Native vegetation is defined as vegetation that is indigenous to a given state, including trees, shrubs, understory plants and some specified grasslands . The removal of native vegetation for urbanisation and intensive agriculture (e.g. grazing and cropping) has been substantial within the Intensive Landuse Zone in Australia .
The extent of catchment clearing was used as an indicator of habitat loss in the assessment catchment condition in Australia, during the National Land and Water Resources Audit .
Photo 1. The natural vegetation cover is relatively intact in the lower catchment of St. Mary's Inlet, WA (photo by Craig Smith).
Coastal issues arising from land clearing
Land clearing fragments the native bush, reducing its biodiversity and destroying its hydrological equilibrium [4,5]. Inorganic nutrient and fine sediment exports increase in response, particularly when the native bush of a catchment has been reduced by 50% . Impacts on coastal waterways may include:
Existing information and data
Maps showing 'native vegetation cover' can be found at the Catchment Condition Online Maps website at Agriculture, Fisheries & Forestry Australia . Appendix I (pp. 311-312) in Volume 2 of the Australian Catchment, River and Estuary Assessment, 2002 contains a map of Australia's River Basins and Drainage Divisions in which each river basin has been assigned a number. These catchment numbers can be matched to a large number of coastal waterways in pages 316-363 of the same document. The per cent native vegetation cover for the river basins is available in Appendix B (pg 65-76) of the Assessment of Catchment Condition in Australia's Intensive Land Use Zone: A Biophysical Assessment at the National Scale  . The extent of catchment clearance is a parameter in the Simple Estuarine Response Models developed by CSIRO.
More information on the importance of native vegetations can be found at the Australia's Native Vegetation Website at Environmental Australia.