Enormous amounts of time and money are contributed by researchers, government, the private sector and volunteers to protect or enhance vegetation condition. But what exactly is vegetation condition? Any statement about the condition of something must be made in relation to something else, i.e., my old car is in much worse condition than when it was new, or is in worse condition than my friend’s car.
Vegetation condition is commonly compared to what the vegetation was like before European settlement or ‘pre-1750’ vegetation. The only catch is that we don’t know exactly what the vegetation was like then. In Victoria we have tried to estimate this condition through surveying the best representatives of each vegetation type (or each Ecological Vegetation Class – EVC) that remain today. These best condition estimates are stated as ‘benchmarks‘ for each EVC and listed on the Department of Sustainability and Environment (DSE) website.
So once you have a benchmark or something to compare against, how do you evaluate vegetation condition at a site? DSE’s version is called Vegetation Quality Assessment (VQA). They have scored a range of attributes within the benchmark sites to give a VQA score for each EVC. This method is based on the ‘habitat hectares’ method described by Parkes et al. (2003). Vegetation that has been scored using the VQA method can be compared against its relevant benchmark and assessed appropriately. There is a bit more to it than this, but you get the idea.
A similar benchmark comparison tool for assessing vegetation condition exists in NSW called BioMetric, developed by Gibbons et al. 2005 and 2009.
But this is not the only, nor necessarily the best way to assess condition. Some landscapes have been modified so much by people, or by changes in the climate itself, that trying to restore the vegetation to its ‘original’ condition is either impossible or far too expensive. At what point is it worth giving up on trying to restore a site to its original condition and instead setting a new benchmark that is more suited to the current attributes of the site? How would we set these new benchmarks?
We need to have targets for management but the benchmarks we set must be appropriate and realistic. I’m hoping some of my work will help to address parts of these questions and stimulate continued thought on this very necessary topic.
Gibbons, P., Ayers, D., Seddon, J., Doyle, S., Briggs, S. (2005). BioMetric Version 1.8. A Terrestrial Biodiversity Assessment Tool for the NSW Property Vegetation Plan Developer. Operational Manual. Department of Environment and Conservation (NSW), unpublished.
Gibbons P., Briggs S. V., Ayers D. A., Doyle S., Seddon J., McElhinny C., Jones N., Sims R. & Doody J. S. (2008) Rapidly quantifying reference conditions in modified landscapes. Biological Conservation 141, 2483-93.
Gibbons P., Briggs S. V., Murphy D. Y., Lindenmayer D. B., McElhinny C. & Brookhouse M. (2010) Benchmark stem densities for forests and woodlands in south-eastern Australia under conditions of relatively little modification by humans since European settlement. Forest Ecology and Management
Parkes D., Newell G. & Cheal D. (2003) Assessing the quality of native vegetation: The ‘habitat hectares’ approach. Ecological Management and Restoration 4, S29 – S38.