Differing responses to landscape change: implications for small mammal assemblages in forest fragments
Human modification of landscapes typically results in many species being confined to small, isolated and degraded habitat fragments. While fragment size and isolation underpin many studies of modified landscapes, vegetation characteristics are less frequently incorporated. The relative influence of biogeographic (e.g. size, isolation) and vegetation parameters on assemblages is poorly understood, but critical for conservation management. In this study, a multiple hypothesis testing framework was used to determine the relative importance of biogeographic and vegetation parameters in explaining the occurrence of an assemblage of small mammals in 48 forest fragments in an agricultural landscape in south-eastern Australia. Fragment size and vegetation characteristics were consistently important predictors of occurrence across species. In contrast, fragment isolation was important for just one native species. Differing abilities of species to move through the landscape provide a reasonable explanation for these results. We conclude that for effective conservation of assemblages, it is important to: (1) consider differing responses of species to landscape change, and (2) move beyond a focus primarily on spatial attributes (size, isolation) to recognise that landscape change also has profound effects on habitat composition and quality.
KeywordsAustralia Functional connectivity Habitat fragmentation Mammals Patch size Patch isolation Species richness Vegetation characteristics
We thank the many landholders that allowed us to work on their properties. We would also like to thank all those who assisted with field work. Trapping and handling of animals was conducted under Deakin University Animal Ethics Committee approval (A15/2001) and a Department of Sustainability and Environment Research Permit (10001802). Financial support was provided by the Holsworth Wildlife Research Endowment, Deakin University, and an Australian Postgraduate Award received by G. J. Holland. The comments of an anonymous reviewer improved an earlier version of the manuscript.
- Banks SC, Finlayson GR, Lawson SJ, Lindenmayer DB, Paetkau D, Ward SJ, Taylor AC (2005) The effects of habitat fragmentation due to forestry plantation establishment on the demography and genetic variation of a marsupial carnivore, Antechinus agilis. Biol Conserv 122:581–597. doi: 10.1016/j.biocon.2004.09.013 CrossRefGoogle Scholar
- Bennett AF (1987) Conservation of mammals within a fragmented forest environment: the contributions of insular biogeography and autecology. In: Saunders DA, Arnold GW, Burbidge AA, Hopkins AJM (eds) Nature conservation: the role of remnants of native vegetation. Surrey Beatty and Sons, Chipping Norton, pp 41–52Google Scholar
- Burnham KP, Anderson DR (2002) Model selection and multimodel inference: a practical information-theoretic approach. Springer, New YorkGoogle Scholar
- Dickman CR (1995) Agile antechinus. In: Strahan R (ed) The mammals of Australia. Reed Books, Chatswood, pp 100–101Google Scholar
- Donaldson A (2002) The value of linear roadside vegetation for maintaining native fauna in an agricultural landscape in south-western Victoria. Honours Dissertation, Deakin University, MelbourneGoogle Scholar
- Hanski I (1999) Metapopulation ecology. Oxford University Press, New YorkGoogle Scholar
- Land Conservation Council (1976) Corangamite study area. Land Conservation Council, MelbourneGoogle Scholar
- Lindenmayer DB, Peakall R (2000) The Tumut experiment—integrating demographic and genetic studies to unravel fragmentation effects: a case study of the native bush rat. In: Young AG, Clarke GM (eds) Genetics, demography, and the viability of fragmented populations. Cambridge University Press, Cambridge, pp 173–201Google Scholar
- McGarigal K, Cushman SA, Neel MC, Ene E (2002) FRAGSTATS: spatial pattern analysis program for categorical maps. University of Massachusetts, Amherst. Available at www.umas.edu/landeco/research/fragstats/fragstats.html
- Soulé ME (ed) (1987) Viable populations for conservation. Cambridge University Press, New YorkGoogle Scholar
- Walsh C, Mac Nally R (2004) The hier.part package, version 1.0-1. Supplementary package for the R statistical program. Available at http://cran.r-project.org/