Remnant Vegetation

Large-scale vegetation clearing for agriculture has been the major cause of tree cover loss in the region, although urbanisation and clearing as part of mining and forestry activities has also contributed to this decline (but to a lesser extent).

Generally, remnant forests and woodlands of the region are confined to public land and some adjoining private land. Most of these areas are under threat from a range of pressures related to the fragmented nature of the vegetation combined with the types and scale of use of these areas.

In the regional context, substantial tree cover remains on public land in the northern Grampians National Park, Little Desert National Park and Mount Arapiles Tooan State Park. Elsewhere, fairly large tracts of vegetation still occur in association with the parallel sand dunes south of the Little Desert between Horsham and Edenhope. The Jilpanger Flora and Fauna Reserve is contained within this area while a number of forest blocks in this area have been proposed for reservation under the West Regional Forest Agreement (external link).

Away from these areas, most remnant native vegetation in the region is restricted to public land along the major tributaries that dissect the plains, including the Wimmera River. The structure and species composition of these areas has been altered by timber harvesting, domestic stock grazing and recreational pursuits while presently, weed invasions and altered flooding regimes pose a major threat to these vegetation types.

The extent of loss of native vegetation in the Wimmera since European settlement is illustrated below (adapted from DNRE, 1997).

Vegetation Types	Pre-European Area (ha)	% Remaining
Box-Ironbark Forest	5 232	38.9
Grassland	329 727	0.4
Heathy Woodland	106 210	57.5
Herb Rich Woodland	78 045	6.1
Inland Slopes Woodland	16 916	12.5
Plains Grassy Woodland	942 508	2.8
Riverine Grassy Woodland	6 486	0
Sedge-Rich Woodland	25 726	9.0
Wimmera Mallee Woodland	49 193	2.8

From this it can be seen that vegetation types associated with the region’s better agricultural soils, especially Grassland, Plains Grassy Woodland, Wimmera Mallee Woodland and Riverine Grassy Woodland have been extensively cleared for agriculture.

Presently, freehold land in the Wimmera retains only about 3% of its original native vegetation as generally scattered remnants. Therefore, roadsides and unused road reserves are particularly important in preserving remnant stands of native vegetation. Throughout parts of the Wimmera catchment region, grasslands occur only as small remnants where edge effects and continued clearing pose the greatest threat. Other threats to remnant grasslands include inappropriate tree planting into remnants, drift from aerial spraying and stock grazing without replacement of senescent trees (DNRE, 1997).

Remnant Vegetation was mapped using data from the TREE25 layer. The dataset was derived from the Department of Sustainability and Environment, Land Information Group, and was mapped by the Centre for Land Protection Research (CLPR). References Department of Natural Resources and Environment (the former DNRE), (1997). Victoria’s Biodiversity: Directions in Management, Department of Natural Resources and Environment, Melbourne.

False colour satellite imagery showing remnant vegetation in central Wimmera

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