Extract from Hansard [ASSEMBLY - Tuesday, 26 November 2002] p3404c-3405a Mr Bernie Masters; Dr Judy Edwards

PLANT SPECIES, INDIGENOUS, STATISTICS ON DIVERSITY 370. Mr B.K. Masters to the Minister for the Environment and Heritage (1) Within the IBRA regions of Western Australia, what is the estimated number of vascular, indigenous plants within each region? (2) What other statistics exist to indicate the diversity of indigenous plant species within the major vegetation associations or more important ecosystems within the State? Dr J.M. EDWARDS replied: (1) The estimated number of native vascular plants in each IBRA region is shown in table below, based on the advice of the Western Australian Herbarium in the Department of Conservation and Land Management. Numbers of plant taxa within Western Australian IBRA bioregions Bioregion Number of Species Avon Wheatbelt 4140 Carnarvon 1389 Central Kimberley 1211 Central Ranges 678 Coolgardie 2348 Dampierland 1299 Esperance Plains 3250 Gascoyne 1163 Geraldton Sandplains 3135 Gibson Desert 591 Great Sandy Desert 738 Great Victoria Desert 816 Hampton 245 Jarrah Forest 3708 Little Sandy Desert 785 Mallee 3180 Murchison 2066 Northern Kimberley 1699 Nullarbor 413 Ord Victoria Plain 957 Pilbara 1497 Swan Coastal Plain 2774 Tanami 325 Victoria Bonaparte 1096 Warren 1789 Yalgoo 1229 (2) The biogeography program of the Department of Conservation and Land Management uses equal area quadrats to indicate species richness, however, these are not tied to major vegetation associations or ecosystems. They are normally stratified by surficial geology and landforms. 100m2 quadrats are used in heathland, wetlands or woodlands and normally 300m2 in semi arid, arid areas or forests. There are comprehensive data sets available, and published, for the Carnarvon Basin, parts of the Pilbara and Little Sandy Desert, Coolgardie, Avon-Wheatbelt, Mallee, Geraldton Sandplains, Warren, Jarrah Forest and Esperance Sandplain Bioregions. There is also information, based on sampling sites of approximate equal areas, for the Kimberley Rainforests, Limestone Ranges of the Kimberley, Eastern Goldfields, Nullarbor, Swan Coastal Plain and Geraldton Sandplains. Again most of this information is published. At a larger scale species lists for many islands, nature reserves, national parks and bushland areas, especially in southern Western Australia have been prepared which list plant species occurrences by vegetation type within the area. Over 200 of these lists are published and at least another 100 have been prepared. This would provide an indication of species richness at the scale of vegetation community. Finally three comprehensive listings of all individual plant species recorded have been checked and compiled for the Carnarvon Basin, Swan Coastal Plain and Warren Bioregions. These list all known flora records for the region and their conservation status.

[1] Extract from Hansard [ASSEMBLY - Tuesday, 26 November 2002] p3404c-3405a Mr Bernie Masters; Dr Judy Edwards

All of these data sources suggest that species richness is a common feature of many vegetation types in southern Western Australia. Species richness declines with declining and increasingly erratic rainfall in terrestrial sites. Ephemeral clay based wetlands are especially species rich in medium rainfall areas and their presence greatly increases a site's species richness.

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