Threatened plant communities of Western Australia. 2 The seasonal clay-based wetland communities of the South West

Abstract

The communities of seasonal clay-based wetlands of south-west Australia are described. They are amongst the most threatened In Western Australia. It is estimated that >90% of the original extent of these communities has been cleared for agriculture, and the remaining areas, despite largely occurring in conservation reserves, are threatened by weed invasion and rising saline groundwater. Thirty-six taxa are identified as claypan specialists occurring in six floristic communities. Composition was strongly correlated with rainfall and edaphic factors. The most consistent attribute shared between the seasonal clay-based wetlands of south-west Australia, and the analogous vernal pools systems of California, Chile, and South Africa was the widespread conversion of these wetlands to agricultural systems. The south-west Australia wetlands had a richer flora, different lifeform composition, higher species richness but fewer claypan specialists than the vernal pools of California. The dissimilarity in the regional floras and vegetation types from which the pool floras were recruited explain these differences.