|Revegetation: its biodiversity conservation effectiveness|
|Department of Environmental Biology
University of Adelaide
Widespread environmental degradation in the agricultural regions of Australia has resulted from 150 years of vegetation clearance, habitat fragmentation, introduction of exotic plants and animals and European farming practices. Revegetation has been widely hailed as a panacea, with the potential ability to address land, water and nature conservation goals simultaneously. The attainment of these goals, particularly the latter, however, has rarely been tested.
A study was conducted in the Tungkillo area of the Mount Lofty Ranges in South Australia, to assess the plant community structure and bird usage of agroforestry, revegetation, natural regeneration, remnant vegetation and roadside habitats. Comparisons could then be drawn between the planted habitats (agroforestry and revegetation) and the natural habitats (natural regeneration, remnant vegetation and roadside vegetation) to determine if the revegetation areas were meeting nature conservation goals effectively.
Overall, planted habitats were found to be far less diverse in native plants than the natural habitats. Rather than replacing or extending natural communities, they created new, artificial communities, with low diversity, high tree densities and low shrub and groundcover species richness.
Distinctly fewer birds and bird species were found in the agroforestry and revegetation areas than in the other three habitats, however, there was much variation between revegetation sites. Differences in bird usage were found to correlate with structural and floristic factors.
An assessment of the extent of revegetation and the characteristics of patches across the region showed that the majority of revegetation patches were small, distant from remnant vegetation and had relatively high proportions of edge habitat. In future, if revegetation programs are to assist in bird conservation, more effort needs to be made to link patches regionally, to facilitate colonisation of birds, and to establish appropriate vegetation communities at each site. Special attention needs to be focused on the requirements of animal species declining in abundance or distribution, as revegetation has largely failed to address their needs.
| Index |