler incrested wheatgrass and some Lygus on Kochia(Moore and others 1982).

Small vertebrates such as passerine birds, rodents,shrews, and bats are particularly dependent oninsects for a dietary protein source when rearingtheir young in spring and early summer. Nestingsuccess for the western sage grouse (Centrocercusurophasianus) is tied to their dietary needs, whichare primarily succulent forbs and insects (Klebe-now and Gray 1968). These first-order predatorsthen become food themselves for [arthropods and]other second-order predators such as hawks, owls,coyotes (Canis latrans), and bobcats (Lynx rufus).

Many rangeland herbivores, particularlyLepidoptera, also function as pollinators ofherbs and shrubs (see “Pollination” section).

Implications of management for invertebrategrassland herbivores14—There are three majorissues related to management for grassland herbi-vores: effects of plant community composition,effects of exotic flora and fauna, and effects ofinsecticides.

Changes in plant community composition affectthe herbivore community because of changes inthe availability of their host plants and the abun-dance and faunal composition of predators. Man-agement activities that change vegetation structure,vegetation biomass, and plant species composi-tion can affect presence and densities of grasslandherbivores. A diverse insect herbivore fauna is bestensured by maintaining a structurally and taxo-nomically diverse floral community.

Season-long grazing can alter plant communities toearlier seral stages with increased likelihood ofweedy species. Such conditions increase the prob-ability of a less diverse grasshopper communityeasily dominated by pest species such as Melano-plus sanguinipes (F.), Oedaleonotus enigma(Scudder), and Aulocara elliotti. Season-longgrazing also could reduce Lepidoptera diversitybecause of the loss of larval food plants (Ham-mond 1995a). Hammond and McCorkle (1983)found a rich diversity of plants and butterflies onpristine bunchgrass prairie, whereas adjacent over-grazed rangeland separated by a fence had fewplants or butterflies. Grassland physiognomy andspecies composition can be manipulated to in-crease species diversity of grassland herbivoresand to reduce the likeli-hood of irruptive outbreaksof pest species. The intensity, duration, season,and spatial extent of grazing regimes all are factorsthat can be restructured to favorably alter plantcommunities.

Fire will have little direct effect on insect herbivorepopulations unless burns are timed to kill a sub-stantial portion of individuals emerging that seasonor occur on habitats of limited extent. The effectof most concern is how fire alters the plant com-munity composition. If burning results in domi-nance by early successional forbs, especially inassociation with other disturbances, these con-ditions could result in outbreaks of some herbivo-rous invertebrate species, at least in the short term.A cool fire may favor Lepidoptera by opening upthe community to their preferred food plants. Ahot fire could result in mortality of shallow-rootedplants, which consequently could decrease herbi-vore diversity.

The second issue related to management for grass-land herbivores is the invasion of exotic flora andfauna. Exotic flora such as cheatgrass (Bromustectorum L.), knapweeds (Centaurea spp.), andleafy spurge (Euphorbia esula L.) have invadedand replaced native bunchgrasses and herbaceousplants on many basin assessment area grasslands.In addition, large areas of degraded grasslandsthroughout the West have been artificially plantedwith monocultures of exotic crested wheatgrass(Kochia prostrata) to provide livestock forage and

14 This section is based primarily on discussions during theexpert panel on rangeland herbivores (see appendix 1).

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prevent soil erosion. Most native insects are unableto exploit this new resource. Thus, generally areduction in grassland insect diversity occurs (in-cluding predatory species), leading to the specificfavoring of one or a few species of the community(for example, various species of grasshoppers, thetrue bugs Irbisia pacifica Uhler and Labops hes-perius Uhler in crested wheatgrass, and Lygus spp.bugs in Kochia (Lattin and Christie, in press; Lat-tin and others 1995; Moore and others 1982).

The consequences of proposed introductions ofexotic natural enemies (for example, scelionid eggparasites and fungal pathogens) to control nativegrasshoppers are unclear. Such actions may disruptnatural interactions in unanticipated ways—theeffect on native biological control agents is un-known. Also, only a small proportion of grasshop-per species are pests, and poorly researched bio-logical control programs could put other species atrisk. Risks can be reduced by carefully assessingthe possible side or cumulative effects for signifi-cant nontarget species.

The third issue related to management for grass-land herbivores is the role of insecticides. Epidem-ic grasshopper populations on grasslands adjacentto agricultural areas are routinely controlled by theapplication of insecticides. Broad spectrum insecti-cides like malathion and carbaryl drastically reduceboth species diversity and densities of grasslandgrasshoppers. Furthermore, many nontarget spe-cies including desirable Lepidoptera, bees, beetles,and aphids are destroyed. Some of the arthropodsaffected are predators of grasshoppers that wouldnormally exert pressure to reduce high grasshopperpopulations. Insecticides also may negatively affectbirds feeding their nestlings and other vertebrates(for example, amphibians, reptiles, small insectivo-rous mammals, etc.) if most of their prey base iskilled or contaminated. Bait applications of carbar-yl are less harmful to flying nontarget insects butmay negatively affect ants as well as other surface-active herbivores and omnivores.

The impacts of grasshopper controls on nontargetassociated fauna can be mitigated in several ways.First, use selective agents that kill only the targetor closely related species (for example, Nosemalocustae, fungal, and viral pathogens) of pest

grasshoppers. Nosema locustae can be used inmany cases to reduce densities of grasshopperswithout drastically altering community compositionor impacting nontarget organisms. Although N.locustae reduces feeding on plants by about 50percent, there is not the immediate mortality ofgrasshoppers as there is with chemical insecticides.This is because grasshoppers are killed graduallyand cadavers quickly eaten by other grasshoppers,which aids the horizontal transmission of N. locus-tae. Public education and explicit goals such asvegetation protection rather than insect control willbe necessary to gain acceptance for alternativecontrol methods. Changing grazing practices thatpredispose sites to pest species outbreaks may bethe best long-term solution.

Forest HerbivoresSeveral groups of immature or adult invertebratesare primary consumers feeding on forest forbs,shrubs, and trees. Through this function, they in-fluence forest ecosystem processes directly orindirectly. Many are prey of various invertebrateand vertebrate predators, and they provide copiousfeces and corpses for detritivores.

Forest herbivorous insects have traditionally beenviewed as pests that interfere with managementobjectives and damage forest resources. Manage-ment concerns and research emphases have con-centrated on single species (principally tree defolia-tors and bark beetles), and then only during out-breaks (Huffaker and others 1984). Pest-relatedwork has been useful in providing information onhow these organisms affect other parts of theforest ecosystem (including influences on forestsuccession) and has provided the necessary toolsto help managers reach desired objectives. Thegreatest need is for research that examines thelong-term effects or beneficial impacts of individu-al insect species and insect assemblages on thewhole ecosystem (Huffaker and others 1984,Stark 1987).

Within this assessment, two other efforts haveexamined aspects of arthropod forest herbivory.Hessburg and others (1995) assessed the land-scape susceptibility to major defoliator and barkbeetle disturbance, and Kurtz and others (1994)

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modeled the role that certain bark beetle and defo-liator species play in forest succession. Althoughthese topics are addressed in this paper, we referthe reader to the above reports for more detailedassessments.

The taxonomic groups addressed in this section aremoths and butterflies (Lepidoptera) (Hammond1994, Miller 1995, Wagner and McMillin 1994),bark beetles (Coleoptera: Scolytidae) (Ross 1995)and their associated mites (Acariformes) (Moser1994), true bugs (Hemiptera: Heteroptera) (Lattin1995b), saw-flies (Diprionidae and Tenthredinidae)(Wagner and McMillin 1994), and aphids (Aphid-idae) (Ross 1995).

Functional roles of invertebrate forest herbi-vores15—Forest invertebrate herbivores affectforest ecosystem processes directly and indirectlythrough (1) microclimate and water relations, (2)carbon and nutrient cycling, (3) energy flow, (4)plant succession or community structure, (5) foodsources for other organisms, (6) wildlife habitat,(7) pollination of plants, (8) watershed properties,and (9) fuel conditions and fire hazard, (Haackand Byler 1993, Schowalter 1981, 1994). Thefollowing discussion provides examples.

Microclimate and water relations—Reductions inpercentage of canopy cover or basal area by in-sect-caused defoliation or mortality can influenceinterception of precipitation, evapotranspiration(Schowalter 1994), light penetration, and windspeed (Speight and Wainhouse 1989). In addition,defoliation or tree mortality temporarily removesactively transpiring foliage from the forest canopy(Klock and Wickman 1978, Schowalter 1994).This reduces the flow of water from the root zoneto the tree canopy and can lead to reductions insoil-water depletion in the stand (Klock and Mc-Neal 1978 unpublished from Klock and Wickman1978). These authors suggest warmer spring andsummer soil temperatures, with increased soilmoisture caused by changes in canopy exposurefrom insect defoliation, should provide a more

favorable microclimate for biological activity. Envi-ronmental conditions, therefore, seem more favor-able for decomposition of organic matter indefoliated stands compared to nondefoliated stands(Klock and Wickman 1978), especially during dryperiods (Schowalter and Sabin 1991). Further-more, the improved water balance, as a result ofdecreased transpiration, may enhance plant surviv-al during drought (Schowalter 1994).

These microclimatic changes from defoliator-caused reductions in the canopy are likely to betemporary effects (Speight and Wainhouse 1989,Stark 1987). In contrast, when tree mortality oc-curs, changes in wind speed within the stand andincreases in sunlight and rainfall within the affectedarea may persist until the forest is reestablished(Speight and Wainhouse 1989).

Nutrient and carbon cycling—The importanceof arthropods in contributing to biomass decompo-sition, carbon cycling, nutrient cycling, maintain-ing soil fertility, and energy flow in forest ecosys-tems, has been proposed by Carpenter and others(1988), Haack and Byler (1993), Harmon andothers (1986), Mattson and Addy (1975), Schow-alter (1981, 1994), Schowalter and others (1991),and Stark (1987). Schowalter and others (1986)suggest that herbivore-controlled canopy-litternutrient fluxes in forested ecosystems depend onplant species composition, the particular herbivoresinvolved, changes in microclimate resulting fromcanopy opening, and the amount, composition,and seasonal pattern of material transferred rela-tive to normal litterfall.

Herbivory influences both short- and long-termnutrient cycling processes in forest ecosystems(Schowalter and others 1986). Modest defoliation(for example, less than 7 percent) can return asmuch as 30 percent of foliage standing crop ofpotassium and 300 percent of foliage standingcrop of sodium to the litter (Schowalter and others1981, 1986, 1991). In addition, considerableamounts of mobile elements are returned indirectlyby defoliation because of increased leaching fromdamaged foliage during rainfall (Schowalter and15 This section is based primarily on Wagner and McMillin

(1994).

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others 1986). Insect remains and frass also con-tribute to litterfall and may decompose faster thando fallen leaves and needles, which can result infaster cycling of elements such as calcium, potassi-um, nitrogen, and phosphorus (Haack and Byler1993, Schowalter and others 1986, Speight andWainhouse 1989).

One consequence of this increased cycling ofnutrients to the litter layer (in combination withchanges in the microclimate) may be compensato-ry growth after defoliation. Growth rates of matureDouglas-fir (Pseudotsuga menziesii (Mirb.) Fran-co) (Alfaro and MacDonald 1988), white fir Abiesconcolor (Gord. and Glend.) Lindl. ex Hildebr.)(Wickman 1980, 1986, 1988), and ponderosa pine(Pinus ponderosa Dougl. ex Laws.) (Miller andWagner 1989) increased after an initial decreasein growth after heavy defoliation by canopy herbi-vores. This effect was suggested to be a result ofchanges in soil nutrient levels or a thinning effect.The magnitude of this compensatory growthseems to be inversely proportional to the severityof defoliation (Alfaro and MacDonald 1988,Schowalter 1994).

Forest insects also act as pruning or thinningagents in the forest ecosystem, which may stimu-late growth and increase biomass turnover(Schowalter 1986, 1994; Velazquez-Martinez andothers 1992). Pruning or thinning of plant partscan stimulate plant growth by reducing competitionfor limited plant resources (Velazquez-Martinezand others 1992). Although insects and pathogenstypically remove less than 10 percent of foliageand shoots in nonoutbreak years, removal of theseplant parts apparently reduces plant metabolicdemands and facilitates reallocation of plant re-sources (Schowalter 1994).

Bark and ambrosia beetles begin a successionalprocess involving many species of arthropodsand micro-organisms that eventually results in thecomplete deterioration and recycling of the deadtree (see detritivory and nutrient cycling section).For instance, Tarsonemus endophloeus Lindquist,a phoretic mite associated with the western pinebeetle (Dendroctonus brevicomis LeConte) is re-sponsible for establishing colonies of the fungus,Ceratocystiopsis brevicomis, which is inoculated

ahead of the growing larvae and alters the phloemso the larvae can digest it (Hsiau and Harrington1997, Moser 1994, Moser and others 1995). InDouglas-fir, deterioration occurs at a slower rate ifthe Douglas-fir beetle (D. pseudotsugae Hopkins)and associated arthropods are excluded from deadbole sections (Edmonds and Eglitis 1989).

There are no empirical data indicating how impor-tant these herbivore-mediated effects on nutrientcycling are for the long-term productivity of forestecosystems. Growth responses of trees to theaddition of nutrients, in general, will only occurwhen growth at that site is nutrient limited (Speightand Wainhouse 1989). In other words, nutrient-poor sites may benefit most by high rates of nutri-ent cycling caused by defoliators. Likewise, inboreal forests, increased leaf-fall during outbreaksof defoliators will not provide an immediate in-crease of nutrients because of the slow rates ofdecomposition (Speight and Wainhouse 1989).

Succession relations—The effects of insects anddiseases on microclimate and water relations,nutrient and carbon cycling, and the direct re-moval of foliage cause changes in individual treegrowth and mortality. These effects are ultimatelymanifested at stand and ecosystem levels (Schow-alter and others 1986). Selective herbivory bymonophagous or oligophagous insects favors com-peting tree species and can result in a successionaltransition in stand age, composition, or density(Connell and Slatyer 1977, Haack and Byler 1993,Huffaker and others 1984, Klock and Wickman1978, Schowalter 1981, Schowalter and others1986). These changes, in turn, affect both produc-tivity and succession of the plant community (Huf-faker and others 1984). The rate and direction ofsuccessional change depends on the severity ofinfestation (for example, outbreak versus nonout-break populations), the type(s) of insects causingthe change (for example, tree-killers versus nonk-illers), single-species attack versus combined-species attack (for example, western spruce bud-worm, bark beetles, and pathogens), and the suc-cessional stage being infested (for example, standregeneration versus climax) (Franklin and others1987 from Haack and Byler 1993, Schowalter andothers 1986, Wulf and Cates 1985).

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Succession is typically accelerated toward theclimax species when there is low to moderateherbivory on dominant and codominant seral spe-cies. This alters competitive interactions amongtrees, thereby resulting in a reduced overstory andallows increased growth of shade-tolerant species(Connell and Slatyer 1977). An example of howcanopy herbivores can accelerate forest successionis western spruce budworm defoliation of seralhosts when nonhosts are climax (for example, low-elevation sites in the Blue Mountains) (Wulf andCates 1985). Tree-killing bark beetles can rapidlyfacilitate succession to shade-tolerant species onsites where hosts are seral.

