THE BIOLOGICAL SURVEY OF THE EASTERN GOLDFIELDS OF WESTERN AUSTRALIA: Vegetation and Flora

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Introduction: In Beard's (1975, 1980a) terms the Edjudina-Menzies Study Area falls mainly within the Austin Botanical District with a small part entering the Helms Botanical District. The main vegetation type in the Study Area is low woodland of Acacia aneura (mulga), as seen on the generalised map of Carnahan (1976) where it is depicted as Acacia tall shrubland with low shrubs. Trees or shrubs of Casuarina cristata (Belah) or Eucalyptus spp. (eucalypts) tend to replace mulga where the average annual rainfall is relatively high, as in the south-west of the Study Area, or where a deep friable soil occurs. The vegetation is low and open on shallow or salty soils. Where lime occurs close to the surface, the trees and tall shrubs are scattered and the main plant cover is formed by low shrubs of Maireana sedifolia (bluebush). This vegetation is described as lightly wooded succulent steppe by Beard (1975) and is extensive enough on Undulating Plains over basic rocks in the eastern central part of the Study Area to be mapped by Carnahan (1976) as Acacia tall open shrubland with low chenopodiaceous shrubs. On Hills mulga persists but is reduced to relatively low shrubs. On Salt Lake Feature the succulent steppe becomes very lightly wooded (Beard 1975) and the low shrubs are Atriplex spp. (saltbush). Both the mulga and the saltbush finally disappear on the bare beds of the salt lakes. Sandy soils are covered by Triodia basedowii (spinifex), forming a so-called shrub, or tree and shrub steppe (Beard 1975). The scattered shrubs are composed mainly of a Eucalyptus youngiana (mallee) and are joined on deep sands in the north-east of the Study Area by scattered trees of E. gongylocarpa (Marble Gum). This forms an area extensive enough to be mapped by Carnahan (1976) as shrub or tree steppe. The three main types of vegetation in the Study Area, as mapped by Carnahan, all occur in other Study Areas although his lightly wooded succulent steppe has a relatively limited extent.