When native vegetation is cleared for agriculture, habitats which were once continuous become divided into separate fragments. After intensive clearing, the separate fragments tend to be very small islands isolated from each other by crop land and pasture. In some regions of Australia, such as the wheatbelt of central western New South Wales, 90% of the native vegetation has been cleared, resulting in extreme habitat fragmentation.
Small fragments of habitat can only support small populations of fauna and small populations of fauna are more vulnerable to extinction. Fragments of habitat that are separated from each other are unlikely to be recolonised.
Furthermore, small fragments of habitat do not contain interior habitat. Habitat along the edge of a fragment has a different climate and favours different species to the interior. Small fragments are therefore unfavourable for those species which require interior habitat and may ead to the extinction of those species.
One popular solution to the problem of habitat fragmentation is to link the fragments by planting corridors of native vegetation. This has the potential to solve the problem of isolation but not the loss of interior habitat. Another solution is to enlarge small remnants in order to increase the amount of interior habitat, but this would be at the expense of reducing the degree of isolation.
Which is the best strategy for habitat reconstruction? Scientists at the Australian Museum are studying the arthropod fauna living in a variety of fragments and corridors to determine the configuration of habitats required to maintain species diversity. In addition, scientists are investigating the genetic composition of populations to determine the degree to which these populations are isolated from each other. The results of this project will help determine how important isolation and loss of interior habitat are as causes of loss of biodiversity. They will also lead to more strategic uses of resources for habitat reconstruction.
R Major
Terrestrial Ecology
Australian Museum
Copyright © Australian Museum, 2003
This page: http://www.amonline.net.au/factsheets/habitat_fragmentation.htm