Alternatively, herbivores may delay or even resetthe process of succession (Haack and Byler 1993).Western spruce budworm outbreaks tend to retardforest successional development on habitat typeswhere host trees are climax (Wulf and Cates1985). The loss of cone crops in combination withhigh mortality of young Douglas-fir and true firsencourages the regeneration of seral trees, and for-est succession may be effectively stopped by bud-worm (Wulf and Cates 1985). Bark beetles alsocan facilitate a return to seral forests. Mountainpine beetle killing of seral lodgepole often is fol-lowed by wildfire, leading to reestablishment ofseral lodgepole forests. In addition, secondaryinfestations by bark beetles may further rechargethe cycling nutrient pool, relieve moisture stress,and either keep or move the system toward ayounger seral state (Wulf and Cates 1985). Thebalsam woolly adelgid (Adelges piceae (Ratze-burg)), which can kill subalpine fir in 3 to 5 years,can significantly impact harsh sites such as lavabeds, talus slopes, and abandoned beaver marsheswhere subalpine fir is a pioneer species (Franklinand Mitchell 1967). Schowalter and others (1986)suggest defoliation on stressed trees accelerates themortality of such trees and releases competingvegetation. Stands composed largely of suitablehost trees often suffer extensive mortality of domi-nant and codominant trees. In such cases, ecologi-cal succession is typically reset to the early succes-sional stage (for example, grasses, forbs, andshrubs).

Defoliating insects may interact with fire as well aswith secondary attack by bark beetles to synergis-tically alter forest succession (Gara and others1985, Geiszler and others 1980, Hadley andVeblen 1993). For example, several studies suggestfire suppression in the Rocky Mountains since theearly 1900s may have led to increasingly severeand synchronous recurrences of western sprucebudworm by promoting dense, multistoried stands(Anderson and others 1987, Carlson and others1983, McCune 1983, Swetnam and Lynch 1989).Before fire suppression, it is believed small trees,seedlings, and saplings were eliminated by fre-quent, low-inten-sity fires, thereby decreasing theabundance of available hosts (Hadley and Veblen1993).

Ecosystem changes reflecting reduced canopycover have been suggested to occur earliest in theunderstory (Klock and Wickman 1978) and mayresult in increased plant and animal diversity(Schowalter and Sabin 1991). Zamora (1978)studied 98 grand fir (Abies grandis (Dougl.)Lindl.) stands in the Blue Mountains of Washing-ton and Oregon that had been defoliated 2 to 4years previously by Douglas-fir tussock moth. Hefound a small but significant increase in number ofmainly perennial grasses and forbs and up to a100-percent increase in total understory cover inseverely defoliated stands. Because many of theinsects feeding on understory plants are highly hostspecific, any increase in the diversity of grassesand forbs will increase their diversity as well, atleast temporarily. For a fauna of 302 species ofbutterflies and moths in the Blue Mountains,Grimble and others (1992) found that 44 percentfeed on understory hardwood shrubs, 43 percentfeed on forbs and grasses on the forest floor, andonly 10 percent feed on the canopy conifers.

Food source for other organisms—Forest herbi-vores are preyed on by various other arthropodsand vertebrates (Haack and Byler 1993, Martinand others 1951, Swan 1964). Arthropod preda-tors of defoliators include spiders, ants, true bugs,lacewings, snakeflies, beetles, flies, and wasps(Torgersen 1994). Much of the earliest research onpredators of Douglas-fir tussock moth and westernspruce budworm was done in east-side ecosystems

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(Torgersen 1994). For example, over a dozen spe-cies of forest-dwelling ants prey on western sprucebudworm and Douglas-fir tussock moth. Manyarthropod species have been used in biologicalcontrol programs against tree-feeding insects(Haack and Byler 1993).

Of animals other than arthropods, birds probablyconsume the most tree-feeding insects (Haack andByler 1993). Increases in woodpecker populationshave been observed in areas with high bark beetlepopulations (Koplin 1969). Torgersen and Torgers-en (1995) observed at least 35 species of birds thatfeed on the western spruce bud-worm and Dou-glas-fir tussock moth in east-side ecosystems. Twospecies, mountain chickadee (Parus gambeli) andred-breasted nuthatch (Sitta canadensis), how-ever, dominated observations of actual predationon the western spruce budworm and Douglas-firtussock moth and were the most numerous species(Langelier and Garton 1986, Torgersen and others1984). Most mammals, both large and small, con-sume insects to some degree (Haack and Byler1993), and they, in turn, may be eaten by second-ary predators.

Creation of, or effect on, wildlife habitat—Treeskilled by insects are used as wildlife habitat both asstanding snags and when they fall as downedwoody material (Maser and Trappe 1984). At least270 species of North American reptiles and am-phibians, 120 species of birds, and 140 species ofmammals use deadwood to roost, nest, or forage(Ackerman 1993). Wildlife needs for plant com-munities, successional stages, and forest edges allare affected by the activities of insects (Thomasand others 1979). In areas where cover is plentifuland forage is limiting, the increase in forage plantbiomass 2 to 4 years after severe defoliation willhave a positive influence on deer and elk use (Th-omas and others 1979). Down woody debris isalso a critical resource for invertebrates (Harmonand others 1986).

The effects of severe defoliation and tree mortal-ity will differ depending on the habits of wildlifespecies. Species that normally occupy the upperhalf of the tree crown will be detrimentally affect-ed by severe defoliation for 1 or 2 years. In gener-al, however, insect damage that causes small

patches of snags or more open stands will create amore diverse habitat, benefitting the bird commu-nity (Klock and Wickman 1978).

Pollination—Moths and butterflies are among theinsect herbivores that as adults are pollinators.Several hardwood tree species, as well as many ofthe understory herbs and shrubs rely on insects fordispersal of pollen (see “Pollinators” section for amore detailed description of this function).

Watershed properties—Alterations in vegetativecover resulting from forest herbivory can affectthe quantity and timing of streamflows. Bark bee-tle-caused tree mortallity can significantly increasewater yields, and the effects can last up to 25years (Bethlahmy 1975, Love 1955, Mitchell andLove 1973, Potts 1984). These effects apparentlyare due to reduced interception and evapotranspi-ration. In addition, peak flows may be higher andoccur earlier in the season after bark beetle infesta-tions (Cheng 1989, Potts 1984). Forest herbivorycan change the biological communities withinstreams and the physical structure of stream chan-nels through effects on riparian vegetation anddetrital inputs.

Fuel conditions and fire hazards—Fire hazardsmay increase significantly after insect infestations.In the Canadian province of Ontario, repeated de-foliation by the eastern spruce budworm causedhigh rates of mortality to balsam fir (Abies bal-samea (L.) Mill) (Stocks 1987). Surface fuel loadsand fire hazards increased for 5 to 8 years afterbudworm-caused mortality as the dead trees brokeapart and fell to the forest floor. Fire potentialsgradually declined after 8 years as the surface fuelsdecomposed and vegetation became established onthe sites. Twenty years after a spruce beetle out-break on the Kenai Peninsula, there was signifi-cantly more sound, dead wood >7.5 centimeters indiameter compared to uninfested areas (Schulz1995). In addition, there was significantly greatercover of bluejoint grass (Calamagrostis canaden-sis (Michx.) Beauv.), a fine, flashy fuel that facili-tates rapid fire spread. The combination of finefuels and sound, woody material created condi-tions for intense and unpredictable fire behavior.

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Implications of management for invertebrateforest herbivores16—Forest management primari-ly affects forest herbivores in two ways—throughoverstory host plants and understory host plants.

1. Overstory host plant availability and suit-ability. The principal way management activitiesaffect canopy and bole herbivores is throughchanges in their food source, host trees. Standtraits includ-ing species composition, tree age andsize, stand structure, and stress act independentlyand in concert to affect the composition and rela-tive abundance of this herbivore guild.

Species composition—Tree herbivores are largelymonophagous or oligophagous (Strong and others1984). Consequently, most herbivore populationsand ranges are defined by their forest tree hostsand are relatively well known (Furniss and Carolin1977). This ecological specialization suggests ahigher probability of canopy and bole herbivoresbeing affected by management practices (for ex-ample, prescribed burning, thinning, selectiveharvest, and regeneration) affecting their hosts.Because of their host specificity, insect herbivorediversity will increase with a greater diversity ofcanopy species of trees. The guild of predatorsand parasites also will increase. Changes in treecomposition will cause sudden impacts on herbi-vores, and probably will persist for a long time.Preventing large contiguous areas of host type(tree species and size) will minimize the probabilityof widespread outbreak of indigenous defoliatorsand bark beetles as well as accidentally introducedexotic species.

Tree age and size—Age and size-class distributionof hosts also govern abundance of canopy andbole herbivores. Many herbivores have specializedto feed on trees at different stages in maturationdevelopment (Nielson and Ejlersen 1977, Schow-alter 1985). For bark beetles, tree species compo-sition is important during stand development frompole to larger tree sizes because these are the treesizes that are suitable hosts. For example, Dunbarand Wagner (1990) and McMillin and Wagner

(1993) recognized that three species of pine saw-flies, Neodiprion gillettei (Rohwer), N. fulviceps(Cresson), and N. autumnalis Smith, feed on foli-age of seedlings, young pole-sized trees, and pole-sized to mature trees of ponderosa pine, respec-tively, in the same geographical area. Managementactions like prescribed fires, thinning, harvest, andregeneration, that change the age or size-class dis-tribution of hosts can potentially change the popu-lations of associated herbivores. Generally, defolia-tor outbreaks will have the greatest effect onstands beginning from the stem-exclusion stage.Maximum diversity of herbivores and minimumoutbreaks of individual species will be obtainedunder those management scenarios that mix age-and size-class distributions, other stand factorsbeing equal.

Stand structure—Many aspects of forest structureincluding density, vertical diversity, understoryvegetation, forest successional stage, and presenceof coarse woody material will influence the treeherbivore community. Variation in forest structuredecreases the apparency of forest resources to for-est insects (Schowalter 1986). This occurs throughmodification of the proximity of insects to suitableresources, cues used by insects to orient to hosts,and forest microclimate. All these factors increasethe functional diversity of the forest and conse-quently increase diversity of the canopy and boleherbivore community but likely decrease totalpopulations of any individual herbivore species.

Stand density becomes an important factor in barkbeetle population dynamics as trees reach pole sizeand larger; trees growing on drier sites will becomesusceptible to beetle infestations at lower densitiesthan those growing on moister sites. The longerdense pole size or larger stands persist, the greaterthe probability they will become infested by barkbeetles. Management activities that reduce standdensity such as thinning and prescribed burningcan reduce the probability of bark beetle infesta-tions. Although canopy density may influencedefoliator populations less than bark beetles, standdensity can affect the population dynamics ofwestern spruce budworm (Wulf and Cates 1987)and pine sawflies (McMillin and Wagner 1993,1998).

16 This section is based on discussions during the expert panelon forest herbivores (see appendix 1) and Wagner andMcMillin (1994).

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Forest successional stage is potentially importantto canopy herbivore abundance. As successionprogresses, forests become more diverse (Hansenand others 1991) and create more ecological nich-es, which in turn support greater diversity of cano-py herbivores (Warren and Key 1989). In general,mature forests tend to be dominated by defoliatingcanopy insects, whereas young forests are domi-nated by sapsucking insects (Schowalter andCrossley 1987). Schowalter (1989) examined thecanopy arthropod community structure in forestsin various successional stages and concluded thatold-growth forests supported substantially morespecies and functional diversity in canopy herbi-vores than did young regenerating forests. Thegreater diversity of canopy herbivores in late-successional forests implies that these forests con-tribute disproportionately more to total canopydiversity than do younger forests. Hence this rep-resentation on the landscape should be dispropor-tionately higher than the other species if theobjective is to maximize species diversity of cano-py herbivores. Management activities that reducelate-successional forest likely will reduce diversityof canopy herbivores.

Hypothetically, more coarse woody material couldindirectly reduce the frequency of defoliator out-breaks owing to increased population densities ofant predators. A confounding factor is that if antnumbers are reduced, other predators compensatefor them (Campbell and others 1983).

Coarse woody material (standing and down) issuitable as a breeding site for bark beetles for 1 to2 years after tree death. Beetle populations canincrease in woody material, disperse, and then (ifabundance is sufficient) cause significant mortalityof standing green trees. Trees that die in late sum-mer through spring (after dry weather and beforebeetle flight) will be most suitable for bark beetleinfestation in most habitats. Possible actions tomitigate bark beetle buildup in woody material areto modify time of felling (to allow slash to drybefore subsequent beetle flight), remove or burnwoody material infested by beetles, or use semio-chemicals to prevent infestations in dead and downmaterial.

Stress—Stress to trees usually occurs over rela-tively short periods, one to several years. Somecauses such as overstocking, understory density,drought, or defoliation, however, can develop overperiods of 5 to 10 years or longer. Likewise, miti-gation of the attraction of bark beetles to stressedtrees can utilize either short-term control strategies(for example, removal, burning of diseased anddamaged trees, or protection by using semiochemi-cals) or long-term management actions (for exam-ple, regulate stand density, minimize damage totrees during intermediate stand treatments, matchtree species to site conditions, and manage thedensity of understory competition). Although somedefoliators seem to respond to short-term treestress with population increases, stress probablydoes not generate large outbreaks of defoliators.Low levels of stress over short periods probablyhave little or no impact on canopy defoliators.

2. Understory host plant availability. Manage-ment practices affect understory herbivores inseveral ways: (a) indirectly through changes in thedensity of the overstory canopy, which influencesthe type and abundance of understory plants; (b)indirectly through manipulations of the understoryvegetation; and (c) direct mortality caused byapplication of insecticides for overstory defoliators.Changes in the understory herbivore guild will af-fect plant community dynamics and predators andparasites that use these species as prey or hosts.

Changes in overstory canopy density—Openingup the forest canopy will promote greater forb andgrass growth for understory herbivores, which inturn support predators and higher levels of thefood web. Selective thinning of overstocked coni-fer stands would open the forest for more an-giosperms and therefore promote these understoryspecies.

Manipulation of the understory vegetation—Although a certain level of disturbance mayenhance herbivore diversity in the understory,excessive use of any approach on a large spatialscale will result in a depauperate flora and fauna.Periodic ground fires keep the forest floor openwith plenty of light to encourage the growth of

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forbs, grasses, and shrubs, which in turn supportdetritivores, herbivores, and their predators. In theabsence of such fires, dense stands of young firand pines become established and shade out theangiosperms and thus reduce the diversity of theassociated herbivores. Controlled ground fireswould mimic naturally occurring fires. Cool tomoderate intensity burns likely would be best be-cause of the role litter and soil organisms play inproductivity of the site. Overgrazing, scarifica-tion, and the use of herbicides all will reduce an-giosperm growth, and likewise reduce the abun-dance and diversity of the understory fauna.

Application of pesticides—Some research17

shows a 66-percent loss of species, 85-percent lossof individual abundance, and a 95-percent loss inbiomass of understory Lepidoptera after applica-tion of Bacillus thuringiensis kurstaki (B.t.k.) forthe western spruce budworm. This is not unex-pected because B.t.k. can kill many of the mothsor butterfly species that ingest it. Impacts on non-target herbivores are expected to last from 1 to 3years depending on the number of applications andthe size of the area sprayed. The more frequentthe treatments, the greater the impact. The largerthe size of the spray area, the longer it will takefor recolonization from untreated areas. If a sprayarea includes habitats not otherwise representedin the vicinity, species specific to those habitatswould be the most adversely affected.

General implications of management practiceson invertebrates—In general, because currentconditions in many of our ecosystems have beenmodified so significantly by fire suppression, graz-ing, and the introduction of exotic species such aswidespread plantings of Agropyron sp., a simplereversal of fire management by using prescribedburning may not accomplish an objective of re-turning the land to its previous condition. Thus,prescribed burning needs to be used with extremecaution, generally with native species in mind.

Overgrazing of shrub-steppe, prairie, savannah, ormountain meadows can eliminate arthropod spe-cies by conversion of perennial grasses, nativeforbs, and shrubs to introduced annuals. Maintain-ing native plant communities would foster nativearthropod species.

