PARENT SESSION
Oral Session #12: Landscape Ecology: Theory and application. Presiding: C. Johnston.
Monday, August 6, 2001. 1:00 PM to 5:00 PM. Madison Ballroom D.
Remote sensing of soil erosion for monitoring the ecological integrity of rangelands.
WASHINGTON-ALLEN, ROBERT1,2, WEST, NEIL1, RAMSEY, R. DOUGLAS1, VAN NIEL, THOMAS3, 1 2 3
ABSTRACT- Soil erosion hazard maps are based on indicators measured by expensive field studies that have limited capacity to capture the variability of heterogenous landscapes. Satellite remote sensing provides a cheap synoptic approach for capturing this variability. The soil stability index (SSI) was derived from the spectral capability of Landsat imagery to discriminate between erosional, stable, and depositional surfaces in arid landscapes. A study was conducted to validate the use of the SSI in sagebrush steppe rangelands and to characterize its trend and response to livestock grazing and climate from 1972 to 1997. Our study site was a commercially grazed ranch in northeastern Utah. We hypothesized that soil physical characteristics, specifically organic matter (om) and clay content (cl), available water capacity (AWC), soil erosion [wind erosion index (wei)] and erodibility (kw factor), would vary with erosion status. We found om, cl, and AWC (r = 47) and both kw (r = .11) and I (r = .19), were significantly correlated with SSI. The SSI trend was stable from 1972 to 1997 and was moderately correlated with climate change and grazing, i.e., under drought, particularly strong El Niņo events, and high grazing pressure the landscape became more susceptible to erosion.
KEY WORDS: soil erosion, soil stability index, remote sensing, timeseries