Habitat fragmentation and wildlife corridors

By Murray Ralph

Since European settlement, over 60% of Victoria’s native vegetation has been cleared. This widespread loss of habitat has had devastating impacts on our native plants and animals, and natural ecosystems. Widespread clearing has also resulted in remaining native vegetation becoming highly fragmented in many areas, placing further pressure on native species and ecological processes. The feeding and breeding cycles of many native animals have been severely disrupted, including the dispersal of young animals into new territories.

Fragmentation also effects the ability of many native animals to find refuge from wildfires and prolonged drought, or to recolonise areas following these events. Pollination of many native plant species by birds and insects, and seed dispersal, have also been severely restricted by fragmentation.

Habitat fragmentation also affects the maintenance of genetic diversity, especially for native plants and animals that are confined to smaller or isolated patches of bush. In such circumstances species become prone to inbreeding as the distance from other remnants prevents the inflow of new genetic material. The capacity of natural ecosystems to adapt to large-scale environmental change, such as climate change, is also severely reduced by the fragmentation of habitat. The current levels of fragmentation will be a major impediment to native plant and animal communities adapting to any future changes, especially human-induced climate change.

If native ecosystems are to survive and flourish into the future we must protect remaining habitat and restore the connectivity of habitat within the landscape. The establishment of a network of wildlife corridors (also called biolinks) on a landscape scale is one key way we can redress habitat fragmentation. The design of corridors will depend on the types of native animals that are likely to use them. For example, research indicates that Sugar Gliders will use a 40m wide corridor, whereas Yellow Bellied Gliders require an 80m wide corridor. Very narrow corridors tend to be of limited value for most species. It should also be recognised that not all native fauna will use corridors.

The most appropriate locations for biolinks are best considered at a landscape level using aerial or satellite photographs. Corridors should link existing larger patches of native vegetation, such as State or National Parks. In connecting these larger remnants, corridors should also incorporate existing smaller patches of native vegetation on streamside reserves, private land and roadsides.

Streamsides and gullies are some of best locations to place biolinks as they are more fertile areas, and therefore more productive for wildlife. They also tend to have more complex vegetation and habitat than surrounding areas. However, research indicates that more native animals are recorded in corridors that also provide links to other parts of the landscape, such as ridges.