Overview of plot-based vegetation classification approaches within Australia

We review vascular plant plot survey data, plot-based terrestrial vegetation classification protocols and schema by state and bioregions across Australia, discussing recent regional approaches in States and bioregions. A high degree of inconsistency exists in vegetation classification methods and management of plot data across jurisdictions and Australia currently lacks a unified national vegetation plot database, vegetation plot-recording protocols and agreed thematic outputs for classification. Broad-scale classifications were developed largely to support vegetation mapping based on remote sensing of image patterns. Since the 1970s, plot datasets from well-sampled regions have been subjected to a range of analyses (sometimes numerical) producing finer-scaled but idiosyncratic classifications. There are robust numerical classifications for less than 5% of the Australian continent. In poorly sampled and plot-free regions, vegetation classification has focussed on expert description or hybrid approaches using patchy quantitative outputs where they exist. A rigorous quantitative continental regional to local scale approach to classification will not be possible until major data gaps are filled. Additionally, the impact of Australia's inconsistent rainfall on species composition and abundance in analyses of combined datasets requires careful consideration. Given that vegetation classification is integral to Australian biodiversity laws and regulations, there would be benefits in extending quantitative plot coverage to data-poor areas, encouraging cross jurisdictional co-operation of classification procedures, promoting the use of comparable methodologies and sampling under different disturbance and climatic regimes. The development of a consistent vegetation classification across Australia will also require inter-state co-operation, higher standards of plot data curation and plant taxa nomenclature, agreed nation-wide classification protocols and a scientifically defensible hierarchical classification that should integrate with the International Vegetation Classification (IVC).