Recreation can damage arthropod habitat throughtrampling or road building. Probably the mostcritical habitat in this category is caves, where afew unusual arthropod species live. Excessive traf-fic within caves, even from directed recreationaluse, can cause faunal deterioration. Other vulnera-ble areas are bogs and hot springs.

Exotic species can profoundly affect arthropodfauna. Exotic plants, or arthropods introduced asbiological controls of pest species or as pollinatorsmay competitively displace native species that areimportant to beneficial predators or other function-al groups.

Invertebrate BiodiversityAccording to Asquith and others (1990), arthro-pods represent 86 percent of the biota of an old-growth forest (H.J. Andrews Experimental Forest)when all vertebrate species and all vascular plants,and the then-known number of insects and otherarthropods were compared. Over 3,400 species ofarthropods were known then, a number approach-ing 4,000 species today. According to Wilson(1988), over 950,000 species of insects have beendescribed—the most species of any group. Ulti-mate numbers range from 5 to 30 million species,depending on new forecasts. Large parts of ourinvertebrate fauna are poorly known, particularlyin the tropics, but better known in temperate re-gions. Some species are known chiefly from theoriginal descriptions and perhaps other localities.Our knowledge of temperate fauna is far better,although there are some groups that are poorlyknown because we have fewer systematists avail-able to work on many of these groups. A renais-sance is needed in most areas of systematics if weare to be able to develop adequate databases inspecies recognition, distribution, and habits toprovide proper information to land managers. Atpresent, support for such individuals lags far be-hind other areas.

17 Unpublished data. On file with: Jeffrey Miller, Professor,Department of Entomology, Oregon State University,Corvallis, OR 97331.

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No thorough survey is available of all species inthe basin assessment area; we can only infer fromwhat is known elsewhere that the number of spe-cies here is large. Table 1 gives a perspective ofhow great invertebrate diversity may be worldwideand how it relates to the diversity of other taxa. Atotal of 14,439 species is estimated to inhabit thebasin assessment area based on described species.Most of the catalogued taxa are vascular plantsand allies (about 10,191 taxa or 71 percent) andarthropods (about 3,400 known taxa or 24 per-cent), mostly insects (table 2). Only a few (609taxa or 3 percent) are vertebrates. The number ofestimated taxa (excluding micro-scopic life forms),with extrapolations for species not yet described,totals over 35,200 species (table 2). Estimatednumbers of macroinvertebrates dominate this sum(24,290 estimated taxa or 69 percent), with plantsand allies second (10,340 estimated taxa or 29percent). We assume the vertebrate species of thebasin assessment area, where considerable re-sources have been spent, have been fully de-scribed (609 taxa or 2 percent).

Approaches to ManagingInvertebrate BiodiversityCan and should invertebrate diversity be managedby using the same tenets used for vertebrates andplants? Indeed, is this philosophy working forvertebrates and plants? Will a species-by-speciesapproach adequately protect most rare and ende-mic invertebrate species? What does such anapproach mean with regard to the feasibility ofcomplying with the Endangered Species Act, andwhat does it mean to the implementation of eco-system management? In our effort to gather infor-mation about the invertebrate fauna of the basinassessment area, we contracted with various ex-perts who differed widely both in their disciplinesand in their viewpoints of invertebrate diversity.In the following sections, we describe several ap-proaches to managing invertebrate diversity. In-cluded are possible implications of these ap-proaches to general biodiversity conservation andto the implementation of ecosystem management.

Table 1—The diversity of organisms worldwide

Number of speciesCurrently Number including

Taxonomic group described undiscovered species

Plants and allies:Algae 40,000 200,000 to 10 millionFungi 70,000 1 to 1.5 millionPlants 250,000 300,000 to 500,000

Invertebrates:Protozoans 40,000 100,000 to 200,000Viruses 5,000 perhaps 500,000Bacteria 4,000 400,000 to 3 millionRoundworms 15,000 500,000 to 1 millionMollusks 70,000 200,000Insects 950,000 8 to 10 millionSpiders and mites 75,000 750,000 to 1 millionCrustaceans 40,000 150,000

Vertebrates 45,000 50,000

Source: Wilson 1988; undiscovered from various sources.

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Single-species approach—This is the modelcurrently followed with the designation of FWSthreatened and endangered species and FS- andBLM-sensitive species. Designations are based oncriteria such as rareness, limited distribution, andpresent or probable threats to a species’ habitat.

Certain invertebrate groups, those that are lessdiverse and have a solid base of information abouthabitat needs, will be more amenable to a single-species approach. Major difficulties in attemptingto assign threatened and endangered status to in-vertebrates are due to the emphasis on large char-ismatic organisms and the apparent lack of publicinterest.

Given that species are continually being addedto lists of special concern, what are the implica-tions of the vast undescribed diversity of insects?What do extensive lists of sensitive plants, snails,and fungi imply about those taxa yet to be as-sessed in this manner? There is little reason todoubt similar work on arthropods or micro-organisms would yield long lists of similarlysensitive species. Providing preserves for everysensitive organism would soon become impossible,and we are left with the question of how to dealwith the potentially conflicting requirements ofdifferent sensitive species at a single location.

Formal listing or even recommendations for addi-tional monitoring and surveys almost always hasenormous economic, political, and social implica-tions. The promotion of threatened and endan-gered species by either individuals or agencies hasobligations, not the least of which is maintainingthe credibility of threatened and endangered list-ings. The designation of candidate species aboutwhich virtually nothing is known or that are basedsolely on single collecting events are problematic.“Rare” species have too often been found to berelatively abundant or widespread, because theywere cryptic, restricted to poorly accessed or “un-interesting” habitats, required special collectingtechniques, or were simply not actively sought inthe past (LaBonte 1995).

Although still working within the single-speciesapproach, a more conservative plan has beenadvanced by many arthropod specialists. Theirconcern is that given the anomalies of collecting

stated above, a relatively high degree of knowledgeshould be required before putting species on lists.In other words, to list a species as one of specialconcern, we should understand its distribution andrequirements. The following are only a few exam-ples of criteria to consider in determining whichinvertebrate species are deserving of special status(LaBonte 1995):

• The species is known from more than onecollecting event.

• Evidence exists that the species is restricted topotentially threatened or patchily distributedhabitat.

• Evidence exists that the species has a restrictedgeographic distribution.

• Evidence exists that the species has poordispersal capabilities.

• Habitat threats can be managed or mitigatedwith known technologies.

A rule set could be used to determine which com-bination of these criteria would be required. Evalu-ation of whether a species meets the criteria couldbe judged by an unbiased panel of experts. Toensure a qualified but unbiased examination, thepanel could include at least one expert from thetaxonomic group under consideration, and theremainder of the panel members would have simi-lar expertise but with unrelated taxonomic groups.

Unique-habitats approach—Preservation of rarehabitats will result in the support of many rare spe-cies. Areas such as sand dunes, lava flows, moun-tain meadows, bogs, hot springs, and caves likelywill encompass many of the species already occur-ring on lists (for example, the FWS candidate spe-cies of beetles Agonum belleri Hatch, Cicindelaarenicola Rumpp, Glacicavicola bathyscioidesWestcott, and the skipper Polites mardonEdwards), as well as more rare species that will berecognized once these areas are adequately sur-veyed. Many of these unique habitats are relativelysmall, have low economic value, and some ofthem (such as those within national parks andwilderness areas) are already protected. Selectionof patchy areas could be by local personnel whoknow the locations of such unique communities.

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Table 2—Counts or estimates of total species biota of the basin assessment areaa b

Total in basin Number consideredTaxonomic group Known Estimated in assessment

Plants and allies:Fungi 394 394Lichens 736 736 736 (39 grpc)Bryophytes 811d 860 811 (11 grp)Vascular plants 8,250 8,350 8,078

Total 10,191 10,340 10,019 (50 grp)Invertebrates:

Protozoa ?e ? 0 (1 grp)Rotifers ? ? 0 (1 grp)Nematodes ? ? 0 (3 grp)Mollusks 380f 790 380Insectsh 3,400 23,500 335

Total 3,780 24,290 715 (5 grp)Vertebrates:

Fish (natives) 87 87 87Fish (exotics) 54 54 54Amphibians 26 26 26Reptiles 27 27 27Birds 283 283 362Mammals 132 132 132

Total 609 609 688Total, all taxa 14,580 35,239 (61 grp) 11,422 (143 grp)

a Viruses, algae, phytoplankton, zooplankton, and most aquatic arthropods are not included in this table. Fungi numbers hererepresent macrofungi. See text for discussion of microfungi, bacteria, protozoa, and nematodes.

b Figures are number of taxa (mostly species with a few subspecies of particular conservation concern).

c grp = a group of similar species. The group is based on taxonomic or ecological function similarity.

d Christy and Harpel (1995).

e These groups are not well enough known to estimate their numbers.

f The 380 known mollusks include 200 freshwater gastropods, 30 freshwater bivalves, 25 slugs, and 125 land snails (Frest and Roth1995).

g The 790 suspected mollusks include 445 freshwater gastropods, 35 freshwater bivalves, 30 slugs, and 280 land snail (Frest andRoth 1995).

h Insects (Lattin 1995a).

g

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Centers-of-endemism approach—For a few taxa(butterflies, for example) areas of endemism havebeen identified, but no attempt has been made todefine areas of coincidence for endemism. Mol-lusks are one exception, with some endemic cen-ters recognized since the 1860s (Frest andJohannes 1995). At least 12 such endemic centersare recognized by Frest and Johannes (1995) with-in the basin assessment area. The spatial and geo-graphic features that lead to endemism in higherplants, however, generally are known and may, asa starting point, be hypothesized to be the same asthose used by herbivorous invertebrates. Examplesof possible centers of endemism are the BlueMountains, which represent a potential suture zonebetween the Cascade-Sierra and Rocky Mountainfaunas, and the Steens Mountains, which mayserve as islands fostering genetic diversification.

Representative-habitats approach—The pur-pose of retaining areas with representative vegeta-tion communities and habitats is to maintain thecommon native fauna, which account for mostof the invertebrate species. Research natural areasand similar existing special-use areas could be usedin preserving representative habitats.

Centers-of-biodiversity approach—Centers ofhigh invertebrate diversity may be caused by threedistinct phenomena: (a) areas of palaeoendemism,(b) areas of rapid recent evolution, and (c) areas ofhigh geographic microclimatic heterogeneity. Onthe west side of the crest of the Cascade Range,the Siskiyou Mountains are well known as centersof palaeoendemism. Our knowledge of such areasin the Columbia River basin is rudimentary. Frestand Johannes (1995), however, do recognize sev-eral such areas for mollusks and specify the geo-logic and historical phenomena likely responsible.The best example is the Lower Salmon River-HellsCanyon area of Idaho, Oregon, and Washington.The alpine altitudinal islands of the basin assess-ment area may represent such areas. Several en-demic carabid beetle species are known from suchaltitudinal islands as the Wallowa and SteensMountains (LaBonte 1999). Present knowledge of

areas of recent speciation is incomplete. In theabsence of strong examples of the first two phe-nomena, the most likely correlate of high localizedinvertebrate diversity may be heterogeneity of thegeologic substrate (that is, a diversity of elevations,aspects, life zones, and plant associations). If thisis true, it would be relatively easy to locate geolog-ically or botanically heterogeneous regions. Anoversight panel could select the combination ofareas that best ensures all biogeographic typesacross the basin assessment area are represented.

Towards an Approach forConservation of InvertebratesOne or several of the above approaches could beapplied to a plan to conserve invertebrate diversity.The most fundamental decision in devising such aplan is whether a species-specific or habitat-focusapproach, or some combination thereof, is war-ranted.

A species approach would entail the need for spe-cial management restrictions for all land wheredesignated species of special concern occur. Hereagain, the question is what criteria are species listsbased on, and how extensive can these lists getbefore such a strategy is inoperable? Another con-cern is that such an approach protects rare andendemic species, which can be a small proportionof total species diversity with restricted distributionand may fail to protect key contributors to impor-tant ecosystem functions such as nutrient cycling,pollination, herbivory, and predation over a broadgeographic area. A possible disadvantage of aspecies-specific approach is that it does not em-phasize habitats and may be a roadblock to thestudy of arthropod function.

The last four approaches are aimed at conservingdiscrete habitat units on which the primary man-agement goal would be the general (not species-specific) maintenance of biological diversity. Thehope is that a combination of these different typesof habitat conservation areas would provide pro-tection for most invertebrates.

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Invertebrate Species ofConservation InterestRare or Sensitive InvertebrateSpeciesFederally listed endangered or threatened spe-cies—Currently no terrestrial invertebrates in thebasin assessment area are federally listed as endan-gered or threatened.

Federally listed candidate species—There are 15terrestrial invertebrates that, before 1996, wereFWS federal candidate 2 species18 (table 3).

Arachnida, Pseudoscorpionida:

Apochthonius malheuri Benedict and Malcolm(Chthoniidae). The only known population of thisspecies occurs in Malheur Cave, a lava tube about1000 meters long, in Harney County, Oregon.Many other caves have been surveyed, but thisspecies has not been found elsewhere. MalheurCave is unique as the terminal third of the lavatube contains a geothermal lake, which modifiesthe microclimate. Apochtonius malheuri appearsto be cave adapted as it has morphological charac-teristics such as a thin integument and an elongatedbody. Adequate moisture levels are necessary forthis species, thus it occurs within a band from 168to 381 meters from the mouth of the cave, de-pending on the level of the lake. Apochtoniusmalheuri is a predator, preying on springtails,mites, spiders, and other terrestrial microarthro-pods. Habitat needs include material such as woodchips or other materials that small animals and batsmay bring into the cave and the warm environ-ment provided by this thermal cave (about 10degrees higher than average surface annual tem-perature). Apochtonius malheuri naturally occursat low population levels because of its limited

habitat. The population is stable, with all threenymphal stages and both males and females foundin a 1994 survey. Although both the cave and thisspecies are presently stable, possible threats to thecave and to A. malheuri are pesticide drift fromnearby agricultural fields; drought or agriculturaldrawdown of water, either of which could cause areduction in the level of the lake; heavy human useof the cave; and the introduction of exotic organ-isms via wood chips (brought into the cave by agroup that owns the outer portion of the cave anduses it regularly) that may outcompete the endemiccave species. A status report by Benedict andMcEvoy (1995) is available.

Gastropoda—

Cryptomastix magnidentata (Pilsbry) (Poly-gridae). Scattered colonies occur along one side ofa half-mile stretch of Mission Creek, Idaho. Thespecies lives in moist, rocky, well-shaded forestwith common forbs and deciduous trees, and inmoist and mossy, rather open grassy limestone andmixed limestone-basalt taluses a short distanceabove the flood plain of Mission Creek. Much ofthe type area has been destroyed or greatly modi-fied because of limestone quarrying, which hasproceeded sporadically and is ongoing. Sites arealong the present quarry haul road, which has sub-stantially impacted taluses in the area. Portions ofthe quarry area also have been heavily grazed, andmuch of the upland in the immediate vicinity hasbeen logged. The species is absent from theseareas and is evidently declining in numbers andarea occupied; population trends are downward.Based on recently collected information and sur-vey work, Frest and Johannes (1995) recommendthis species be listed as endangered on the federallist of endangered species and in the state of Ida-ho; they recommend it be considered a sensitivespecies by the FS, BLM, Nez Perce Tribe, andother appropriate land and wildlife managementagencies.

