Southern Highlands and Plains (Environmental Region 4.1)
This region consists of 21 environmental associations. It encompasses the southern section of the uplands along the east coast of Eyre Peninsula, and the undulating to low hilly plains to the west. The western boundary represents a change from duplex soils and loams on the hilly or undulating country to sands on the plains to the west across the transition from calcrete to calcarenite plains. To the north the inland dunes form a distinct landform boundary. The uplands rise abruptly from a narrow coastal foreland to altitudes of between 200 m and 400 m but slope gradually to the west where they merge into the undulating plain. The eastern and highest section of the uplands is formed of metasediments, predominantly quartzite, and is mainly hilly while the slightly lower-lying western part constitutes a dissected laterite plateau. Moderately deep yellow duplex soils with lateritic concentrations occur on these uplands, which have a characteristic vegetation of low open forest or woodland or sugar gum (E. cladcalyx), peppermint box (E. odorata) and blue gum (E. leucoxylon). The plains to the west and south are formed predominantly on old alluvium, or on calcarenite near the coastal fringe where some dunes and cliffs occur. Shallow reddish loams with much rock outcrop support mallee broombush (E. incrassata - Melaleuca uncinata) on the plains or a woodland of dryland teatree (M. lanceolata) along the coastal fringe. The region has a great variety of views, often juxtaposed within short distances. Therefore, in contrast to the other regions of the province, visual resource descriptions are given for each association. There is a mild climate with a winter rainfall maximum and dry summers. Mean annual rainfall varies from about 350 mm in the north-east to about 550 mm in the south, with most of the rainfall occurring between April and October. Temperatures range from mild in summer to cool to cold in winter. Mean monthly evaporation is high in summer, but falls below the median monthly rainfall during winter. Mean annual evaporation increases from about 1700 mm in the south to about 1900 mm in the north.
