This new paper seems to speak to some of the issues raised in recent
emails..
Robin Hide
Camilleri, S., J. R. Thomson and R. M. Nally (2010). “The interaction
between land use and catchment physiognomy: understanding avifaunal
patterns of the Murray–Darling Basin, Australia.” Journal of
Biogeography 37(2): 293 - 304.
Keywords: Australia • biodiversity • bird atlas • birds •
catchment • multivariate correlations • watershed
Abstract:
Aim We assessed whether different patterns of land use within similar
physiognomic catchments (= watersheds) produced discernible effects on
avian assemblages and, if so, whether such effects were related to
particular land-use activities (e.g. extensive cropping).
Location Murray-Darling Basin in south-eastern Australia.
Methods We used a recently (2007) published physiognomic classification
of catchments based on different stream orders as our template. We used
a subset of data from the second Birds Australia atlas to calculate
reporting rates for each species in each subcatchment. We linked these
two sets of data with proportions of major land uses within catchments
to identify whether differences in proportions of land uses altered the
expected avifauna for catchments of the same nominal physiognomic class.
Results A significant proportion of the variation in bird reporting
rates was explained by the physiognomic classification. Additional
explanatory power resulted from including an interaction matrix of
land-use covariates. Livestock grazing was a major explanatory variable
in classes characterized by more mountainous catchments. Cropping
affected avifaunas consistently by producing a more uniform assemblage.
Main conclusions The physiognomic template was an important determinant
of avifaunal composition, but its interaction with land-use variation
within physiognomic classes doubled the amount of variance explained.
Within a physiognomic class, if one identifies the 'ideal' avifaunal
composition for that class one can identify land-use mixes that are
most likely to be beneficial for the avifaunas of that class and
recommend directions for large-scale management objectives vis-à-vis
mixtures of land-use types.
Copyright © 2010 Blackwell Publishing Ltd.
Correspondence to *Ralph Mac Nally, Australian Centre for Biodiversity,
School of Biological Sciences, Monash University, Melbourne, Vic. 3800,
Australia.
E-mail: m("sci.monash.edu.au","ralph.macnally");">
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