Nomination 377: Habitat Fragmentation as a threatening process.

The following is an extract from nomination 377, the final recommendation for listing of this threatening process into the Flora and Fauna Guarantee Act.

FINAL RECOMMENDATION ON A NOMINATION FOR LISTING.
Nomination 377

Description of process:

Habit fragmentation is the process by which natural habitats are subdivided leaving remnants amidst an altered landscape. The process involves: an overall loss of habitat, a reduction in size or remaining fragments; and increased separation and isolation of remaining figments by intervening land use.

Commonly observed examples of fragmentation in Victoria are patches of forest or woodland retained amongst rural landscape, and small natural areas amidst expanding urban environments. Fragmentation may also be visibly less obvious: for example, remnants of native grassland amongst introduced pasture grasses or remnants of old-growth forest amongst regenerating forest.

Impact on species:

Habitat fragmentation has a number of impacts on species populations. For some species, fragmentation isolates the resources that animals require on a daily or seasonal basis. With decreasing size of fragments, the size of populations that these can support also decreases. Small populations are particularly vulnerable to fluctuation and extinction due to chance events (demographic, Genetic, environmental, catastrophes) and over time they disappear from remnant habitats. Many fragments are too small to support even single individuals of species that require large territories.

Impact on Evolutionary development:

At the level of whole communities, fragmentation results in the loss of species, changes to the composition of assemblages and changes to ecological processes. There is widespread evidence that habitat fragmentation results in the decline and loss of species from fragments, and that such losses may lead to local and regional extinctions. Changes resulting from fragmentation are not immediate, but become evident over years or decades as, for example, animal populations slowly decline to extinction on local then regional scale, tree regeneration fails and trees eventually die without replacement, plant population decline from lack of dispersal, etc.

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