Biodiversity models predict that deforestation and forest fragmentation will be the primary factors causing species extinction in the foreseeable future. However, current extinction rates can not even be estimated to within an order of magnitude, because of uncertainty surrounding the extrapolation of plant and vertebrate rates to terrestrial arthropods. In addition, arthropod responses to fragmentation are invariably based on terrestrial ground surface data, ignoring the crucial contribution of canopy arthropods to overall forest biodiversity. A new initiative, the Hope River Forest Fragmentation Project, is addressing the responses of canopy arthropods to fragmentation in New Zealand. New Zealand has a diverse arthropod fauna and has been identified as one of the 25 most important biodiversity hotspots in the world. However, 88% of New Zealand's forests have already been destroyed and most of what remains is heavily fragmented. The Hope River Project is the largest scale fragmentation study ever conducted, encompassing 14 fragment sizes from 0.01ha to >50,000ha and edge gradients from 0m to 1024m. One hundred and fourteen canopy interception traps were operated continuously from November 2000 to February 2001, for a total of 8,000 trap-days sampling effort and 120,000 arthropods sampled. There were highly significant differences in the abundance and composition of canopy arthropods along fragment edge and area gradients. Preliminary estimates for canopy Coleoptera and Diptera indicate substantial species losses with decreasing fragment area. These data provide a first indication of the reliability of extrapolating ground-based biodiversity scenarios to canopy arthropods.
Keywords: forest fragmentation, canopy arthropods
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA