Arthropod Diversity and Conservation in Old-Growth Northwest Forests'
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AMER. ZOOL., 33:578-587 (1993) Arthropod Diversity and Conservation in Old-Growth mon et al., 1990; Hz Northwest Forests complex litter layer 1973; Lattin, 1990; JOHN D. LATTIN and other features Systematic Entomology Laboratory, Department of Entomology, Oregon State University, tural diversity of th Corvallis, Oregon 97331-2907 is reflected by the 14 found there (Lawtt SYNOPSIS. Old-growth forests of the Pacific Northwest extend along the 1990; Parsons et a. e coastal region from southern Alaska to northern California and are com- While these old posed largely of conifer rather than hardwood tree species. Many of these ity over time and trees achieve great age (500-1,000 yr). Natural succession that follows product of sever: forest stand destruction normally takes over 100 years to reach the young through successioi mature forest stage. This succession may continue on into old-growth for (Lattin, 1990). Fire centuries. The changing structural complexity of the forest over time, and diseases, are combined with the many different plant species that characterize succes- bances. The prolot sion, results in an array of arthropod habitats. It is estimated that 6,000 a continually char arthropod species may be found in such forests—over 3,400 different ments and habitat species are known from a single 6,400 ha site in Oregon. Our knowledge (Southwood, 1977 of these species is still rudimentary and much additional work is needed Lawton, 1983). throughout this vast region. Many of these species play critical roles in arthropods have lx the dynamics of forest ecosystems. They are important in nutrient cycling, old-growth site, tt as herbivores, as natural predators and parasites of other arthropod spe- mental Forest (HJ cies. This faunal diversity reflects the diversity of the environment and old-growth Dougi the arthropod complex provides a sensitive barometer of the conditions lamette National of the forest. Conservation efforts for forest arthropods are limited at Oregon. The HJA present and controlled largely by land-use policies. For example, an effort by the U.S. Fore is being made to include arthropods in conservation efforts for the North- consequences of ern Spotted Owl and arthropods will be included in the Forest Health ulation. It was a Monitoring program now underway by the U.S. Forest Service. Evidence western Coniferot: from other parts of the world suggest that arthropods that depend upon International Bio large pieces of dead wood may be particularly threatened by forest man- 1960s, was nun( agement practices. Much remains to be done in the conservation of forest logical Reserve ii arthropods. one of the first Na INTRODUCTION carpus Blume, Populus L., Quercus L., and funded, Long-Tc Sites in 1980. Toe The old-growth forests of the Pacific Salix L.) (Franklin and Dyrness, 1971). The large trees develop extensive canopies char- on the site and c( Northwest form a distinctive biotic region tigations relate( that extends along the Pacific Coast from acterized more by their height than breadth. These conifer species achieve great age. Included in these southeast Alaska to northern California. many involving Waring and Franklin (1979) characterized Many of the oldest individuals of each spe- cies are found in these forests (e.g., Sitka lated informatior these forests as unique in their size and in paper. the longevity of the individuals of the dom- spruce [Picea sitchensis (Bong.) Carr.] >500 inant tree species, resulting in very large yr, Douglas-fir [Pseudotsuga menziesii ARTHROPODS 0 accumulations of biomass. The 25 domi- (Mirb.) Franco] >750 yr, Alaska yellow- cedar [Chamaecyparis nootkatensis (D. Don) Insects were fi nant tree species are conifers rather than Northwest betwt hardwoods although there are hardwood Spach] > 1,000 yr, western red cedar [Thuja plicata Donn ex D. Don] > 1,000 yr, coast John Kirk Town taxa found in the forests (e.g., Acer L., Alnus Philadelphia (H Mill., Castanopsis (D. Don) Spach, Litho- redwood [Sequoia sempervirens (D. Don) Endl.] >1,250 yr) (Waring and Franklin, he collected spt 1979). Other related attributes of the forests growth forest i From the Symposium The Crisis in Invertebrate are the presence of massive amounts of dejeani, describe Conservation presented at the Annual Meeting of the coarse woody debris (CWD) as snags or on ist, Louis Reich( American Society of Zoologists and the Canadian Soci- less, nocturnal ti ety of Zoologists. 