Forest macro-arthropods as potential indicators of ecosystem conditions in western Idaho: an analysis of community composition, biological diversity, and community structure

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The purpose of this study was threefold: to 1) inventory the macroarthropod community and important environmental variables in the Bear Creek and Indian Creek study area within the Payette National Forest (PNF) in western Idaho; 2) compare measures of community composition, diversity, and structure in forest macro-arthropod communities between patches of different sizes and treatment; and 3) assist PNF managers in their ecosystem management efforts by providing principles to guide the use of macro-arthropods as indicators of changing forest conditions. Transects with pitfall traps were used to collect macro-arthropods at 22 sites in the Bear Creek and Indian Creek study area during summer 1994. Five forest patch types in Abies grandis habitat types were sampled. At each transect, soil samples were collected and six environmental descriptor variables were analyzed according to patch treatment and patch size. Arthropod community composition, diversity, and structure were described according to relative abundance, and four measures of diversity. A total of 5455 macro-arthropod individuals, representing 17 orders and/or super-families and 219 species were collected in the study area. Macro-arthropod community composition, diversity, and structure did vary, usually significantly, by patch treatment and size. Useful measures of generic diversity include richness estimators α, β, and JK1. Examination of taxonomic diversity was also useful, especially for the more mobile arthropods. Pitfall traps provided copious data on the structure of the community in regards to predators and herbivores. Pitfalls, however, did not provide much information about the status of fungivores and parasites in the various different patches. Another trapping method such as the berlaise funnel, would likely provide more information about those functional groups which are likely operating at a finer scale of resolution than that tested by the pitfall trap. Employing both methods would provide a much better assessment of the community of arthropods living on the forest floor. The indicator species analysis program also provided very useful lists of species which are affiliated with particular patch conditions. Taken together, these measures could be adopted for use by forest managers to allow them to assess and monitor the effects of a management regime on the structure and composition of macro-arthropod communities as part of a comprehensive adaptive management plan.

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ELECTRONIC FILE - Zoology: Invertebrates