PARENT SESSION
Organized Oral Session 49: Scaling species abundance, distribution and diversity: From pattern to process
Organizer(s): WE Kunin and H Lewis
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 511a, Level 5, Palais des congrès de Montréal
Scaling, heterogeneity, and the structure and diversity of communities.
Ritchie, Mark*,1, Olff, Han2, 1 Department of Biology, Syracuse, NY, USA2 Community and Conservation Ecology group, Haren, The Netherlands
ABSTRACT- Diversity measures and patterns are inherently scale-dependent, that is, one cannot specify a diversity measurement or pattern without also specifying its scale. Diversity also depends on heterogeneity, which itself may be scale-dependent.Many of the controversies over diversity patterns, and thus hypotheses about what controls diversity, arise because the patterns compare different-sized organisms sampled at different spatial scales over different spatial extents and patterns of heterogeneity. Using a model of species coexistence in fractal environments through differentiation in resource use and in the scale at which different species sample space, I show how resource partitioning, competition, and species interactions are dominant mechanisms generating diversity at small scales of observation (extent), while environmental capacity, colonization and local extinction processes are dominant mechanisms at large spatial extents. I test these predictions with field data from a variety of taxa. Further exploration of the model reveals that many well-known diversity patterns are predicted to change in their shape strictly as a consequence of increasing the spatial extent relative to the sampling scales of organisms. These shape changes occur because the pattern of heterogeneity also changes with extent. Guilds or communities of organisms that differ greatly in size and mobility (birds vs. plants) can therefore exhibit different diversity patterns when examined at the same spatial extent.
Key words: biodiversity, scaling, heterogeneity, fractal