|WEBB, NICHOLAS - New Mexico State University|
|Herrick, Jeffrey - Jeff|
|DUNIWAY, MICHAEL - Us Geological Survey (USGS)|
Submitted to: Acremonium Grass Interactions International Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/15/2014
Publication Date: 7/21/2014
Citation: Webb, N., Herrick, J.E., Duniway, M. 2014. Quantifying accelerated soil erosion through ecological site-based assessments of wind and water erosion. Proceedings of the Eighth International Conference on Aeolian Research (ICAR VIII), July 21-25, 2014, Lanzhou, China. p. 357.
Technical Abstract: This work explores how organising soil erosion assessments using established groupings of similar soils (ecological sites) can inform systems for managing accelerated soil erosion. We evaluated aeolian sediment transport and fluvial erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Our results show that sediment transport and erosion can be highly variable within and among ecological sites. Plots in shrub-encroached and shrub-dominated states were consistently susceptible to both aeolian sediment transport and fluvial erosion. However, grassland plots and plots with a grass-succulent mix had a high indicated susceptibility to wind and water erosion respectively. Vegetation thresholds for controlling erosion are identified that transcend the ecological sites and their respective states. The thresholds define vegetation cover levels at which rapid (exponential) increases in sediment transport and erosion rates begin to occur, suggesting that erosion in the study ecosystem can be effectively controlled when bare ground cover is <20% of a site or total ground cover is >50%. Similarly, our results show that erosion can be controlled when the cover of canopy interspaces >50 cm in length reaches ~50%, the cover of canopy interspaces >100 cm in length reaches ~35% or the cover of canopy interspaces >150 cm in length reaches ~20%. This process-based understanding can be applied, along with knowledge of the differential sensitivity of vegetation states, to improve erosion management systems. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of sites to erosion. Land use impacts that are constrained within the natural variability of sites should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds and natural variability of ecological sites will enable improved identification of where and when accelerated soil erosion occurs and the development of practical management solutions.