Northern Complex (Environmental Region 6.2)
This region consists of 12 environmental associations. The Flinders Ranges here are wider than to the south, and branch into a broader north-eastern and narrower north-western section. Quartzite hogbacks are still present but represent a smaller proportion of the region than do the lower ridges and hills on softer rocks. Intermontane plains and the associated red duplex soils are less prominent than in region 6.1. There has been less obvious degradation of the natural vegetation than in region 6.1. However the plains and much of the area of low hills and ridges appear to have suffered from clearing and periodic overgrazing. Here open woodlands of black oak (Casuarina cristata), bullockbush (Heterodendrum oleifolium), mulga (Acacia aneura) and native pine (Callitris columellaris) alternate with mallee scrub (E. socialis), tall shrublands (e.g. Acacia spp., Eremophila spp. and Cassia spp.) and tracts of sparse chenopod shrublands of Maireana spp. and Atriplex spp. with seasonal grasses and forbs. Two introduced species have become characteristic seasonal forbs in this region. They are Salvation Jane or Paterson's curse, (Echium lycopis) and wild hops (Rumex vesicarius) which in some years carpet the plains and low hills in a spectacular display of colour. The quartzite hogback ridges are sparsely wooded with black oak, mulga and some native pine. These species extend down to lower slopes and valleys where they occur with mallee species (e.g. E. socialis) and tall shrubs such as Acacia rivalis and elegant wattle (A. victoriae). Native orange (Capparis mitchellii) and a native poplar (Codonocarpus pyramidalis) occur on the slopes of these ridges. River red gum, (E. camaldulensis) is the dominant species on valley floors where coolibah box (E. intertexta) and teatree (Melaleuca glomerata) are also common. The fans and footslopes in the west mainly carry a bluebush shrubland (e.g. Maireana astrotricha, M. pyramidata) with seasonal grasses and forbs. Native fuchsia (e.g. Eremophila freelingii, E. scoparia) and birdseye (e.g. Cassia eremophila, C. sturtti) occur in tall shrublands over the bluebush or over sparse seasonal vegetation. Open woodlands of black oak or false sandalwood (Myoporum platycarpum) also occur. In the east the fans also carry a chenopod shrubland of saltbush (Atriplex spp. and Rhagodia spinescens) and bindyi (Bassia spp.) with bluebushes (e.g. Maireana aphylla, M. excarata). Grasses such as Mitchell grass (Astrebla pectinata), blackheads (Enneapogon spp.) and lovegrass (Eragrostis spp.) are also common, sometimes mixed with other chenopods and sometimes particularly in the north as grasslands. Tall shrublands of elegant wattle occur close to creeks. The views in the south-east and far west of this region are the same as those in region 6.1, i.e. foreground to middleground panoramas and perspectives dominated by abrupt ridges, detailed and enclosed views along watercourses and valleys and panoramas from the ridges, though sparser vegetation here alters the colour and contrast. In the central west, however, between Mt. Fitton and Copley in Yerelina and Barilla associations, the views open out to middleground and background panoramas, locally dominated by hills or ridges, including the ridges of adjacent associations to the east and south. The climate is mild to hot in summer and cool to cold in winter. Rainfall is low and unreliable throughout the year, with the highest monthly falls generally occurring in winter. Mean annual rainfall increases from 150 mm in the north to between 300 and 350 mm in the ranges in the south. Mean monthly evaporation is very high in summer and exceeds the 90th percentile of monthly rainfall throughout the year. Mean annual evaporation increase from 2800 mm in the south to about 3600 mm in the north. Temperatures show high seasonal and diurnal variation.