27-30 December 1992, at Vancou- the ground (Maser and Trappe, 1984; Har- ver, British Columbia. mon et al., 1986; Maser et al., 1988; Har- of Omus, collect 578 V le OLD-GROWTH FOREST ARTHROPOD CONSERVATION 579 mon et al., 1990; Harmon, 1992) and a deep, also was described by Reiche. These were complex litter layer (Franklin and Dyrness, the first insects to be recorded in the sci- 1973; Lattin, 1990; Moldenke, 1990). These entific literature from the Pacific Northwest and other features contribute to the struc- (Hatch, 1949). mversity, tural diversity of the forests—diversity that Other collectors came to the region in the is reflected by the diversity of arthropods years that followed. M. H. Hatch (1949) found there (Lawton, 1983; Asquith et al., provided an interesting account of the his- long the 1990; Parsons et al., 1991). tory of entomology in the Pacific Northwest. re corn- While these old forests have great stabil- One collector/sportsman was Lord Wal- of these ity over time and space, the forests are the singham from England who traveled through ollows product of several centuries of change Oregon and California in 1871 and 1872 young through succession following disturbance collecting moths while on a hunting expe- h for (Lattin, 1990). Fire and wind, besides insects dition. This trip resulted in a slim volume time, and diseases, are the main natural distur- on the plume moths of California and Ore- !succes- bances. The prolonged succession results in gon, complete with colored plates of most t 6,000 a continually changing mosaic of environ- species (Walsingham, 1880). At the time, ifferent ments and habitats available to arthropods European specialists wrote most of the sci- owledge (Southwood, 1977; Southwood et al., 1979; entific literature based upon these early col- r -eded Lawton, 1983). Over 3,400 species of lections. As the area became populated and is in arthropods have been documented from one institutions established, there was a gradual ling, old-growth site, the H. J. Andrews Experi- accumulation of knowledge on the arthro- spe- mental Forest (HJA). This site is a 6,400 ha pods of the region. The number of species tent and old-growth Douglas-fir forest in the Wil- involved, and the relatively few scientists nditions lamette National Forest east of Eugene, present, made progress slow. Even today, mited at Oregon. The HJA was established in 1948 the problem of numbers of species and the an effort by the U.S. Forest Service to examine the shortage of specialists continues. There are e North- consequences of long-term habitat manip- still many taxa largely unstudied and ,t Health ulation. It was a major component of the unknown (Stanton and Lattin, 1989).By way Evidence western Coniferous Forest Biome during the of example, the collection of the Systematic .nd upon International Biological Programme in the Entomology Laboratory, Department of •est man- 1960s, was named an Experimental Eco- Entomology, Oregon State University, was of forest logical Reserve in the 1970s, and became initiated over 100 years ago. Today, the col- one of the first National Science Foundation lection contains over 2,500,000 specimens Quercus L., and funded, Long-Term Ecological Research with heavy emphasis on the Pacific North- rrcss, 1971). The Sites in 1980. Today, over 50 scientists work west. It contains thousands of unstudied inopies char- on the site and conduct a variety of inves- specimens because there are no specialists than breadth. tigations related to forest ecosystems. for many groups. :eve great age. Included in these and past investigations are Our knowledge of insects in forest eco- luals of each spe- many involving arthropods. This accumu- systems grew in several ways. As interest in 3rests (e.g., Sitka lated information provides the basis for this these productive forests increased, there was ong.) Carr.] > 500 paper. increased interest in the arthropods of the ,tsuga menziesii forests, chiefly insects. Emphasis was on ARTHROPODS OF OLD-GROWTH FORESTS Alaska yellow- those species that were considered pests for tkatensis (D. Don) Insects were first collected in the Pacific one reason or another. Eventually this red cedar [Thuja Northwest between 1834 and 1836 by Dr. knowledge was synthesized by Keen (1952) > 1,000 yr, coast John Kirk Townsend, an ornithologist from and, more recently, by Furniss and Carolin rvirens (D. Don) Philadelphia (Hatch, 1949). Remarkably, (1977). The latter volume contains a vast ng and Franklin, he collected specimens of a typical old- amount of information on western forest mtes of the forests growth forest insect, the beetle, Omus insects, including many that occur beyond ;sive amounts of dejeani, described by the French coleopter- the region considered here. Central to the "D) as snags or on ist, Louis Reiche, in 1838. This is a flight- acquisition of such information were the rappe, 1984; Har- less, nocturnal tiger beetle. A second species Canadian and United States government- et a!., 1988; Har- of Omus, collected during the same period based forest services. Other major sources JOHN D. LATTIN of information were the many taxonomic work expanded, many additional specimens ■ A substantial nn revisions of major taxa found in forests (e.g., were added (Lewis and Maser, 1981; Ander- ciated with the wood boring beetles, sawflies, loopers, and son et al., 1982; Lightfoot, 1986). Emphasis debris (Schow spiders). These studies provided the back- was placed on aquatic taxa, the insects asso- (1984), Warre drop to studies focussing upon arthropods ciated with different plant species, and Peterken (1992 found in old-growth forests in western North extensive collections from the litter and soil ments of this fa America.