Native Vegetation Net Gain Accounting - First Approximation Report
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This report provides a ‘first approximation’ account of progress with the Government’s Net Gain objective for native vegetation across Victoria. Net Gain Accounting - First Approximation Report(PDF - 1.9 MB) The distribution and quality of the remaining native vegetation in Victoria varies considerably across the State, and as part of this Net Gain Accounting, DSE has prepared an improved map of the extent of native vegetation which captures more detail (e.g. scattered trees) and more types of vegetation (e.g. native grasslands) than previously available mapping. Additionally, for the first time in Australia, a statewide map of the quality of native vegetation has been prepared based on advanced modelling techniques and site data from surveys and related government programs. The accounting measure is based on the Habitat Hectares metric, a scoring method that compares the presence of physical attributes at sites with reference points (benchmarks) for each vegetation type (100's in Victoria), and is designed to allow the combination of information on extent and quality, and comparison across all vegetation types. In largely-natural landscapes, disturbances like fire and flood cause vegetation site condition to fluctuate with respect to these benchmarks but these changes are currently treated as a net neutral for the purposes of this account. In fragmented landscapes, vegetation extent may be lost (through clearing) or gained (through revegetation); clearing by permit will be offset with the expectation of a neutral outcome; and, vegetation quality may be lost (through use or degradation) or gained (through changes to management). Whilst acknowledging the data limitations of this ‘first approximation’ analysis, the following summary figures (representing the 2005-2006 year) are provided and explained in the report:
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* due to significant uncertainties associated with the underlying assumptions, particularly about the amount of vegetation in each of the categories, these figures may be under- or over-estimates, possibly up to 20%
The report provides insights into the relative amounts and rates of positive and negative contributions. It also provides a basis for considering the strategic balance and effectiveness of programs. Changes in the quality of native vegetation are the major source of overall native vegetation change because they typically occur over extensive areas. On public land, processes that can cause on-going degradation of vegetation include weed invasions and inappropriate grazing regimes, which may arise from pest animals, excessive populations of native grazers, or licenced stock grazing. Small reserves, roadsides and river frontages are particularly affected. On private land, the same pressures exist, and there are also a range of entitled uses of native vegetation (e.g. timber for personal use, grazing and stock management) which can also lead to reduced levels of vegetation condition. Positive changes come from government programs and independent landholder activities which focus both on revegetation and on changing the management of existing native vegetation, either to actively improve site condition or to avoid further risk of damage.
Clearing of native vegetation also contributes to overall change, however given the previous extent of clearing and the regulated process for new clearing, this is no longer the largest source of native vegetation change in Victoria. A key result is that the estimated rate of clearing of woody native vegetation is similar if not reduced from the rate identified in an early 1990’s assessment. The cautious statement is because the two figures are not directly comparable due to changes in measurement technologies. The rate of clearing of grassy native vegetation is approximately 3,200 ha per year. This is the first time there has been a quantitative statewide insight into this issue, although it accords with anecdotal observations of regional staff. Most of this is due to conversion from native pasture grazing to more intensive agriculture, and this is usually in areas of lower quality native grassland.
The key issues identified in the report include:
- continuing concerns with the protection and management of endangered native grasslands;
- further effort is required to reduce the gap between the current rate of loss (particularly of site condition) and the current rate of investment in targeted incentives programs;
- addressing the current limitations to reporting by more systematic and complete capture of information on decisions and actions relating to native vegetation;
- stronger application of strategic priorities for intervention, particularly with respect to the emerging risks associated with climate change.
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