Wind Erosion and Dust Flux along the Grassland-Forest Continuum: Effects of Disturbance and Woody Plant Cover

Wind erosion and dust flux in and from dryland ecosystems operate over a range of spatial scales and have important implications for atmospheric, hydrologic, and biogeochemical processes. Wind erosion and dust flux are of particular importance in dryland ecosystems where ground cover is inherently sparse because of limited precipitation and high evaporative demand. A key consequence of sparser vegetation cover and drier soils is the potential for an increase in wind erosion and dust flux. Further, many dryland ecosystems are undergoing accelerated land degradation due to increased land-use activities, which have a large effect on erosional losses through aeolian and fluvial processes. Despite the fundamental importance of wind erosion and dust flux within these systems, relatively few measurements of aeolian sediment transport have been made over multiple wind events and across a variety of types of dryland ecosystems. Here we report new field-based measurements of aeolian sediment transport in disturbed and undisturbed semiarid grasslands in southern Arizona and compare our site-specific findings to other recently published measurements of aeolian sediment transport in dryland ecosystems along the grassland-forest continuum. Our site-specific results indicate that disturbance can have a large effect on aeolian sediment transport at the plot scale and that the type and intensity of disturbance plays an important role in determining the magnitude and the severity of the response. More generally, our findings suggest that for relatively undisturbed ecosystems, shrublands have inherently greater aeolian sediment transport than grasslands, woodlands and forests. Furthermore, the proposed framework suggests that for disturbed ecosystems, the upper bound for aeolian sediment transport increases as a function of decreasing woody plant cover. As a result, aeolian sediment transport spans a relatively small range in woodlands and forests, an intermediate range in shrublands, and the largest range in grasslands.