Discus marmorensis Baker (Discidae). This spe-cies occurs as a few colonies in central portions oftwo creek tributaries to the lower Salmon River inIdaho. It is generally found at moderate elevationson limestone terrain in relatively intact, moist,well-shaded (closed to nearly closed-canopy) pon-derosa pine forests, with diverse deciduous and

18 On February 28, 1996, the USDI Fish and Wildlife Servicepublished in the Federal Register a change in their speciesstatus program, essentially replacing the three candidatespecies categories with a single category. In this change, mostof the species that were classified as category 2 or 3, and 303taxa that were category 1 candidates, are no longer included inthe list of candidate species. Our report retains the category 2listing for two reasons: (1) the data collection preceded theruling change, and (2) the category 2 designation denotesspecies of potential conservation concern deserving attention.

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forb understory. The species occasionally occursin moist schist talus in such forests. In both cases,snail colonies are generally near stream edges andat the base of steep slopes. Much of the originalarea of occurrence has been logged and is nowheavily grazed; the species is absent from suchareas. Limestone quarrying has eliminated much orall of one colony in the last 3 years. Roads into thearea generally are situated to fragment or eliminatecolonies. Population trends are downward. Basedon recently collected information and survey work,Frest and Johannes (1995, 1997a) recommend thisspecies be listed as endangered on the federal listof endangered species and by the state of Idaho;they recommend it be considered a sensitive spe-cies by the FS and BLM.

Monodenia fidelis minor Binney (Brady-baenidae). This subspecies survives in a few colo-nies in the mouth of and in the lower DeschutesRiver valley, Oregon, and near Dog Falls, Wash-

ington (Frest and Johannes 1995). Most knownsites are in the Columbia River Gorge NationalScenic Area. The species has been observed tooccur at some sites with the Larch Mountain sala-mander (Plethodon larselli Burns). It is generallyin basalt talus, often north-facing, often associatedwith seeps and springs. Road building and modifi-cation have destroyed or fragmented some colo-nies. Much of the original range is heavily grazed.

Oreohelix idahoensis idahoensis (Newcomb)(Oreohelicidae). This subspecies is restricted to afew colonies in a small area a few miles along bothsides of the lower Salmon River, Idaho. It is re-stricted to low-middle elevation limestone andcalcareous schist outcrops and talus, generally insage scrub. Grazing, gold mining, talus and lime-stone quarrying, and range fires pose threats to thisspecies. One large colony is now near extinctionbecause of a combination of grazing and recent

Table 3—The USDI Fish and Wildlife Service (FWS) former federal candidate 2 species andBureau of Land Management (BLM) sensitive species

FWS BLMClass and order Genus and species candidate 2 sensitiveArachnida, Pseudoscorpionida Apochtonius malheuri Ca

Gastropoda Cryptomastix magnidentata CDiscus marmorensis CMegomphix lutarius CMonadenia fidelis minor C COreohelix idahoensis idahoensis COreohelix jugalis COreohelix strigosa delicata COreohelix strigosa goniogyra COreohelix vortex COreohelix waltoni C

Insecta, Coleoptera Agonum belleri CCicindela arenicola CGlacicavicola bathyscioides CNebria gebleri fragariae CNebria vandykei wyeast C

Insecta, Lepidoptera Charidryas acastus dorothyea CLimenitis archippus lahontani CPolites mardon C

Insecta, Orthoptera Acrolophitus pulchellus C

a C = candidate before 1996.

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fires. In one area, sheep grazing has eliminatedmost of one colony, whereas remnants on theopposite side of the road (protected from grazing)have abundant snails. Frest and Johannes (1995,1997a, 1997b) recommend listing as threatened onthe federal list of endangered species, and by thestate of Idaho; they recommend it be consideredsensitive by the FS, BLM, and other land manage-ment agencies.

Oreohelix jugalis (Hemphill) (Oreohelicidae). Thisspecies survives at some sites along the lowerSalmon River, Idaho. It occurs at low elevation inrock taluses and boulder piles. This is a rathertolerant species, occupying the range from slightlymesophile to moderately strongly xerophile. Nearlyall known sites are impacted by grazing; sheep,horses, and cattle have considerably reduced oreven extirpated colonies. Road construction andmaintenance have considerably reduced or extir-pated the species from much of the corridor alongUS Highway 95. Talus mining has affected talusesin the immediate vicinity of all sites. Gold miningand prospecting impact sites in schist lithologies.Population trends are clearly downward. Withthorough survey, O. jugalis has been noted asmore common than originally expected, eventhough it has suffered considerable range and siteloss. Frest and Johannes (1995, 1997a) suggestplacing this species on a “watch” list. If sites forother more rare species in the same corridor canbe pro-tected, it is possible this species will beadequately protected. They feel it should be con-sidered sensitive by the FS, BLM, and other landmanagement agencies; and if other species are notprotected, it should be listed as threatened on thefederal list of endangered species.

Oreohelix strigosa goniogyra Pilsbry(Oreohelicidae). This subspecies may be limited toa few remnant colonies in the Race Creek drainagein Idaho. This snail is found mostly on outcropsforested with ponderosa pine. Commonly, siteshave a partly to completely closed canopy anddiverse forb and deciduous understory. Threatsinclude grazing, logging, road location and modifi-cations, and forest fires. Based on recent surveys,Frest and Johannes (1995, 1997a) recommend thistaxon be listed as endangered on the federal list of

endangered species and by the state of Idaho; theyrecommend it be considered a sensitive species bythe FS and other land and wildlife agencies.

Oreohelix vortex Berry (Oreohelicidae). This spe-cies remains in a few isolated colonies in the mostundisturbed parts of the northern portion of thelower Salmon River valley in Idaho. It is restrictedmostly to large-scale basalt taluses. Sites are typi-cally dry and open, the most common vegetation isgrasses. The species prefers low to medium eleva-tions in large stream valleys. Threats include heavygrazing occurring in much of its range; talus miningin the lower Salmon River valley, which recentlydestroyed some old sites; and highway construc-tion and maintenance. Recent surveys of the arealead Frest and Johannes (1995, 1997a) to recom-mend listing as endangered on the federal list ofendangered species and by the state of Idaho andsensitive status by the FS and other federal andstate land and wildlife agencies.

Oreohelix waltoni Solem (Oreohelicidae). Thisspecies survives in perhaps four sites near Lucileand John Day Creek, Idaho. It is found in dry,open areas in sage scrub vegetation. All knownsites are impacted by grazing. Road constructionand maintenance have considerably reduced thesite along US Highway 95. Talus mining, especial-ly for basalt gravel, has affected taluses in the im-mediate vicinity of all sites. Gold mining andprospecting impacts sites in schist lithologies.Recent surveys lead Frest and Johannes (1995,1997a) to strongly recommend listing as endan-gered on the federal list of endangered species andby the state of Idaho and sensitive species designa-tion by the BLM, FS, and other land managementagencies.

Insecta, Coleoptera—

Agonum belleri Hatch (Carabidae). This spe-cies has been recorded in southwestern BritishColumbia, northernmost Oregon (Mount Hood)just east of the Cascade crest, and western Wash-ington from the eastern Puget Sound to the Cas-cade Range. The Oregon sites are just at thewestern margin of the basin assessment area.Agonum belleri is restricted to sphagnum bogs(Sphagnum magellanicum Brid. and

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S. squarrosum Crome) from sea level to 1050meters. Preferred habitat appears to be the mar-gins of bogs with open water and floating mats ofsphagnum. Bogs without open water but with matsof sphagnum resting on a solid substrate are lessfavored, as is sphagnum in forest-open area eco-tones. Circumstantial evidence suggests that A.belleri may be able to survive in sphagnum seeps,but this is presumably marginal habitat. Adult A.belleri are short-winged and incapable of flight, soall dispersal is by adult and larval walking. Al-though potentially suitable habitat is widely scat-tered along both sides of the Cascade crest (as wellas a few remaining lowland bogs), accessible habi-tat must presumably be essentially contiguous toexisting A. belleri populations. Historically, theoverall population has declined because of habitatdegradation and destruction, particularly in thePuget Sound area. Potential threats are drainageand filling of sphagnum bogs, trampling, sphagnumbog succession, and forestry use of insecticides.LaBonte (1995) suggests that continuing habitatdestruction and degradation, strong stenotopy,presumably limited dispersal capabilities, andpatchy habitat distribution all point to a species atrisk of extinction and that is clearly threatened orendangered.

Cicindela arenicola Rumpp (Cicindelidae). Thisspecies is presumably restricted to sand dunes orsandy areas with sparse vegetation (no more thanabout 30 percent cover) and ranging in elevationfrom about 750 to 1700 meters in southern Idaho.The larvae are found in mildly sloping or flat,stable dune or sandy areas, whereas the adults aremore broadly distributed throughout dune-sandyareas. The range of effective adult dispersal (viaflight) may be no more than roughly 1 kilometer;larval dispersal (via walking) is probably limited toa few tens of meters. Potentially suitable habitat iswidely scattered throughout much of southernIdaho. Habitat degradation through various agentsis the greatest threat to C. arenicola. Disruption ofthe dune and sand substrates by human and live-stock trampling and by off-road vehicles maydirectly destroy young larvae and collapse tunnelsof older larvae. Intentional stabilization of dunes

by grass seeding would completely eliminate habi-tat, and there is evidence that introduced weedsare encroaching on and degrading habitat at onesite. The more stable and flat larval habitat is par-ticularly susceptible to the latter influence. Range-land pesticide applications are obvious potentialthreats to this species. LaBonte (1995) suggests itsnarrow habitat restrictions, patchiness of suitablehabitat, and apparent sensitivity to habitat disrup-tion renders C. arenicola as a candidate for threat-ened and endangered status, although suggestingmore information about its habitat restrictions andoverall distribution should be obtained beforemaking this decision.

Glacicavicola bathyscioides Westcott(Leiodidae). This species is known only fromsouthern Idaho and westernmost Wyoming.Glacicavicola bathyscioides has only been foundin lava tube caves near permanent ice, apparentlyfeeding on bacterial slimes, and dead and possiblylive arthropods. The caves from which it is knownrange in elevation from 1525 to 2891 meters. Thisspecies apparently requires the constantly cool andmoist conditions provided in the caves. Its eyelesscondition and pale coloration suggest it is confinedto, and has evolved in, cave or subterranean habi-tats. Dispersal capabilities of this species are un-known. Potential suitable habitat can be foundthroughout much of the basin assessment area.Much of this habitat, however, is effectively inac-cessible given the probably limited dispersal capa-bilities of the species. The remote nature of thesites from which this species is known providesconsiderable buffering from human habitat alter-ation. Direct destruction or breaching of the cavesis probably the greatest human-induced hazard,but this seems unlikely given the known localities.Perhaps the greatest overall threat is of regionalclimate change. LaBonte (1995) suggests that theremote and relatively inaccessible habitat, in com-bination with the greatest foreseeable threats origi-nating from relatively unmanageable sources,render providing this species with threatened andendangered protection questionable and recom-mends placing G. bathyscioides on a “watch” listand monitoring its status in known sites.

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Insecta, Lepidoptera—

Limenitis archippus lahontani Herlan(Nymphalidae). Although a federally listed candi-date species, this is not a rare or endemic subspe-cies (Hammond 1994). It lives in riparian habitatsalong rivers and streams in desert lowland areas,where the larvae feed on willows (Salix spp.) It iswidely distributed in southern Idaho, eastern Ore-gon, and eastern Washington.

Polites mardon Edwards (Hesperiidae). This spe-cies lives in wet meadow habitats, and the larvaefeed on grasses. It appears to be an ancient, relictspecies of the late Tertiary period that only sur-vives today in four widely disjunct populationcenters in the Pacific Northwest. It is a rare spe-cies because of natural, prehistoric decline duringthe Pleistocene, rather than because of humandisturbance (except in western Washington). Onepopulation center is located on the Tenino prairiesnear Olympia, Washington. These populations arepotentially threatened by human development andecological succession to exotic Scotch broom(Cytisus scoparius (L.) Link). The other threepopulation centers are high mountain meadowsalong the east slope of the Cascade Range nearMount Adams, high mountain meadows along thesummit of the Cascade Range in Jackson andKlamath Counties in Oregon, and mountain mead-ows of coastal Del Norte County, California.These three populations seem to be abundant andstable at present but could be threatened by landmanagement practices on federal lands. Hammond(1994) suggests that P. mardon is one of two but-terfly taxa in the basin assessment area qualifyingas candidates for federal listing as endangeredspecies.

Insecta, Orthoptera—

Acrolophitus pulchellus (Bruner) (Acrididae).Only two specimens are known of this species,both collected at Birch Creek, Idaho, in 1883,associated with the plant Grayia polygaloides(probably G. spinosa (Hook.) Moq.; the onlyGrayia found in the PLANTS database) (USDANRCS 1997). Both A. pulchellus and its closelyrelated species A. nevadensis (Thomas) (which is

a localized and rare species) are unusual becausethey occur significantly north and west from otherrelated species in this genus. Surveys in Nevadaand Idaho have not collected this species, thus it islikely A. pulchellus is rare or extinct (Otte 1996).

Bureau of Land Management sensitive spe-cies—In the basin assessment area, BLM regionaloffices list six sensitive invertebrate species (table3). The FS has not listed any terrestrial inverte-brates in their regional sensitive species lists.

Gastropoda—

Megomphix lutarius Baker (Megomphicidae).This species was probably originally rather welldistributed in the Blue Mountains, Oregon. Its cur-rent distribution is uncertain, as recent surveys atthe type locality and adjacent areas on the UmatillaNational Forest have not recovered this species.Its habitat is north-facing small basalt cliffs inDouglas-fir forest with bryophytes, ferns, andbushes. Past and continuing intense logging andgrazing throughout most of the Blue Mountainsthreaten this species. Frest and Johannes (1995)recommend federal and state listing as endangered;and sensitive species listing by the FS and BLM,because of endemism and extensive habitat modifi-cation of its known range.

Oreohelix strigosa delicata Pilsbry(Oreohelicidae). The original distribution of thissubspecies is only known with certainty from thetype locality. Its current distribution is uncertain;areas on the Umatilla and possibly Wallowa-Whitman National Forests should be surveyed.The type locality is in a moderately steep basaltcreek canyon in fairly open ponderosa pine andDouglas-fir forest with some deciduous under-story and common grasses. Grazing, logging, androad construction threaten the type locality. Muchof the Blue Mountains has been affected by log-ging, insect infestations, and fires, all of whichthreaten this subspecies throughout its range. Frestand Johannes (1995) recommend this subspeciesbe considered for listing on the federal and statesof Oregon and Washington lists as endangered,and as sensitive by FS and other federal and stateland and wildlife agencies.

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Insecta, Coleoptera—

Nebria gebleri fragariae Kavanaugh (Carabidae).This subspecies is only known from northeasternOregon near the Strawberry Mountains. It hasbeen collected from the banks of montane perenni-al streams at elevations ranging from 1500 to 2300meters. The streambanks generally consist ofunconsolidated cobble-gravel, sand, or mud andare probably at least ephemerally seasonally flood-ed. These banks range from level to steep andoften have only sparse vegetation cover. Adultsare fully winged, but flight has not been observed;potential flight range is unknown. If adults are notcapable of flight, active dispersal would be limitedto walking by adults and larvae, with the possibilityof passive dispersal via downstream drift. Al-though seemingly suitable habitat is prevalentthroughout the region, contiguous or nearby suit-able habitat may be necessary for successful dis-persal. Nontarget effects from insecticides is apotential threat to this subspecies. The tolerance ofthis subspecies to habitat perturbation and degra-dation by logging, stream pollution, and livestocktrampling is unknown. Much of the habitat is con-tained within the Strawberry Mountain Wilderness,which may provide adequate buffering from man-agement actions. LaBonte (1995) suggests thatalthough limited in its distribution, this subspeciesdoes not seem to be in danger of any imminentthreats, especially with so much of its knownrange contained within a wilderness area.

