Small-scale patterns of species richness and floristic composition in relation to microsite variation in herb-rich woodlands
J. N. Price A B C and J. W. Morgan AA Department of Botany, La Trobe University, Bundoora, Vic. 3086, Australia.
B Current address: Institute of Ecology and Earth Sciences, University of Tartu, Tartu 51005, Estonia.
C Corresponding author. Email: Jodi.Price@ut.ee
Australian Journal of Botany 58(4) 271-279 https://doi.org/10.1071/BT09191
Submitted: 29 October 2009 Accepted: 10 May 2010 Published: 22 June 2010
Abstract
Non-riverine Eucalyptus camaldulensis (red gum) woodlands with herbaceous understoreys in southern Australia have been recognised as botanically significant due to their high small-scale species richness, but little is known about the factors that underpin these patterns. To examine the influence of local environmental variation (microsites) on small-scale vegetation patterns, we sampled vegetation under trees, away from trees, and in depressions and hummocks in three herb-rich woodlands. Trees influenced both the composition and richness of the ground-layer vegetation, with reductions in species richness found under trees in sites where incident light availability was reduced by >40%. Species composition and richness differed between microsites, indicating that spatial heterogeneity is an important factor affecting species distribution patterns. Patchiness in relation to abiotic factors creates environmentally and compositionally distinct patterns. Indicator species analysis found that all microsites could be distinguished by character species with some evidence for microsite limitation for only a few species, lending weak support for a niche-based model of community assembly for herb-rich woodlands. A more plausible explanation for extremely high small-scale species richness is the lack of dominant species in these low productivity woodlands.
Acknowledgements
We thank Ian Lunt for stimulating this research and his ongoing ecological discussions and encouragement. We thank Bob Parsons and three anonymous reviewers for helpful comments on an earlier version of this manuscript. David and Judith Thompson, Seraphina Cutler, James Shannon, Nicola Hardy and Poly McMillan helped with field data collection. Joe Edwards provided advice on soil analysis. JNP was funded by a La Trobe University Post-Graduate Award.
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