Document: JEN-3-46-23

Regulation of diversity: Maintenance of species richness in changing environments.

BROWN, J.H.*, S.K.MORGANERNEST, J.M.PARODY and J.P.HASKELL

University of New Mexico, Albuquerque, NM 87131 USA ¹

Abstract:
In order to assess how diversity changes over time at sites undergoing environmental change, we examined three long-term data sets on taxonomic richness and composition: 1.) 22 years of rodent censuses from a site in the Chihuahuan Desert of Arizona; 2.) 50 years of bird surveys from a three-county region of northern Michigan; and 3.) approximately 10,000 years of pollen records from two sites in Europe. In all three cases, richness remained remarkably constant despite large changes in composition. The results suggest that environmental change can lead to changes in species composition but that species diversity as an emergent property of ecosystems is often maintained within narrow limits. Necessary conditions for such regulation of diversity include maintenance of relatively constant levels of productivity and resource availability in an open system with opportunity for compensatory colonizations and extinctions. In addition to studying the effects of diversity on biogeochemical processes, it will often be useful to think of species richness as an emergent consequence of ecosystem processes.

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This abstract is being presented at: 10:30 AM in session:
AVIAN ECOLOGY