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A spatial dynamic framework for landscape-scale assessment of accelerated wind erosion in Australian rangelands

Helene Aubault 1 ,4, Nicholas Webb2, Craig Strong3, Grant McTainsh4
1Loughborough University, Loughborough, UK, 2USDA-ARS Jornada Experimental Range, Las Cruces, USA, 3Australian National University, Canberra, Australia, 4Griffith University, Brisbane, Australia

An estimated 110 Mt of dust is eroded by wind from the Australian land surface each year, most of which originates from the arid and semi-arid areas. Livestock production is a major activity in these areas and can increase their susceptibility to wind erosion by further reducing vegetation cover and modifying surface soil stability. While accelerated wind erosion is widely accepted to exist, the scale of grazing impacts in rangelands is still largely debated, because pastoral land management activities have received less research attention than cultivated land management. To date, most methods used to assess the impacts of pastoral activities on wind erosion have been made limited progress in discriminating accelerated wind erosion, due to: 1) their broad spatial and/or temporal resolutions and 2) the scarcity of data on the effects of spatial and temporal variations of land management impacts on land erodibility. In addition, the outcomes of these broad scale studies have seldom been translated into recommendations that are relevant for land managers.
Here, we present a framework developed to assess accelerated wind erosion at landscape scale. The framework combines soil erodibility, vegetation and grazing intensity data in a Geographical Information System to quantify land erodibility and accelerated erosion risk on different land types. Land erodibility is defined using process-based relationships, integrating vegetation cover and erodible soil fraction. Grazing intensity is determined by the distance from the livestock watering points. For every time period, the land erodibility of a landscape is compared to a reference time period, when erodibility was primarily influenced by climate conditions. Accelerated wind erosion risk maps are produced for each land type.
We apply the framework to multiple land types in rangelands of western Queensland in Australia. Our results show that the risk of accelerated erosion is much greater during drier periods than in wetter periods. Up to 84% of the landscape evidenced accelerated erosion in dryer periods, whereas in wetter periods less than 10% of the landscape displayed some level of accelerated erosion. Overall, the grazing gradient-wind erosion framework produces encouraging results; overcoming three limitations of previous methods for assessing accelerated erosion, by: 1) accounting for spatio-temporal variations of land management, 2) integrating a soil erodibility component which includes the effect of trampling, and 3) operating at a landscape scale to increase its functionality for land managers.