An assessment of the contributions of forest structure and spatial scale to faunal diversity patterns in the Adirondack mountain region.

摘要

Understanding patterns of biodiversity is of vital importance to conservation, particularly in forests where much of the species diversity worldwide resides. Relatively little is known, however, about what controls levels of diversity, particularly for invertebrate taxa. To address this issue, I studied the influence of structural habitat components and spatial scale on the abundance, diversity, and distribution of several faunal groups in Adirondack forests: the red-backed salamander (Plethodon cinereus), burying beetles (Nicrophorinae), ground beetles (Carabidae), and ground spiders. I examined four hypotheses: (1) increases in forest habitat components that favor reproduction or foraging would increase abundance or diversity, (2) greater habitat heterogeneity resulting from ice storm canopy damage would enhance local species richness, (3) community turnover would increase as forest structure becomes more dissimilar, and (4) species diversity would be allocated to finer spatial scales for increasingly diverse taxa. I sampled 46 sites throughout the Adirondacks and classified them according to floristic and structural attributes. I collected 221 red-backed salamanders, 2,543 carabid beetles (50 species), 8,083 ground spiders (107 species), and 11,241 burying beetles (10 species) from May–August, 1999 and 2000. Three species of burying beetles (N. defodiens, N. tomentosus, and N. pustulatus) were more abundant in forests containing large volumes of CWD. Red-backed salamanders showed positive association to sites containing large amounts of live tree basal area, decayed CWD, and large numbers of downed woody objects. Ground beetle and ground spider communities were better characterized by tree species composition than by particular habitat variables. Species diversity among these taxa was found at small spatial scales and community turnover was relatively low, suggesting stand-level management may be an appropriate scale for conservation strategies. Identification of dispersal mechanisms that maintain these widespread species assemblages may be of greater consequence than defining strict forest habitat relationships.