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Wind Erosion in Western Queensland Australia

Modelling Land Susceptibility to Wind Erosion in Western ... - Ninti One

Modelling Land Susceptibility to Wind Erosion in Western ... - Ninti One

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Chapter 1 - IntroductionChapter 1Introduction1.1 Introduction to ThesisApproximately 47% of the world’s land surface is classified as drylands (Thomas, 2000).This area <strong>in</strong>cludes dry sub-humid, semi-arid, arid and hyper-arid regions. The drylands arecharacterised by low precipitation – high potential evapotranspiration ratios and sparsevegetation cover (UNEP, 2008). These conditions result <strong>in</strong> a deficiency <strong>in</strong> soil moisture andlarge areas of bare ground, mak<strong>in</strong>g the regions particularly sensitive to climatic changes,anthropogenic disturbance and land degradation.<strong>W<strong>in</strong>d</strong> erosion is a land degradation process that affects dryland environments. It affectsapproximately 28% of the global land area experienc<strong>in</strong>g land degradation (Oldeman, 1994;Callot et al., 2000; Prospero et al., 2002). While w<strong>in</strong>d erosion is a naturally occurr<strong>in</strong>g process<strong>in</strong> many regions, it has been accelerated by human activities <strong>in</strong> rangelands and <strong>in</strong> marg<strong>in</strong>alcultivated lands. Anthropogenic pressures accelerat<strong>in</strong>g w<strong>in</strong>d erosion <strong>in</strong>clude overgraz<strong>in</strong>g ofrangeland pastures and the use of long-fallow<strong>in</strong>g of cultivated lands (Leys, 1999). While <strong>in</strong>many developed countries cultivation practices have been improved to m<strong>in</strong>imise soil loss dueto w<strong>in</strong>d erosion, there rema<strong>in</strong>s considerable graz<strong>in</strong>g pressure on rangelands. Arid and semiaridrangelands cover approximately 45% of the world’s land surface (Reid et al., 2008). Theeffects of graz<strong>in</strong>g on the rangelands are seen through a reduction <strong>in</strong> vegetation cover (due toconsumption), and the disturbance of soil crusts which play a critical role <strong>in</strong> reduc<strong>in</strong>g theerodibility of soils <strong>in</strong> arid and semi-arid environments (Belnap and Eldridge, 2001).<strong>W<strong>in</strong>d</strong> erosion has numerous on- and off-site effects. These are seen from the <strong>in</strong>dividual fieldscale (10 3 m 2 ) to regional (10 4 km 2 ) and global scales. On-site effects of w<strong>in</strong>d erosionrelevant to agriculture <strong>in</strong>clude (after Leys, 1999; McTa<strong>in</strong>sh and Strong, 2007):• Loss of nutrient rich topsoil <strong>in</strong> lands with generally nutrient poor soils;• Selective removal of f<strong>in</strong>e fraction particulates and organic matter from soils;1

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