Nebria vandykei wyeast Kavanaugh (Carabidae).This subspecies is known only from the OregonCascade Range from Mount Hood south towardthe Three Sisters. It is restricted to alpine habitats,perhaps extending down into the highest subalpineareas (1350 to 3400 meters). Primary habitatconsists of alpine ice and snow fields. Alpine andupper subalpine rocky stream banks function asseasonal thermal refugia during summer and earlyautumn. This subspecies is a predator-gleaner,foraging at night on the ice, snow, soil, and rocksurfaces for dead, old-immobilized, or active in-vertebrates. Nebria vandykei wyeast is entirelyflightless. Direct contact from pesticide drift or

ingestion of pesticide-contaminated arthropods arepossible risks to this subspecies. Based on existingknowledge, LaBonte (1995) recommends at mostthis species be placed on a “watch” list.

Insecta, Lepidoptera—

Charidryas acastus dorothyea Bauer(Nymphalidae). According to Hammond (1994),this may not be a valid taxonomic entity. Becausethis subspecies is only found at low elevationsalong the Snake River, a hybrid suture zone, itmay be a hybrid between C. acastus acastus andC. acastus sterope.

Identified species of special concern—Expertshave identified additional unlisted species as rareor endemic in the basin assessment area (see ap-pendix 4). Although we do not necessarily advo-cate listing all these taxa on agency sensitive spe-cies lists, nonetheless rare or endemic invertebratesdo exist in the basin assessment area and somemay bear further watching. No one set of criteriawas used by all specialists to determine which spe-cies should be considered rare or endemic. Con-tract reports should be consulted to determine thecriteria used for each taxonomic group.

Frest and Johannes (1995) identified 95 terrestrialmollusks (87 land snails and 8 slugs) as specieswarranting additional conservation attention. Mol-lusk diversity is concentrated in specific, relativelysmall portions of the basin assessment area. Inparticular, some species are confined to calcareoussubstrates, which make up a small part of the totalbasin assessment area. Even in the outcrop areas,many species, particularly those of special con-cern, are limited to a small portion of the totaloutcrop area. Certain drainages and narrowlycircumscribed geographic areas are particularlysignificant to mollusk biodiversity (Frest and Jo-hannes 1995). Preeminent are portions of theColumbia Gorge, Hells Canyon, the lower SalmonRiver, the Clearwater, the Clark Fork, and theBitterroot drainages. In some instances, other sitesare also significant, such as a few localities withschist or limestone substrate in western and south-eastern Idaho and in western Montana. Similarly,

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springs in the Upper Klamath Lake drainage,the Columbia Gorge, southeastern Idaho, andspecific portions of the Oregon interior basins,western Wyoming, and the northern quarter ofthe basin assessment area are significant to variousmollusks.

The basin assessment area is inhabited by atleast three native earthworm species, belongingto three genera (James 1995). Driloleirusamericanus Smith was considered for inclusion inthe International Union for the Conservation ofNature (IUCN) Invertebrate Red Data Book(Wells and others 1983) because its habitat wasthreatened and its range was not known to belarge. The currently available information suggestsit may be a narrow endemic utilizing a threatenedhabitat (grassland sites with good soil). The collec-tion data give little detailed habitat information.The three sites (near Pullman and Ellensburg,Washington, and Moscow, Idaho, [Fender andMcKey-Fender 1990]) are located in what is nowagricultural land, grassland, and shrubland. Theother two native species, Drilochaera chenowith-ensis McKey-Fender and Argilophilus hammondiMcKey-Fender, may be somewhat tolerant ofhabitat conversion to agriculture. Learning moreabout their ranges and ecological flexibility wouldenable land managers to determine if special habi-tat protection measures are necessary.

Hammond (1994) cites Parnassius clodiusshepardi Eisner (Papilionidae) as the only butterflyspecies in the basin assessment area that is a po-tential new candidate for federal listing under theEndangered Species Act. This species has a re-stricted habitat threatened by land managementpractices along the Snake River. Four other butter-fly species, Pyrgus scriptura Boisduval(Hesperiidae), Ochlodes yuma Edwards(Hesperiidae), Colias gigantean Strecker(Pieridae), and Mitoura johnsoni Skinner(Lycaenidae) are rare within the basin assess-mentarea but are common in other parts of NorthAmerica.

Based on existing information, LaBonte (1995)determined two terrestrial predaceous beetle spe-cies, Scaphinotus mannii Wickham (Carabidae)

and Cicindela columbica Hatch (Cicindelidae),are potentially threatened or endangered. Scaphi-notus mannii has stringent habitat requirementsand is confined to riparian strips in the canyons oflowland tributaries of the Snake River. Probablethreats include flooding of habitat from damming,human encroachment, pesticides, and cattle graz-ing and trampling. Cicindela columbica is restrict-ed to sandbars and sand dunes in riparian zones oflarge lowland rivers. This is a highly sensitive spe-cies that may be threatened by damming, tram-pling of habitat accessible to humans and livestock,and intensive collecting by tiger beetle enthusiasts.LaBonte (1995) suggests that three additionalbeetles, Ctenicera barri Lane (Elateridae), Nebriavandykei wyeast, and N. gebleri fragariae arespecies that may warrant watching. Little is knownof C. barri, N.v. wyeast, and N.g. fragariae,which have apparently stable populations largelycontained within national forests and wildernessareas.

Lattin (1995b) identified five species of Hemiptera:Heteroptera of special concern within the basin as-sessment area. Micracanthia fennica (Reuter) andHebrus buenoi Drake and Harris are associatedwith hot springs, and Ambrysus mormon Montan-don is found chiefly in runoff from thermal waters.Chorosoma sp. nov. (Rhopalidae) is found onsand, adjacent to interior sand dunes. Boreostolusamericanus Wygodzinsky and Stys occurs alongthe riparian zone of streams and rivers; it is a relictspecies of great evolutionary and biogeographicalinterest.

Tepedino and Griswold (1995) cite 24 species ofbees endemic to the basin assessment area. Elevenof these taxa are extremely rare (some may beextinct), having been recorded at only a single site.Some have been recorded only once, many yearsago. Others seem to be specialists of uncommonor heavily utilized habitats such as sand dunes orlava beds. Although most (14 species) are, or arelikely to be, somewhat specialized foragers, noneis likely to be so important to its plant as to threat-en that plant’s existence if the bee is absent. An-other 168 bee species are listed that may be rare inthe basin assessment area.

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Crawford (McIver and others 1994) lists 147 spe-cies of arachnids believed to be largely or entirelyrestricted to rare or uncommon habitats, and assuch, could be adversely affected by land manage-ment practices. None of these species are currentlylisted, and too little is known of their status tomake listing practical at this time. These speciesare only examples, intended as an advisory thatsuch species and their habitats exist and needfurther study.

Unique Habitats for InvertebratesGiven the importance of habitat for conservationof invertebrates, habitats key to the conservationof the unique invertebrate fauna of the basin as-sessment area are listed below (See also specialhabitats sections in Frest and Johannes 1995,Lattin 1995b, McIver and others 1995, Tepedinoand Griswold 1995, for more specific examples).These habitats represent a partial list biasedtoward those taxa that have been studied enoughto merit concern about their habitats. It is sug-gested all floral or faunal surveys include concur-rent survey for invertebrates. The more taxacovered in a survey, the more likely importantassociations of habitat and ecological functionwill be illuminated. Further work will need to ad-dress all invertebrate functional groups and speciesof special concern.

Arid habitats—The invertebrates of arid habitatssuch as deserts and sand dunes need further atten-tion throughout the basin assessment area. Thesehabitats are known to contain many rare andendemic species of beetles, bees, and bugs, andother taxa as well. Increasing demands for recre-ational use by all-terrain vehicles are a threat tospecies restricted to dune habitats as are invasiveexotic grasses and weeds.

Riparian areas—Meadows and riparian areasare known to be rich in spiders, beetles, and otherarthropod predators as well as nonpredaceousbeetles, bees, butterflies, and mollusks. Some gen-eral occurrence information exists, but informationon a regional basis, studying invertebrates in differ-ent plant associations, is needed. The effects oflivestock trampling and other soil- and litter-dis-turbing activities should be included in any studies.

Calcareous substrates—Calcareous substratesprovide habitat for some species of mollusks. Inparticular, certain species are confined to suchunits as the Paleozoic Madison, Lodgepole, Mis-sion Canyon, Amsden, and Phosphoria: or theTriassic Martin Bridge.

Peatlands—Bogs and fens are known to havespecies of spiders and insects not recorded asoccurring in other habitats. One could assume theprey species and host plants of prey species alsomay be unique. Calcareous fens are rich in mol-lusks worldwide.

Geothermal areas—Geothermal areas are knownfor unusual assemblages of plants, invertebrateherbivores, and arthropod predators. The heatedsubstrate provides snow-free conditions and alonger growing season. Regionally unique bug andbeetle predators, relict outliers of otherwise south-erly species, are found in some of these areas.

Isolated gorges and narrow canyons—Shade,moisture, and cold air drainage all contribute toconditions reminiscent of cooler periglacial cli-mates. Unique spiders and other invertebrates(Coleoptera, Plecoptera, etc.) found in these areassuggest the possibility of a unique prey base andhost plants as well. The unusual algific talus slopesand maderate cliffs of the upper Midwest harbor aunique biota of some dozen disjunct or otherwiseextinct snails and over 50 disjunct plants (Frest1984, 1991). Such sites exist in the basin assess-ment area as well.

Alkaline lake shores—This habitat is compara-tively independent of the surrounding vegetation.The key factors for specialized invertebrates areproximity of water whose alkalinity is relativelyhigh, availability of stones, sand, and other naturalcover (for example, Saldidae: Ioscytus politus).

Caves—The key factors for specialized inverte-brates are total darkness, constant high humidity,relatively stable temperature, few predators,food-poor environment, and import ecosystemswith food webs based on organic matter fromoutside. Caves are also essential to theTownsend’s big-eared bats (Plecotus townsendiiCooper) and the Van Dyke (Plethedon vandykeii

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Van Denburgh) and Larch Mountain (Plethodonlarselli Burns) salamanders. Caves in the EasternUnited States and Texas are known to harbor anextensive endemic land snail and water snail fauna(Hershler and Holsinger 1990); little of the assess-ment area has been searched for suchtroglodytes or phreatic endemics.

Sand dunes—Sandy environments typically havehigh degrees of pollinator (bee) and grasshopperendemism. Also, these unique faunas face signifi-cant threats from recreational vehicle use. Off-road vehicle activity not only reduces floral re-sources necessary for reproduction but destroysnests and potential nest sites. Assemblages ofpollinator species differ markedly among dunes.

Managing to RetainInvertebrates and TheirEcological FunctionsTo retain the viability of invertebrate species overlandscapes, attention must be given to the effectsof management practices. Three tenets summarizedesirable effects of management practices: (1) var-ious forms of compositional and structural diversi-ty will help maintain biodiversity and ecosystemfunctions; (2) maintenance of litter layer and soilstructure and chemistry will sustain diversity andfunctions of the soil food web; and (3) preventingthe introduction of or eradicating exotic organismswill help maintain biodiversity and ecosystemfunctions. Although not the only factors affectinginvertebrate diversity and function, these three areof major importance to a broad range of taxa oc-curring in forested ecosystems.

Compositional and StructuralDiversityStructural diversity in this discussion includes theforest canopy, understory, coarse woody material,forest floor litter, and water features. Homologousto this in the range environment are the tree orlarge shrub layer, forbs and flowering plant layer,and the litter layer. The structure of the canopylayer resulting from harvest, stand-improvementactivities, or wildfire affects several functionalgroups. The remaining stand may be more or lesshospitable to various herbivores, thereby resulting

in different amounts of nutrients falling to the litteror different amounts of tree mortality. The chang-es may result in varying quality and quantity ofprey available to predators, both invertebrate andvertebrate. Changes in canopy density or composi-tion can affect habitat for predators, which maymitigate population irruptions of pest species. Also,these canopy changes result in microclimatic dif-ferences in the understory and coarse woody ma-terial-litter environment, which may be detrimentalfor some species. For example, if the light andmoisture regime is changed sufficiently, the under-story flowering plants may change, thereby result-ing in effects on pollinators, herbivores, andpredators. These physical changes may be inimicalto species such as land snails whose lack of mobili-ty may prevent them from seeking conditions in apatch of better habitat. Coarse woody materialmay dry out more quickly under open canopiesaffecting the internal environment within standingand down dead trees. Water features, such asrivers, streams, lakes, ponds, wetlands, and im-poundments, provide critical habitat for the greatdiversity of terrestrial arthropods restricted to theirmargins.

In the understory, management practices that dis-turb or disrupt the flowering plants and otherground vegetation, or compact or mix the soil mayprofoundly effect several functional groups oforganisms. Besides the direct impacts on organ-isms with limited dispersal capabilities or in a non-motile stage, habitats of many functional groupswill be disrupted. Plant and animal communitieswill change, sometimes with consequences detri-mental to certain species.

On the forest floor, the major structural elementsare coarse woody material, primarily down treeboles and large branches, and litter. This materialserves as habitat for vertebrate and invertebratepredators and their prey, and as a carbon sourcefor the soil food web. Various species of arthro-pods, nematodes, fungi, annelids, and bacteria areresponsible for the comminution and conversion ofthe wood to elements available to the soil. Suffi-cient coarse woody material is necessary, throughtime, to maintain soil productivity. Soil productivi-ty also relies on leaf litter, corpses, feces, andother sources of detritus.

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Soil Structure and ChemistryMaintenance of soil chemistry and structure willsustain soil health and fertility. This is vital to re-tain forest and range productivity and biodiversity.Chemical change owing to fire and structuralchange owing to compaction or mixing of soillayers are the two consequences of managementpractices that are of concern. Fire, whether naturalor planned, can consume the litter and coarsewoody material that is important structurally and isthe primary source of carbon and other elementsnecessary for the soil food web. Erosion resultingfrom loss of coarse woody debris or the materialsbinding the system further depletes the productivecapacity of the soil. Secondly, fire can volatilizenutrients found in the upper horizon of the soil aswell as change its water-retention characteristics.Structural changes caused by either compaction orsoil mixing can have long-lasting effects, changingsuccessional patterns and timing. These effects areexpected with management requiring multipleentries into a forested area.

Exotic OrganismsThe introduction or maintenance of exotic organ-isms can adversely affect range and forest succes-sion and also reduce invertebrate biodiversity.Sailer (1983) and Kim and McPheron (1993) re-ported that nearly 2,000 species of exotic insectsand mites have become established in NorthAmerica. Mattson and others (1994) listed all ofthe immigrant phytophagous insect species knownestablished in North America on native and intro-duced woody plants (trees and shrubs). More than368 species of exotic phytophagous insects havebecome established in North American (north ofMexico) forests, parks, woodlots, shelterbelts, andorchards. Of the known earthworms in the area,most are exotics (Fender 1985, Gates 1967). Cur-rently, there are at least 145 nonindigenous mol-lusk species (32 bivalves, 113 gastropods) in NorthAmerica north of Mexico (Turgeon and others1998). Lattin and others (1995) reported on effectof exotic crested wheatgrass on native insects inthe vast east-side region.

Without their native enemies to restrain populationgrowth, exotic organisms can prey on native spe-cies or occupy niches of native species, particular-ly if they are more competitive. They may neces-sitate pest eradication or suppression activities withconcomitant risks and expenses.

Invertebrate Research andMonitoring PrioritiesInvertebrate and microbial research and monitoringactivities have centered almost exclusively on themanagement of a handful of insect and fungal pestspecies. These types of studies are still necessaryas our forests and grasslands are managed for var-ious consumptive, aesthetic, wildlife, and othervalues. The practice of ecosystem managementand increased awareness of the many essentialroles of invertebrates, however, necessitatesbroadening the scope of invertebrate investiga-tions.

