PARENT SESSION
Contributed Oral Session 129: Biodiversity: Disturbance; Landscapes; Heterogeneity
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 513 E, Level 5, Palais des congrès de Montréal

Landscape geometry determines community response to disturbance.

Starzomski, Brian^*,1, Srivastava, Diane¹, ¹ The University of British Columbia, Vancouver

ABSTRACT- The impacts of disturbance and region size and its correlate, regional species richness, on non-equilibrium local species richness are subjects of great ecological interest. We experimentally manipulated the size and connectivity of patches of moss, and thus the microarthropod community that inhabits it, to test the interaction of disturbance frequency and region size on local species richness. This allowed us to see which of region size or disturbance was more important in structuring local species richness. Our results indicate that the region size is important as a supplier of re-colonists following disturbance. However, local richness and local abundance actually increased in highly fragmented regions, a fact we attribute to changed abiotic factors such as drying due to edge effect. Results suggest large regions and low disturbance rates do not cause higher local richness and abundance across all region size and disturbance combinations- rather, within region-size treatments, local diversity declines linearly with disturbance rate. We conclude that dispersal is important in maintaining local species richness and abundance, though this effect can be overridden in the short-term by abiotic effects such as edge effect. As well, region size is positively and linearly correlated with local species richness and abundance. We caution against attempting explanations for local species richness without considering regional effects such as dispersal, local effects like competition and facilitation, and abiotic effects such as edge effects.

Key words: Microarthropods, Disturbance, Region size, Dispersal