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Species richness, environmental correlates, and spatial scale: a test using South African birds

van Rensburg, B.J., Chown, S.L. and Gaston, K.J. (2002) Species richness, environmental correlates, and spatial scale: a test using South African birds. The American Naturalist, 159 (5). pp. 566-577. ISSN 0003-0147


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Energy and habitat heterogeneity are important correlates of spatial variation in species richness, though few investigations have sought to determine simultaneously their relative influences. Here we use the South African avifauna to examine the extent to which species richness is related to these variables and how these relationships depend on spatial grain. Taking spatial autocorrelation and area effects into account, we find that primary productivity, precipitation, absolute minimum temperature, and, at coarser resolutions, habitat heterogeneity account for most of the variation in species richness. Species richness and productivity are positively related, whereas the relationship between potential evapotranspiration (PET) and richness is unimodal.

This is largely because of the constraining effects of low rainfall on productivity in high-PET areas. The increase in the importance of vegetation heterogeneity as an explanatory variable is caused largely by an increase in the range of vegetation heterogeneity included at coarse resolutions and is probably also a result of the positive effects of environmental heterogeneity on species richness. Our findings indicate that species richness is correlated with, and hence likely a function of, several variables, that spatial resolution and extent must be taken into account during investigations of these relationships, and that surrogate measures for productivity should be interpreted cautiously.

Item Type: Article
Copyright, Publisher and Additional Information: © 2002 by The University of Chicago. Reproduced in accordance with the publisher's self-archiving policy.
Keywords: energy availability, habitat heterogeneity, primary productivity, potential evapotranspiration, grain
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Biological Sciences (Sheffield) > Department of Animal and Plant Sciences (Sheffield)
Depositing User: Repository Assistant
Date Deposited: 17 Jul 2006
Last Modified: 06 Jun 2014 17:09
Published Version: http://www.journals.uchicago.edu/AN/journal/conten...
Status: Published
Publisher: The University of Chicago Press
Refereed: Yes
URI: http://eprints.whiterose.ac.uk/id/eprint/1445

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