Ecological site-based assessments of wind and water erosion: Informing accelerated soil erosion management in rangelands

Authors: WEBB, NICHOLAS - New Mexico State University; Herrick, Jeffrey - Jeff; DUNIWAY, MICHAEL - Us Geological Survey (USGS)

Submitted to: Ecological Applications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2014
Publication Date: 9/14/2014
Publication URL: http://handle.nal.usda.gov/10113/59627
Citation: Webb, N., Herrick, J.E., Duniway, M. 2014. Ecological site-based assessments of wind and water erosion: Informing accelerated soil erosion management in rangelands. Ecological Applications. 24:1405-1420.

Interpretive Summary: Land use change and intensification have resulted in accelerated rates of soil erosion and land degradation in many areas of the world’s rangelands. This paper explores how soil erosion assessments structured across ecological sites can inform systems for managing accelerated soil erosion in rangelands. We evaluated wind and water erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. The analysis enabled us to resolve the spatiotemporal variability in erosion controls and erosion rates across the sites, identify the potential impacts of a site disturbance (graded roadways) on erosion, and elucidate underpinning patterns and thresholds in erosion responses and how they manifest across the ecological sites and their respective states. 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.

Technical Abstract: This paper explores how soil erosion assessments structured across ecological sites can inform systems for managing accelerated soil erosion in rangelands. We evaluated wind and water 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 wind and water erosion can be highly variable within and among ecological sites. Plots in shrub-encroached and shrub-dominated states were consistently susceptible to both wind and water 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 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.