Development of sound management practices forinvertebrates begins with knowledge of the speciesor taxonomic groups found in an area, their specif-ic habitat requirements, geographic distributionsand ranges, and their ecological function. This in-formation is most valuable when it is integratedwith information from other taxa. The species,taxa, or functional groups chosen for researchcould be selected on the basis of presumed ecolog-ical importance or sensitivity to particular manage-ment activities.

Research EmphasisActive management to achieve and maintain cer-tain desired condition or commodity output objec-tives, necessitates the study of organisms thataffect or are affected by these objectives. As val-ues and circumstances change, the species ofimportance will change as well. For instance, theconversion of extensive mixed-conifer stands toseral ponderosa pine and western larch will cause achange in the complex of species that are impor-tant disturbance agents. Impacts caused by defolia-tors like the western spruce budworm andDouglas-fir tussock moth could decline, whereas

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pine regeneration pests such as the western pine-shoot borer (Eucosma sonomana) and the ponde-rosa pine tip moth (Rhyacionia zozana) likelywould become of more concern to managers.Likewise, the complex of bark beetle specieswould shift according to host tree availability.Changes in tree characteristics, such as bark thick-ness, have effects on subcortical faunal composi-tion. Land managers need tools such as standhazard rating schemes; predictive monitoring,analysis, and feedback; and nonpesticide controlmethods (for example, semiochemical and biologi-cal control agents) that are the result of appliedresearch. But the basic research for such productscannot be overlooked; without studies on basicbiology and taxonomy, dispersal behavior, naturalenemies, and other ecological topics, applied re-search would be reduced to progress achieved bytrial and error.

Besides their role as herbivores impacting timberand forage resources, invertebrates perform manyvital functions, most of which have not been quan-tified or even examined to any extent in the basinassessment area. Much of our information is fromrelated species in other areas that often have dif-ferent conditions, and as such, extrapolation isextremely limited. Because insects and other inver-tebrates constitute most of the faunal biomass,their function as a food source to many species ofbirds, reptiles, amphibians, and small mammalsdemands research attention. Invertebrates arefound at all trophic levels (except that of primaryproducer), and by virtue of their extraordinaryabundance, play a dominant role in most ecosys-tem processes. We also need to know more abouthow invertebrates respond to various changes inecosystems such as nutrient cycling, soil microbialbiomass, etc. Thus, an understanding of nonpestinvertebrate biology and ecology in the basin as-sessment area is essential to understanding man-agement effects and strategies.

Soil and litter organisms—Most basic informa-tion such as species or taxonomic groups foundin an area, their specific habitat requirements,geographic distributions and ranges, and their

ecological function is needed. Additionally, knowl-edge of the effects of management practices on thecoarse woody material, litter, and soils in relationto ecological function, or individual species viabili-ty is needed to extend knowledge from the westside to the vast Columbia River basin.

Arthropod predators—Basic information on spe-cies or taxonomic groups found in an area, theirspecific habitat requirements, and geographic dis-tributions and ranges are needed. Additionally,information on the effects of management practic-es on predation and predator-prey relations areneeded.

Arthropod pollinators—Basic information onspecies or taxonomic groups found in an area, theirspecific habitat requirements, breeding biology ofhost plants, and their geographic distributions andranges are needed. Sandy environments could begiven priority because of species endemism andbecause of threat from off-road vehicles. Assem-blages of pollinator species differ markedly amongdunes. This information will indicate which duneshave particularly high degrees of bee diversity andendemism. The next step would be to assess beecomposition and abundance under different man-agement practices.

Grassland herbivores—Studies examining theeffect of range management practices on plantsuccessional changes will help us to more fullyunderstand the impacts of these activities on theassociated herbivores. Grazing systems can pro-vide many permutations of rotation timing, intensi-ty, spatial and temporal extent, and length of de-ferment, which can differ from site to site. Theimplications of prescribed burning on plant andsubsequent herbivore diversity are unknown. Fac-tors such as fire interval, intensity, duration, sea-son, patchiness, and spatial extent need to beexamined to determine their effect on plant com-munity composition, as well as on invertebrateherbivore diversity and abundance.

Proposed introductions of exotic organisms tocontrol native pests require research to determinethe impact of the exotic on displacing other nativespecies that perform the same function as well asother nontarget hosts or prey.

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Extensive work has been done on the relation ofinsects and other invertebrates above and below-ground in such places as Konza, Kansas; PawneeNational Grassland, Colorado; and Tornada andSeveta, New Mexico. All are long-term ecologicalresearch sites.

Forest herbivores—The management of pest spe-cies continues to warrant research effort; there is aneed to monitor and manage species that threatenour ability to reach forest resource objectives. Pro-tecting individual or groups of trees from barkbeetle attack in campgrounds, historic sites, old-growth stands, and riparian buffers is an exampleof the need to protect against damage by specificpest species. The development of hazard ratingsystems are a priority for many species, includingregeneration pests and bark beetles.

Adequate silvicultural guidelines for the manage-ment of invertebrates in second-growth ponderosapine in the basin assessment area do not exist.

Lastly, studies on gaining a better understanding ofthe various ecosystem functions that forest herbi-vores perform are necessary. For instance, al-though it is known that herbivores are the preybase for many arthropod and vertebrate predators,little is known about the dietary preferences ofbats, birds, amphibians, and other predators oninvertebrate herbivores. Likewise, the contributionof invertebrate herbivores in creating wildlife habi-tat is relatively unexplored. One opportunity begin-ning to be examined is the manipulation of barkbeetles by using semiochemicals to produce snagsfor wildlife (Ross and Niwa 1997). This type ofresearch both expands our basic knowledge ofinvertebrate functions in forest ecosystems andlays the groundwork for further development ofpractical management tools.

Monitoring EmphasisInvertebrates can be used as sensitive measures offorest and grassland health, by using various taxa.The taxa to be used should be relatively easy tomonitor or should represent a range of functionalgroups (for example, millipedes, centipedes, col-lembola, orabitid mites, etc.). It is also desirable toselect taxa that are well understood taxonomically

and that have a good foundation of ecologicalresearch. For instance, butterflies are a group thatcan be monitored visually by nonentomologistswith relatively brief training (Hammond 1995a).Some species of harvester ants are excellent formonitoring as they have ties throughout manyparts of the food web. The soil food web has beensuggested as a prime indicator of ecosystemhealth. Measurement of disrupted soil processes,decreased bacterial or fungal activity, change in theratio of fungal to bacterial biomass, decreases inthe number of or diversity of protozoa, change innematode numbers, and nematode communitystructure or maturity index, can serve to indicateproblems long before the natural vegetation isobviously affected.

Indicator taxa may be useful for monitoring chang-es because of management activities in two funda-mentally different ways: (1) Their abundance orbiomass may be an index or surrogate for a criticalecosystem function. As such, they are significantat an inclusive resolution (whole group census),seldom on an individual taxon basis. For instance,the ratio of total bacterivorous nematodes to fungi-vorous nematodes may reveal critical dynamics ofhow the decomposer microbial food web functionsor is changed by management. (2) The richnessand diversity of invertebrates or selected functionalgroups may serve as an index of total ecosystemdiversity, which differs under various managementactivities. The abundance and distribution patternsof an uncommon species may indicate subtlechanges in limited microenvironments of interest.For these studies, taxa are significant at a specieslevel of resolution, and to be useful on a generalbasis must be readily sampled and amenable to thisdegree of taxonomic precision. For instance, totalant species richness may be a useful index of com-munity diversity, whereas the presenceof a specific ant species such as Amblyponeoregonense (Wheeler) may indicate undisturbedold-growth forest-floor conditions. Thus candi-dates for indicator status can include the mostabundant, widespread and species-rich assemblag-es, or the most habitat-constrained (and thus un-common) individual species or assemblages,depending on the monitoring objectives.

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A consideration in using invertebrates as bioindica-tors is practicality. Candidate taxa for monitoringshould, in general, be relatively well-known (interms of the taxonomy and functional role theyplay in a community) and functionally important;species-rich (enough species to avoid statisticalerrors inherent in small numbers, but not so rich asto overwhelm sampling protocols); amenable tocapture or observation with standardized low-technology techniques; common and widespread(see above for exceptions); and relatively easy toidentify (to an appropriate level of resolution—notnecessarily to species).

ConclusionsThe abundance and diversity of invertebrates pre-sent challenges to developing land managementstrategies. There are some general approaches,however, to managing the biodiversity of thesespecies groups that may be effective: (1) focus onkey functional groups, (2) preserve key habitats,(3) take care in management activities, (4) broadenthe scope of investigations, and (5) practice adap-tive management. Using these components ofmanagement likely will benefit biodiversity ofinvertebrates and retention of their manifold eco-system functions.

Focus on Key Functional GroupsBecause of the enormous biodiversity representedby invertebrates, with about 24,000 macroinverte-brate species in the basin assessment area, this re-port focused on broad functional groups of orga-nisms. Two functional groups have species partic-ularly susceptible to environmental perturbations:detritivores and nutrient cyclers, and predators.

Within the detritivory and nutrient cycling func-tional group, there are some organisms associatedwith litter, coarse woody debris, and soil whosepopulations could be in danger of extirpation. Re-tention of these components in sufficient amountmay preserve the functions these groups performin the ecosystem. Determining the amount suffi-cient is problematical. Research must determinethe effects of current and past management prac-tices on not only the abundance and diversity ofthese organisms but also on rates of decompositionand mineralization.

Among detritivorous species, essentially all terres-trial mollusk species were identified as species ofspecial concern. Portions of the Columbia Gorge,Hells Canyon, lower Salmon River, Clearwater,Clark Fork, and Bitterroot drainages are areasparticularly significant to mollusk biodiversity.Springs in the Upper Klamath Lake drainage, theColumbia Gorge, southeastern Idaho, and specificportions of the Oregon interior basins, and westernWyoming are also significant habitats for variousspecies (Frest and Johannes 1998; Hershler 1998,1999). These species can be assisted by identifyingand protecting these special areas. Three speciesof native earthworms inhabit the basin assessmentarea. Learning more about their ranges and ecolog-ical flexibility would enable land managers to de-termine if special habitat protection measures arenecessary.

Within the predator functional group, 13 species(8 beetles and 5 bugs) were given only as exam-ples of many for which additional information isneeded to determine if habitat protection meas-ures are necessary. There are other such species inthese and other functional groups, but time, space,and knowledge are inadequate to fully documenthere their scarcity or sensitivity to disturbance.Developing a consistent set of criteria for deter-mining species of concern also would be helpful.

Preserve Key HabitatsHabitat protection, rather than a species-by-species approach, may be appropriate for inverte-brates. Eight unique habitats key to the conserva-tion of invertebrate fauna of the basin assessmentarea are arid areas, riparian areas, calcareous sub-strates, peatlands, geothermal areas, isolated gorg-es and narrow canyons, alkaline lake shores, andcaves.

Take Care in ManagementThe viability of invertebrate species over land-scapes may be retained by giving attention to threemajor effects of management practices. Composi-tional and structural diversity will help maintainbiodiversity and ecosystem functions. Forest cano-py, understory, coarse woody material, and forestfloor litter; rangeland trees or large shrubs, forbs,and litter; canopy density and composition; light

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and moisture regime; and soil disturbance andcompaction all are important features. Mainte-nance of soil structure and chemistry will sustaindiversity and functions of the soil food web.

Preventing the introduction of or eradicating exoticorganisms will help maintain biodiversity and eco-system functions provided by native species.

Broaden the Scope of InvestigationsAlmost exclusively, invertebrate research andmonitoring have centered on the management of ahandful of insect and fungal pest species. The in-creased awareness of the multitude of essentialroles of invertebrates, however, warrants a broad-ening of the scope of invertebrate investigations toinclude soil and litter organisms, arthropod preda-tors, arthropod pollinators, grassland herbivores,and forest herbivores.

Experts have identified 132 species as examples ofrare or endemic taxa in the basin assessment area.Although we do not advocate listing these taxa onagency sensitive species lists, rare or endemicinvertebrates of the basin assessment area arediscussed, and some may bear further watching.

Invertebrates are unique and useful bioindicatorsof ecosystem change: various species can be usedas sensitive measures of forest and grasslandhealth. Surveys of invertebrates could be efficient-ly conducted at the same time as floral or faunalsurveys.

Practice Adaptive ManagementThe practice of adaptive management will advancebasic knowledge about invertebrates and the ef-fects management activities have on their survivaland function.

AcknowledgmentsMany people were involved in preparing this infor-mation on invertebrates. The report began withinformation on the invertebrates of the basin as-

sessment area inaccessible except to specialists orresearchers. Through the efforts of our contractorsand expert science panelists (appendix 1) informa-tion was assembled in a form from which thisreport could be prepared. Bill Emmingham, Di-anne Hildebrand, Sherm Karl, Steve Leonard, IralRagenovich, Kathy Sheehan, Keith Sprengel, andBeth Willhite offered helpful assistance in conduct-ing science panels. Kaz Thea provided informationon the status of the invertebrates under the Endan-gered Species Act.

Individual reports were written by RodCrawford—spiders; Terrence Frest and EdwardJohannes—mollusks; Paul Hammond—butterflies;Elaine Ingham—soil microbes; Sam James—earthworms; James Johnson—lacewings and para-sitoids; William Kemp—rangeland grasshoppers;Jim LaBonte—predaceous beetles; John Lattin—true bugs; Jim McIver—invertebrate predators;Andy Moldenke—soil and litter microarthropodsand invertebrate diversity; John Moser—mites;Darrell Ross—bole and branch herbivores; TimSchowalter—coarse woody debris chewers; VinceTepedino and Terry Griswold—bees; Mike Wag-ner and Joel McMillin—canopy herbivores. Chris-tine Niwa and Roger Sandquist pulled all thevarious reports together into one document andbridged the gaps. Jeff Miller also contributed toreports used.

We gratefully acknowledge the many suggestionsof Andy Moldenke and Jack Lattin. Sherm Karl,Bruce Marcot, Kurt Nelson, and John Lehmkuhlreviewed early drafts of this report. GaryDaterman, Kathy Sheehan, and Torolf Torgersenreviewed the final manuscript. Tom Quigleyserved as overall technical editor. Lynn Starr pro-vided assistance in incorporating the final com-ments of the many coauthors.

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55

Appendix 1The following persons participated in the panel discussions. An asterisk (*) indicates those individuals whoprepared contract reports.

