The relative importance of environment, human activity and space in explaining species richness of South African bird orders

Wilson, John W., van Rensburg, Berndt J., Ferguson, J. Willem H. and Keith, Mark (2008) The relative importance of environment, human activity and space in explaining species richness of South African bird orders. Journal of Biogeography, 35 2: 342-352. doi:10.1111/j.1365-2699.2007.01792.x

Author Wilson, John W.
van Rensburg, Berndt J.
Ferguson, J. Willem H.
Keith, Mark
Title The relative importance of environment, human activity and space in explaining species richness of South African bird orders
Journal name Journal of Biogeography   Check publisher's open access policy
ISSN 0305-0270
Publication date 2008-02
Year available 2007
Sub-type Article (original research)
DOI 10.1111/j.1365-2699.2007.01792.x
Open Access Status
Volume 35
Issue 2
Start page 342
End page 352
Total pages 11
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell Publishing
Language eng
Formatted abstract
Aim  To assess the relative importance of environmental (climate, habitat heterogeneity and topography), human (population density, economic prosperity and land transformation) and spatial (autocorrelation) influences, and the interactions between these predictor groups, on species richness patterns of various avifaunal orders.
Location  South Africa.
Methods  Generalized linear models were used to determine the amount of variation in species richness, for each order, attributable to each of the different predictor groups. To assess the relationships between species richness and the various predictor groups, a deviance statistic (a measure of goodness of fit for each model) and the percentage deviation explained for the best fitting model were calculated.
Results  Of the 12 avifaunal orders examined, spatially structured environmental deviance accounted for most of the variation in species richness in 11 orders (averaging 28%), and 50% or more in seven orders. However, orders comprising mostly water birds (Charadriiformes, Anseriformes, Ciconiformes) had a relatively large component of purely spatial deviance compared with spatially structured environmental deviance, and much of this spatial deviance was due to higher-order spatial effects such as patchiness, as opposed to linear gradients in species richness. Although human activity, in general, offered little explanatory power to species richness patterns, it was an important correlate of spatial variation in species of Charadriiformes and Anseriformes. The species richness of these water birds was positively related to the presence of artificial water bodies.
Main conclusions  Not all bird orders showed similar trends when assessing, simultaneously, the relative importance of environmental, human and spatial influences in affecting bird species richness patterns. Although spatially structured environmental deviance described most of the variation in bird species richness, the explanatory power of purely spatial deviance, mostly due to nonlinear geographical effects such as patchiness, became more apparent in orders representing water birds. This was especially true for Charadriiformes, where the strong anthropogenic relationship has negative implications for the successful conservation of this group.
Keyword Avifaunal orders
Environmental factors
Human activities
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ
Additional Notes Article first published online: 2 NOV 2007

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biological Sciences Publications
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