Wind Erosion in Western Queensland Australia

Chapter 1 - IntroductionMitchell Grass Downs (245 635 km 2 ):The Mitchell Grass Downs bioregion is characterised by undulating grassland downs. Thebioregion lies across the headwaters of the river systems flowing through the ChannelCountry. Soils are predominantly grey and brown cracking clays (vertosols) that are selfmulchingduring wet-dry cycles. This bioregion supplies the fine silts and clays that aredeposited on the lower river floodplains following periodic flood events. To the west of thebioregion rudosols and chromosols are found on the low ranges separating the Georgina andDiamantina river catchments. The dominant vegetation in the bioregion includes the Mitchellgrasses (Astrebla spp.), which cover the expansive open downs (Figure 1.5). Tree cover issparse or absent from much of the bioregion, however stands of Gidyea (Acacia cambagei)and Boree (Acacia tephrina) are found in the eastern parts of the bioregion, particularly ondissected ridgelines bordering the Channel Country.Figure 1.5 Images of the Mitchell Grass Downs showing (a) grassland pasture during a winterdrought, (b) the same location following 100 mm rainfall in one month, (c) degraded pasture west ofthe Diamantina River, and (d) pastures and mesas to the northeast of the northeast of the DiamantinaRiver. Stands of Gidyea trees can be seen in (b), (c) and (d)18