Soil-nutrient cycling—Feb. 1-2, Portland

Elaine Ingham* Oregon State University Microbes

Sam James* Maharishi Intl. Univ. Annelids

Bill Fender Private consultant Annelids

Kermit Cromack Oregon State University Nutrient cycling

Andy Moldenke* Oregon State University Arthropods

Lloyd Elliott USDA-ARS Bacteria

Karen Bennett Deschutes NF, R6 Soil

Herbivores-range—Feb. 7-8, Portland

Bill Kemp* USDA-ARS Grasshoppers

Jim McIver* Blue Mountains Natural Ants, predatorsResource Institute

Tony Joern University of Nebraska Grasshoppers

Paul Hammond* Private consultant Butterflies

Larry Walker USDI-BLM Range management

Litter and coarse wood-detritivores—Feb. 9-10, Portland

Andy Moldenke* Oregon State University Litter arthropods

Tim Schowalter* Oregon State University Coarse wood chewers

John Moore University of Northern Colorado Coarse wood chewers

Terry Frest* Deixis consultants Mollusks

David Bridgwater Forest Insects and Diseases, R6 Insects and diseases

Robert McNeil Malheur NF, R6 Soil

Parasites and predators—Feb. 14-15, Portland

Ding Johnson* University of Idaho Lacewings, parasites

Torolf Torgersen USDA-FS-PNW Research Station Ants, parasites

Rod Crawford* University of Washington Spiders

Mike Ivie Montana State University Beetles

Nancy Campbell Timber, Cooperative Forestry Insects and diseases and Pest Management, R1

56

Herbivores-forest—Feb. 22-23, Corvallis

Paul Hammond* Private consultant Butterflies

Jeff Miller* Oregon State University Moths, parasites

John D. Lattin* Oregon State University Hemiptera

Mike Wagner* Northern Arizona University Canopy herbivores

Darrell Ross* Oregon State University Bark beetles

John Moser* USDA-FS-SRS Station Mites, bark beetles

Bruce Hostetler Forest Insects and Diseases, R6 Insects and disease

Pollinators—March 1-2, Corvallis

Vince Tepideno* USDA-ARS Pollinators

Terry Griswold* USDA-ARS Pollinators

Jean Findley USDI-BLM Range plants

Bob Meinke Oregon State University Rare plants

Bill Stephen Oregon State University Bees

Mike Burgett Oregon State University Honey bees

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Appendix 2Potential forest wildland management practicesby Dr. Bill Emmingham a

I. Site preparation

A. Prescribed burning

1. Pile and burn

a. Mechanical

b. Hand

2. Jackpot

3. Broadcast

B. Ripping

C. Scarification

D. Herbicides

II. Intermediate entries

A. Fertilization

1. N

2. K

B. Precommercial thinning

C. Pruning

D. Vegetation management

1. Herbicide

2. Mechanical

3. Livestock grazing

E. Commercial thinning

III. Regeneration methods

A. Even aged

1. Clearcut

2. Seed tree

3. Shelterwood

B. Uneven aged

1. Group

a Bill Emmingham, professor, Forest Science Department, Oregon State University, Corvallis, OR 97331.

58

2. Individual tree

C. Ground vs. cable

IV. Other

A. Grazing

B. Harvesting of special forest products (for example, fungi and firewood)

C. Pest management

1. B.t.

2. Virus

3. Semiochemicals

D. Exotics

1. Flora

2. Fauna

E. Fire control

1. Borate

2. Backfire

3. Exclusion

F. Amelioration of pest, fire, flood, wind, and volcanic disturbance

1. Grass seeding

2. Salvage logging

V. Natural disturbances

A. Drought

B. Wildfire

1. Groundfire

2. Stand replacement

C. Insect outbreaks and disease activity

1. Bark beetles

2. Defoliators

3. Root rot

4. Mistletoe

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Rangeby Drs. Sherm Karl and Steve Leonard b

I. Grazing

A. Grazing systems

1. Seasonal

2. Deferred

3. Rest rotation

B. Juniper and sagebrush control

1. Mechanical

2. Herbicide

3. Fire

a. Prescribed

b. Wildfire

II. Other

A. Harvesting of special products (for example, fungi and firewood)

B. Pest management

C. Exotics

1. Flora

a. Herbicidal control

b. Manual (grubbing)

c. Biological control (insects, rusts, etc.)

d. Grass seeding to prevent reinvasion after herbicide treatment.

2. Fauna

D. Fire control

1. Borate

2. Backfire

3. Exclusion

E. Amelioration of pest, fire, flood, wind, and volcanic disturbance

III. Natural disturbances

A. Drought

B. Wildfire

b Sherm Karl, range ecologist, Interior Columbia Basin Ecosystem Management Project, 112 East Poplar, Walla Walla, WA 99362.Steve Leonard, range ecologist, National Riparian Service Team, PO Box 550, Prineville, OR 97754.

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1. Groundfire

2. Stand replacement

C. Insect outbreaks and disease activity

Considerations

I. Temporal scale (How long would any effects last?)

A. Immediate less than 5 years

B. Short term (5 to 50 years)

C. Long term (more than 50 years)

II. Spatial scale (Over how large an area would any effects occur?)

A. Stand

B. Landscape

III. Forest cover (What cover types would be affected?)

A. LPP climax

B. PP climax

C. Dry mixed conifer—DF, GF, PP, WL

D. Moist mixed conifer—DF, WF, WL, WWP, LPP

E. High-elevation mixed conifer—ES, SAF, WBP, MH

F. Riparian/wetlands

PP = ponderosa pine, WL = western larch, DF = Douglas fir, GF = grand fir,WF = White fir, LPP = lodgepole pine, WWP = western white pine,ES = Engleman spruce, SAF = subalpine fir, WBP = whitebark pine,MH = mountain hemlock

IV. Range type (Which types would be affected?)

A. Juniper woodlands

B. Grasslands

1. Mountain

2. Palouse

C. Shrublands

1. Salt desert shrub

2. Xeric sagebrush

3. Mesic sagebrush

D. Riparian-wetlands

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V. Structural stage

A. Early

B. Stem exclusion

C. Reinitiation

VI. Season

VII. Intensity

A. Severity

B. Number of entries

VIII. What is the source of knowledge?

A. Experimental data from the basin assessment area

B. Extrapolated from outside the basin assessment area

C. No experimental data

62

Appendix 3Table 4—List of selected families of terrestrial arthropod predators found in the basin assessmentarea, with estimate of number of species, principal prey, and typical habitatsa

Family No. of Principal prey Habitat(common name) speciesb Immatures Adults Immatures Adults

Class Arachnida: 1,156-2,735Spiders, scorpions,pseudoscorpions,harvestman(53 families)

Order Araneida: 983-2,279 Immatures are As a group, As adults CommonlySpiders small replicas spiders prey encountered(32 families) of adults—prey on almost terrestrial

will have same every type anthropodfeatures but will of terrestrial predator. Foundbe smaller arthropod in every major

habitat, fromlitter to canopy,in all ecoregions

Agelenidae: 75-150 Medium to large- Logs, litter, soil(funnel-web sized hopping- surface, treespinners) running trunks, caves;

arthropods forest-rangeAmaurobiidae: 20-60 Medium to large- Forest floor, on

(white-eyed spiders) sized arthropods logs, trunks,under bark

Antrodaetidae: 8-20 Medium-sized Forest floor;(folding-door ground surface burrows intarantulas) arthropods range soil

Anyphaenidae: 10-20 Varied insects Trees, shrubs, (sac spiders) under rocks;

forest-rangeAraneidae: 30-60 Flying insects On shrubs, trees,

(orb-weavers) rocks; forest-range

Clubionidae: 30-100 Running On ground,(running spiders) arthropods vegetation;

forest-rangeDictynidae: 50-100 Flying insects, Ubiquitous;

(hackled-band hopping ground level toweavers) arthropods, shrubs, trees;

esp. Diptera, forest-range;Hymenoptera mainly on

vegetation (oftendead annualplants)

Gnaphosidae: 75-150 Medium to large- On ground, under (nocturnal hunting sized arthropods bark, tree trunks; spiders) forest-rangeHahniidae: 12-25 Small insects Varied, under (Hahniid spiders) objects on

ground, logs,litter, webs onmoist soil; forest;rare range species

63

Linyphiidae: 350-900 Small to Ubiquitous; (sheet-web medium-sized ground level to weavers) arthropods, shrubs, trees,

flying insects less common indry places;forest-range

Lycosidae: 60-120 Medium to large- Ground level; (wolf spiders) sized running forest-range

and hoppingarthropods

Oxyopidae: 2-5 Medium to large- On shrubs, trees;(lynx spiders) sized running forest-range

and hoppingarthropods,flying insects

Pholcidae: 5-15 Flying and Webs under rocks;(cellar spiders) hopping insects forest-range

Salticidae: 80-160 Mostly small Ubiquitous; on(jumping spiders) running, ground, shrubs,

hopping, flying trees; forest-insects range.

Tetragnathidae: 20-50 Weak-flying On shrubs, trees,(long-bodied insects, esp. in riparianorb-weavers) terrestrial and areas, forest-

aquatic rangeTheridiidae: 60-110 Flying, hopping Ubiquitous; grass (comb-foot weavers) insects, ants, and herbs, some

other spiders shrubs, trees,forest-range

Thomisidae: 75-150 Running- Ubiquitous; (crab spiders) hopping and ground level to

flying arthropods shrubs, trees, onflowers;forest-range

15 additional families 21-84 of AraneaeOrder Scorpionidae: 6-10 Immatures small Use substrate- Same as Common onScorpions replicas of adults, born signals adults ground in(1 family) with similar for prey habitats

feeding habits detection; feedon running orhoppinginsects

Vaejovidae 6-10 Crickets, On ground, innocturnal burrows, underinsects, rocks; dryarachnids rangelands;

one species indry to mesicforests

Order Phalangida (or 83-186 Immatures have Widespread as Same as Common on Opiliones): similar feeding group; small adults ground; primarily Harvestmen habitats as mouthparts— in forested areas(10 families) adults, but prey small prey

is smaller

Table 4—sList of selected families of terrestrial arthropod predators found in the basin assessmentarea, with estimate of number of species, principal prey, and typical habitatsa (continued)

Family No. of Principal prey Habitat(common name) speciesb Immatures Adults Immatures Adults

64

Ischyropsalididae 22-40 Small Under objects,decomposer litter, caves, oninvertebrates ground

Phalangiidae: 10-25 Small-medium Vegetation, ground(daddy-longlegs) sized level, under

invertebrates rocks, logs;forest-range

Nemastomatidae 22-40 Small Litter in forestdecomposerinvertebrates

Triaenonychidae 9-25 Small Logs, under woodinvertebrates on ground, litter;

forestSix additional families 20-56

of OpilionesOrder Solpugida: 10-25 Immatures small Running- Same as Ground level;

wind scorpions replicas of hopping adults rangelands(1 family)hopping adults arthropods

Eremobatidae 10-25 Ground-dwelling Under objects, onarthropods ground; dry

rangelandsOrder Chernetida 74-235 Immatures small Small insects Same as Litter, caves,

Pseudoscorpions replicas of adults moss, mammal(9 families) adults nests, under rocks

Cheliferidae 15-50 Small flies, Under rocks, litter,psocoptera, tree barkinsect larvae

Chernetidae 15-40 Small flies, Mammal nests,psocoptera, tree and log barkinsect larvae

Chthoniidae 15-40 Collembola, mites Litter, soil, rottenwood, moss,caves, tree bark,mammal nests

Neobisiidae: 15-40 Collembola Litter, moss5 other families of 14-65 Small flies andPseudoscorpions mites

Class Chilopoda 149-343 Immatures small Soil Generally Soil, litter, under centipedes replicas of invertebrates same as rocks, logs;

(12 families) adults adults forest-rangeOrder 50-100 Lithobiomorpha: (3 families)Lithobiidae 50-100 Small- to Litter, logs, under

medium-sized rocksarthropods

Order 70-145Geophilomorpha(3 families)

Chilenophilidae 30-60 Small soil Litter, soilinvertebrates

Geophilidae 15-30 Small soil Litter, soilinvertebrates

Himantariidae 15-30 Small soil Litter, soilinvertebrates

Table 4—List of selected families of terrestrial arthropod predators found in the basin assessmentarea, with estimate of number of species, principal prey, and typical habitatsa (continued)

Family No. of Principal prey Habitat(common name) speciesb Immatures Adults Immatures Adults

65

Schendylidae 10-25 Small soil Litter, soilinvertebrates

2 other orders and 7 29-98other families of

centipedesClass insecta 2,239-3,558(47 families)

Order Thysanoptera: 10-40 Immatures have Most are plant Same as adults On herbs, shrubs,Thrips similar feeding feeders, a few trees, typically(2 families) habits as adults, species prey near or within

with prey size on small flowersjust smaller arthropods

Aeolothripidae: 5-20 Other thrips, Flowers(broad-winged aphids, mites,thrips) other small

insectsThripidae: 5-20 Other thrips, Flowers, foliage of(common thrips) mites herbs, shrubs

Order Heteroptera: 184-550 Immatures small Plant feeders, Same as adults Ubiquitous; asideTrue bugs replicas of predators, from the beetles,(6 families) adults, with prey scavengers, is the most

size smaller parasites important groupof insectpredators

Anthocoridae: 10-20 Aphids, scales, On ground,(minute pirate bugs) other small forbs, shrubs,

arthropods treesLygaeidae: 10 Aphids, thrips, On ground, forb(seed bugs) larval layer; forest-

Lepidoptera range(most arephytophagous)

Miridae: 100-200 Aphids, larval On forbs, shrubs,(plant bugs) Lepidoptera, trees; forest-range

other smallarthropods(many more arephytophagous)

Nabidae: ~20 Variety of small On ground, forbs,(damsel bugs) arthropods shrubs; forest-

rangePentatomidae: ~15 A few are On forbs, shrubs,(stink bugs) predataors on trees; forest-

other insects range(most arephytocoris)

Reduviidae: 5-20 Wide variety of On ground, forbs,(assassin bugs) small arthropods shrubs, trees

Order Neuroptera: 17-60 Mostly Predaceous: Arboreal, Aerial: weak fliers(lacewings, owlflies) predaceous relatively weak arbuscular(3 families) prey

Chrysopidae: 5-20 Aphids, scales Aphids, scales Arboreal, Aerial(green lacewings) arbuscular

Table 4—List of selected families of terrestrial arthropod predators found in the basin assessmentarea, with estimate of number of species, principal prey, and typical habitatsa (continued)

Family No. of Principal prey Habitat(common name) speciesb Immatures Adults Immatures Adults

66

Hemerobiidae: 5-20 Aphids, scales Arboreal, Aerial(brown lacewings) arbuscular

Myrmeliontidae: 5-10 Ground-dwelling Ground Aerial(antlions) insects surface, dry

placesOrder Raphidoptera 2-10 Aphids Aphids Arboreal, Arboreal,

(1 family) arbuscular arbuscularRaphidiidae:

(snakeflies)Order Coleoptera 47 Invertebrates, all Small soft-bodied Epigean, litter Flowers and

(28 families) stages insects, (e.g., foliageaphids)

Cantharidae(soldier beetles)

Carabidae 420 Invertebrates, all Invertebrates, all Ubiquitous Ubiquitous,(Carabid beetles) stages. Some stages. Many (see adults). especially epigean.

mono- or mono- or Generally Prominent inoligophagous oligophagous endo- and alpine nival, burn,(e.g., mollusks), (e.g., collembola, epigean, endogean, forest,some omnivorous millipedes, litter, lacustrine, riparian,

mollusks), some subcortical and sand duneomnivorous habitats

Cicindelidae 18 Epigean Invertebrates, Generally in Epigean, generally(tiger beetles) invertebrates, larvae and adults open areas, in open areas,

larvae and adults some in some in forests.forests. Prominant inEndogean, lacustrine,with burrows riparian and sandopening onto dune habitatssoil surface

Cleridae 21 Xylophagous Xylophagous Subcortical or Flowers, foliage,(checkered beetles) insects in wood, insects, esp. within prey tree limbs and

galls, cones, esp. adult Scolytidae galleries and trunks,subcortical beetles tunnels subcortical(e.g., Buprestidae,Cerambycidae,Scolytidae).Some prey ongrasshopper eggs,bee and wasplarvae.

