Document: SCO-3-93-2

Effects of canopy removal on local and regional patterns of distribution and abundance.

COLLINS, S.L.* ¹ and S.M.GLENN ²

National Science Foundation, Arlington, VA 22230 USA ¹
University of British Columbia, Vancouver, BC V6T 1Z4 Canada ²

Abstract:
The distribution of species among sites and abundance of species within sites results from the interaction between local and regional processes. We analyzed the effect of dominance (a local process) by core species on the local and regional distribution and abundance of species in tallgrass prairie. By removing little bluestem, a core species, in replicated 5 by 10 m areas, we demonstrated that core species depress abundance of satellite species at the local scale. At larger scales, grazing by ungulates also reduces abundance of core species. At the regional scale, species richness was higher in grazed compared to ungrazed prairie. The increase in satellite species observed at the local scale, however, was not reflected at the regional scale. Rather, the pattern of proportion of sites occupied by species in grazed vegetation was similar to patterns in ungrazed prairie. In addition, there were no differences in the relationship between number of sites occupied and average abundance of each species between grazed and ungrazed vegetation. These results suggest that local scale interactions affect local distribution and abundance, but these patterns disappear at regional scales.

Keywords: Core-satellite; grassland; grazing; distribution and abundance

This abstract is being presented at: 9:00 AM in session:
Oral Session #58: Landscape Ecology.