The response of small mammals to the invasion of coast wattle (Acacia longifolia var. sophorae) in a fragmented heathland, south-west Victoria

Ellen Mitchell and Barbara A. Wilson, School of Ecology and Environment, Deakin University, Geelong, Victoria 3217, Australia.


Abstract

This study aimed to assess the impact of the environmental weed, Acacia longifolia var. sophorae (Labill.) Benth. on small mammal communities in fragmented coastal heathlands. The study was undertaken near the Portland Aluminium Smelter in south-west Victoria, within an area considered to have high plant diversity and several rare and threatened fauna species. Fauna surveys for small mammals were conducted between 1979 and 2004 using a combination of cage and Elliott traps in grid and line formations. The results of the small mammal fauna surveys and several vegetation surveys conducted were analysed. Significant changes in vegetation composition were the loss of wet heathland areas, decline in native species and the increase in cover of environmental weeds, A. longifolia var. sophorae (coast wattle) and Leptospermum laevigatum (Sol. ex Gaertn.) F.Muell. (coast tea-tree). Vegetation analysis found a strong negative correlation between A. longifolia var. sophorae cover and plant species richness. A 50% loss in the floristic species present significantly altered the vegetation structure and composition. Vegetation communities have changed from short open heathlands to shrublands with a dense overstorey. This has had a significant effect on the small mammal populations as preferred habitat is no longer available and several threatened habitat specialists, including Pseudomys shortridgei, have disappeared.

 

Plant Protection Quarterly (2006) 21 (4) 148.