Monitoring and modeling terrestrial arthropod diversity on the Kenai National Wildlife Refuge
Matthew L. Bowser
John M. Morton
Rocky Mountain Research Station
In: McWilliams, Will; Moisen, Gretchen; Czaplewski, Ray, comps. Forest Inventory and Analysis (FIA) Symposium 2008; October 21-23, 2008; Park City, UT. Proc. RMRS-P-56CD. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 23 p.
The primary purpose of the Kenai National Wildlife Refuge (KENWR) is to "conserve fish and wildlife populations in their natural diversity," where "fish and wildlife" explicitly includes arthropods. To this end, we developed a Long Term Ecological Monitoring Program (LTEMP), a collaborative effort with the USDA Forest Inventory and Analysis (FIA) Program. In 2004 and 2006, we sweep-netted terrestrial arthropods on 255 100m2 circular plots systematically distributed at 5-km intervals over the 805,000 ha KENWR. These samples yielded 15,136 specimens, which were sorted to families and to species when possible. The comprehensive spatial coverage of the LTEMP sampling design provided spatial data suitable for species distribution modeling, but we sought to improve upon this design by explicitly accounting for imperfect detection. We proposed a rotating panel design where each site would be visited once every ten years. Imperfect detection would be accounted for by spatial sub-sampling within plots. Using Monte-Carlo simulation, we assessed the proposed design of LTEMP for accurately monitoring changes in arthropod species distributions over time. Our simulations demonstrated that, for species that are likely to be collected in a single 50m2 sweep net sample where they are present, the proposed LTEMP sampling design should provide accurate estimates of species distributions and local rates of colonization and extinction over the long-term. In order to document the landscape-scale patterns of arthropod diversity over the KENWR, we modeled arthropod family richness using random forest regression. Arthropod family richness data were obtained from LTEMP and topographic, temporal, and productivity variables were obtained from GIS datasets. The resulting map explained 22% of variation of diversity of sweep net samples. Highest diversity was predicted on the margins of coastal wetlands and in productive hardwood and mixed forests; lowest diversity was predicted at barren alpine sites.
Bowser, Matthew L.; Morton, John M. 2009. Monitoring and modeling terrestrial arthropod diversity on the Kenai National Wildlife Refuge. In: McWilliams, Will; Moisen, Gretchen; Czaplewski, Ray, comps. Forest Inventory and Analysis (FIA) Symposium 2008; October 21-23, 2008; Park City, UT. Proc. RMRS-P-56CD. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 23 p.