A study designed to determine the variation in the composition of the vegetation on the coastal Holocenes and deposits between Perth and Geraldton is described. The study was based on 545 sites at which descriptions of the geology, landform, soil and vegetation and a complete list of flora were made.The floristic composition of these sites varied considerably. Numerical classification showed some quite distinct communities and others which seemed part of a multi-dimensional continuum. Several factors appeared to be instrumental in the variation in composition. Landforms (incipient fore dunes, dunes or plains) were a major factor. So too were proximity to the coast, age (time since colonisation), geology and soiltypes. Relatively consistent regional variation in species composition was detected across a range of landforms and vegetation types. Based on this, five Sectors were recognised. The major influence on the Sectors appeared to be the variation in the Pleistocene deposits (Tamala Limestone and Cliff Head deposit) from which some of the Holocene sands were derived and over which some has been deposited. It was concluded that a similar degree of regional variation in the composition of vegetation could be expected on the coast elsewhere in south-western Australia. The variation in the Pleistocene and older rockand sediment types could be used to predict the variation on the Holocene deposits. While the vegetation of Holocene deposits are significantly poorer in species than the rich kwongan areas, over 300 native species were recognised in the Central Coast. A large proportion of these were confined to coastal areas. However, only a few species were endemic to the Central Coast, most being widespread in south-western or southern Australia. There was a significant replacement of species from Sector to Sector as the Central Coast represented the end of the range (north or south) for over 100 of these coastal species. This turn over of species contributed to the regional variation in composition.
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Western Australia, Vegetation Survey
Griffin, E.A. (1993) Flora of the Quindalup Dunes between the Swan and Irwin Rivers, Western Australia. Unpublished report to the Coastal Planning Branch, Department of Planning and Urban Development and the Heritage Council of W.A.
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