Coccinellidae 85 Same as adults Homoptera (e.g., Same as adults Ubiquitous when(ladybird beetles) aphids and prey present.

coccids) and On foliage,phytophagous flowers, treemites. Some limbs, andprey on eggs, trunksyoung instars orsmall larvae andpupae ofColeoptera,Diptera,Hymenoptera,

Table 4—List of selected families of terrestrial arthropod predators found in the basin assessmentarea, with estimate of number of species, principal prey, and typical habitatsa (continued)

Family No. of Principal prey Habitat(common name) speciesb Immatures Adults Immatures Adults

67

Lepidoptera,Thysanoptera

Colydiidae 7 Predators and Xylophagous Subcortical or Subcortical or(cylindrical bark beetles) parasites of beetles, esp. within prey within prey

xylophagous larvae (e.g., galleries and tunnelsbeetles, especially Buprestidae, tunnelslarvae (e.g., Cerambycidae,Buprestidae, Scolytidae)Cerambycidae,Scolytidae)

Cucujidae 9 Subcortical insects, Subcortical Subcortical Subcortical(flat bark beeltes) esp. larval and insects, esp.

adult beetles (e.g., larval and adultCerambycidae and beetles (e.g.,Scolytidae) Cerambycidae

and Scolytidae)Elateridae 140 Endogean, Herbivorous or Endogean, Foliage, flowers,(click beetles) subcortical, and nonfeeding. subcortical, tree limbs and

xylophagous decaying trunks, someinvertebrates. wood riparian underFacultatively stonesherbivorous

Histeridae 46 Invertebrates, all Invertebrates, all Carrion, feces, Carrion, feces,(hister beetles) stages, esp. larvae stages, esp. decomposing decomposing

of Coleoptera, larvae of plant material plant material,Diperta, Coleoptera, lacustrine/ lacustrine/Lepidoptera. Diptera, riparian and riparian andSeveral ant Lepidoptera. sandy areas, sandy areas,predators Several ant under bark, under bark,

predators ant nests ant nestsLampyridae 9 Earthworms, Many believed Epigean, litter, Vegetation, esp.(firefly beetles) mollusks, insect herbivorous or under rocks near riparian

larvae, millipedes nonfeeding in riparian areas. AlsoSome females areas subcortical“cannibalistic”on males of sameand other speciesof Lampyridae.Some femaleslarviform,feeding onmillipedes andmollusks.

Leptinidae 1 Ectoparasitic on Ectoparasitic on On beaver On beaver(mammal nest beetles): beaver (epidermis beaver

Platypsyllus castoris and epidermal (epidermis and Ritsema exudates). epiderman

exudates).Lycidae 8 Soft or fluid Small soft- Litter, Vegetation(lycid beetles) material in bodied insects? subcortical,

Table 4—List of selected families of terrestrial arthropod predators found in the basin assessmentarea, with estimate of number of species, principal prey, and typical habitatsa (continued)

Family No. of Principal prey Habitat(common name) speciesb Immatures Adults Immatures Adults

68

decaying wood decayingwood

Meloidae 41 Eggs of Orthoptera; Herbivorous Endogeous as Flowers, foliage,(blister beetles) eggs, larvae, and Orthopteran epigean

provisions of egg predators.solitary bees First instar

larvae ofsolitary bee broodpredators onflowers, in beenests thereafter

Melyridae 63 Small Small Subcortical, Flowers, foliage,(soft-winged flower beetles) invertebrates, all invertebrates, xylophagous litter

stages. Many are all stages. insectalso scavengers Many galleries,

herbivorous litter, vegetation,decaying wood,fungi. endo- andepigean, esp.sandy soils.

Ostomidae 14 Subcortical/ Subcortical/ Subcortical Subcortical;(bark-gnawing beetles) xylophagous xylophagous galleries of galleries of

invertebrates (esp. invertebrates xylophagous xylophagousColeoptera; e.g., (esp. Coleoptera, insects, stored insects; limbs,Scolytidae), e.g., Scolytidae), grains and trunks, and foliagestored grain and stored grain and cereal products of conifers; storedcereal product cereal product grains and cerealpests. Some are pests. Some are productsfungivorous. fungivorous.

Othniidae 1 Subcortical Subcortical and Subcortical Subcortical; limbs,(false tiger beetles) invertebrates, all xylophagous trunks, and

stages invertebrates, foliage ofall stages conifers

Pselaphidae 16 Mites, all stages; Mites, all stages; Endogean, Endogean,(short-winged mold beetles) eggs, larvae, and eggs, larvae, epigean, epigean, litter,

pupae of ants; and pupae of litter, litter, subcortical,small invertebrates; ants; small subcortical, ant nests,(e.g., collembolans, invertebrates; ant nests, mammal nestsfly larvae) (e.g., mammal nests

collembolans,fly larvae)

Pyrochroiidae 2 Facultative Herbivorous or Subcortical Subcortical,(fire beetles) predators of nonfeeding? foliage

subcorticalinvertebrates?

Rhipiphoridae 6 Ecto- and Pollen feeders Wasp and Flowers(rhipiphorid beetles) endoparasites of solitary bee

wasps, solitary nestsbees

Rhizophagidae 3 Subcortical/ Subcortical and Subcortical Subcortical(root-eating beetles): xylophagous xylophagousspecies of Rhizophagus insects (esp. insects (esp.

Coleoptera; e.g., Coleoptera; e.g.,

Table 4—List of selected families of terrestrial arthropod predators found in the basin assessmentarea, with estimate of number of species, principal prey, and typical habitatsa (continued)

Family No. of Principal prey Habitat(common name) speciesb Immatures Adults Immatures Adults

69

eggs and larvae eggs and larvaeof Scolytidae) of Scolytidae)

Salpingidae 7 Subcortical/ Invertebrates, Subcortical, Subcortical,(narrow-waisted bark beetles) xylophagous esp. galleries of litter, flowers,

invertebrates, esp. Scolytidae xylophagous and foliageScolytidae insects

Scydmaenidae 3 Mites, all stages; Mites, all stages; Litter, epi- Litter, epi- and(antlike stone beetles) other small other small and endogean,

invertebrates invertebrates endogean, subcorticalsubcortical

Silphidae 11 Larvae of Diptera, Larvae of Diptera- Carrion, Carrion, decaying(carrion beetles): possibly larvae Nicrophorus. decaying vegetation,species of and adults of Small vegetation, feces—Nicrophorus, coprophagous invertebrates— feces— Nicrophorus.Pteroloma Coleoptera (e.g., Pteroloma Nicrophorus. Litter, epigean—

Scarabaeidae)— Litter, Pteroloma Nicrophorus epigean—

Small Pterolomainvertebrates—Pteroloma.

Staphylinidae 300 Invertebrates, all Invertebrates, all Ubiquitous; Ubiquitous; epi-(rove beetles) stages stages epi- and endogean, litter,

Subcortical/ Subcortical/ endogean, lacustrine andxylophagous xylophagous litter, riparian areas,invertebrates invertebrates. lacustrine subcortical,Many mono- or Many mono- or and riparian decaying woodoligophagous; oligophagous; areas, and plant(e.g., preying on (e.g., preying on subcortical, material, fungi,fly larvae, all callembola, fly decaying wood bird andstages of ants, larvae, and plant mammal nests,parasites of fly millipedes, material, fungi, carrion, feces,pupae). Many mites, all stages bird and ant nests,presumably of ants). Many mammal nests, flowers, etc.detrivorous or presumably carrion, feces,fungivorous detrivorous or ant nests, etc.

fungivorousDerodontidaec 3 All stages of All stages of Trunks, Trunks, branches,(tooth-necked fungus beetles): Chermidae Chermidae branches, and twigs ofspecies of Laricobius (Homoptera); (Homoptera); and twigs of conifers

(e.g., Adelges (e.g., Adelges coniferspiceae piceaeRatzeburg) Ratzeburg)

Nitidulidaec 18 Cybocephalus on Saprophagous, Subcortical Subcortical,(sap beetles) Coccidae mycetophagous flowers, tree

(Homoptera); wounds, fungiEpuraea onscolytid eggs andlarvae;Glischrochilus,Nitidula,Pityophagus onScolytidae

Scarabaeidaec 5 Ant larvae Ant larvae Ant nests Ant nests; under(scarab beetles): stones in fields,

Table 4—List of selected families of terrestrial arthropod predators found in the basin assessmentarea, with estimate of number of species, principal prey, and typical habitatsa (continued)

Family No. of Principal prey Habitat(common name) speciesb Immatures Adults Immatures Adults

70

Table 4—List of selected families of terrestrial arthropod predators found in the basin assessmentarea, with estimate of number of species, principal prey, and typical habitatsa (continued)

Family No. of Principal prey Habitat(common name) speciesb Immatures Adults Immatures Adults

Cremastocheilus meadows, andpastures.

Tenebrionidaec 4 Larvae, pupae, and Larvae, pupae, Subcortical Subcortical(darkling beetles): teneral adults of and teneral

Corticeus Scolytidae adults ofScolytidae?

Order Diptera: 220-700 Larvae, adults eat Larvae,True flies different food adults(3 families) occur in

differenthabitats.

Asilidae: 50-200 Invertebrates Flying insects Down wood Aerial(robber flies)

Chamaemyiidae: 20-100 Aphids Arboreal, Aerial(aphid flies) arbuscular

Syrphidae:150-400 Aphids Pollen, nectar Arboreal, Aerial Aerial(hover flies) arbuscular

Order Hymenoptera: 500-900 Larvae are Social (ants, Larvae are As a group, theseBees, ants, wasps helpless, fed by vespids) or found insects are(4 families) adults solitary (mud- within nests widespread,

daubers, constructed common, andspider wasps) by adults ecologically

Formicidae: 150-200 Fed by workers Almost entirely Ubiquitous(ants) polyphagous

Pompilidae: 100-150 Fed by adult Spiders Ubiquitous(spider wasps) female

Sphecidae: 200-400 Fed by adult Medium to large Ubiquitous(mud daubers) female arthropods,

esp.Lepidoptera

Vespidae: 50-150 Fed by workers Medium to large Ubiquitous (paper wasps, arthropods, hornets) esp.

Lepidoptera

Totals: 3 classes, 16 orders, 112 families, between 3,544 and 6,636 species.

a Crawford 1995. Species number of noninsects derived from Crawford (1988), of beetles (Hatch (1953, 1957, 1961, 1965, 1971),and of other insects (Danks 1978) and the list of invertebrates of the H.J. Andrews Experimental Forest (Parsons and others1991), assuming similar percentages of species found in each taxon.

b Estimates of species number represent preliminary examination of literature or expert opinion.

c Family is predominantly nonpredaceous. Only the predaceous species are counted.

71

Appendix 4Table 5—Rare and endemic invertebrate speciesa

USDA Forest Service or USDIClass-order Genus and species Bureau of Land Management

speciesGastropoda Snails:

Allogona lombardii Lb

Allogona ptychophora solida LAnguispira nimapuna LCryptomastix n. sp. 1 LCryptomastix n. sp. 2 LCryptomastix populi LCryptomastix harfordiana LCryptomastix hendersoni LCryptomastix magnidentata LCryptomastix mullani blandi LCryptomastix mullani clappi LCryptomastix mullani latilabris LCryptomastix mullani tuckeri LCryptomastix n. sp.1 LCryptomastix n. sp. 2 LCryptomastix n. sp. 3 LCryptomastix n. sp. 4 LCryptomastix sanburni LDiscus brunsoni LDiscus marmorensis LMonadenia fidelis n. subsp. 1 LMonadenia n. sp. 1 LOgaridiscus subrupicola LOreohelix alpina LOreohelix amariradix LOreohelix carinifera LOreohelix elrodi LOreohelix hammeri LOreohelix haydeni hesperia LOreohelix haydeni perplexa LOreohelix idahoensis baileyi LOreohelix idahoensis idahoensis LOreohelix intersum LOreohelix junii LOreohelix strigosa delicata Cc

Oreohelix strigosa goniogyra LOreohelix strigosa n. subsp. 1 LOreohelix tenuistriata LOreohelix variabilis LOreohelix variabilis n. subsp. 1 LOreohelix vortex L

72

Oreohelix waltoni LPristiloma arcticum? crateris LPristiloma idahoense LPristiloma wascoense LVespericola columbiana depressa LVespericola n. sp. 1 LVespericola sierranus L

Slugs:Hemphillia camelus LHemphillia danielsi LHemphillia malonei LMagnipelta mycophaga LProphysaon humile LUdosarx lyrata lyrata LUdosarx lyrata russelli L

Arachnida- Spiders:Araneida Microhexura idahoana

Orchestina sp. 1 (undescribed)Zanomys kaibaZanomys aquiloniaMallos niveusDictyna piraticaEnoplognatha wyutaDipoena sp. 1 (undescribed)Chrysso pelyxChrysso nordicaTheridion sp. 1 (undescribed)Zygiella carpenteriFrontinella communisLepthyphantes rainieriScotinotylus sp. 6 (undescribed)Tachygyna exilisDiplocephalus subrostratusCeratinella sp. 3 (undescribed)Scotinotylus sp. 8 (undescribed)Disembolus torquatusWalckenaeria communisWubana utahanaDolomedes tritonArctosa littoralisZora hespera

Table 5—Rare and endemic invertebrate speciesa (continued)

USDA Forest Service or USDIClass-order Genus and species Bureau of Land Management

species

73

Clubiona mimulaScotinella sp. 2 (undescribed)Zelotes josephineZelotes exiguoidesZelotes tuobusCallilepis eremellaEbo ivieiXysticus gosiutusOzyptila conspurcataTmarus angulatusPseudidius sp. 1 (undescribed)Sitticus finschiiMarchena minutaMetaphidippus sp. 2 (undescribed)Neon ellamaeEuophrys monadnockHabronattus kubaiHabronattus jucundusHabronattus sansoniHabronattus sp. 3 (undescribed)Pellenes shoshoneusSynageles occidentalis

Arachnida- Harvestmen:Opiliones Speleonychia sengeri

Insecta- Cicindela columbicaColeoptera Ctenicera barri Wd

Scaphinotus mannii L

Insecta, Micracanthia fennica WHemiptera: Ambrysus mormon W

Heteroptera Boreostolus americanus WWygodzinsky:StysChorosoma n. sp. WHebrus buenoi W

Insecta, Andrena aculeataHymenoptera Andrena winnemuccana

Ashmeadiella sculleniHesperapis (Hesperapis) n. sp.Heterosarus (Pterosarus) n. sp.Hoplitis producta subgracilis

Table 5—Rare and endemic invertebrate speciesa (continued)

USDA Forest Service or USDIClass-order Genus and species Bureau of Land Management

species

74

Hylaeus lunicrateriusMacropis steironema opacaMegachile umatillensisCalliopsis barriOsmia ashmeadiiOsmia n. sp near laetaPerdita acceptaPerdita crassihirtaPerdita similes pascoensisPerdita barriPerdita salicis euxanthaPerdita salicis sublaetaPerdita wyomingensis sculleniPerdita wyomingensis wyomingensisHoplitis n. sp. near plagiostomaHoplitis orthognathusSynhalonia douglasianaSynhalonia frater lata

Insecta- Colias gigantean LLepidoptera Mitoura johnsoni

Ochlodes yuma LParnassius clodius shepardi LPyrgus scriptura L

Oligochaeta Driloleirus americanus LDrilochaera chenowithensisArgilophilus hammondi

a These species are currently not listed by any public entity as needing protection. It is the judgement of species or functional groupexperts that these species be considered for possible measures by federal or state agencies to protect these species. Gastropoda—Frest and Johannes 1995; Arachnida—McIver, LaBonte, and Crawford 1995; Coleoptera—LaBonte 1995; Hemiptera/Heteroptera—Lattin 1995b; Hymenoptera—Tepedino and Griswold 1995; Lepidoptera—Hammond 1994; Oligochaeta—James1995.

b L = recommended for listing. For reasons specified in the contract reports, these species are thought to need specific protection.

c C = currently listed.

d W = recommended to watch. These species are either rare or endemics. There is no information to indicate that specialmeasures are needed at this time to protect them or their habitats; however, because of reasons listed in the contract reports, it isprudent to validate their status occasionally. Species with no indicators (L, C, or W) are not known to need special protection.

Table 5—Rare and endemic invertebrate speciesa (continued)

USDA Forest Service or USDIClass-order Genus and species Bureau of Land Management

species

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