Remote Sensing-Based Piosphere Analysis

The term piosphere was orginially defined as an indicator of the localized impact of grazing on vegetation and soils. It is a radiating zone of attenuating animal impact away from a concentrator, e.g, water, mineral licks, bedding grounds, etc. Over time there may be increased soil erosion, reductions in vegetation cover and changes in soil chemistry within piospheres. This paper expands this definition to include any concentrated animal or anthropogenic impact that radiates from an area of concentration. Satellite remote sensing instruments are capable of detecting both broad-scale climatic effects and small-scale localized impacts. A remote sensing-based tool for conducting piospheric analysis was developed to help evaluate areas of landscape impact caused by livestock or other concentrators. The program characterizes a piospheric response using three GIS layers: a boundary (e.g., a paddock); a concentrator (e.g., a water source); and a response index (e.g., a remotely sensed vegetation index). Piospheric analysis was demonstrated within a grazing paddock that had obvious piospheres. The objectives of the analysis were to: (1) use a time series of dry-season vegetation index imagery from 1972 to 1997 to characterize the historical vegetation response and relate it to climate and grazing at the paddock spatial scale; (2) characterize vegetation response at water points and streams; (3) determine if piospheres can be detected in sagebrush steppe; and (4) demonstrate the utility of the piospheric analysis program. Evidence of persistent degradation at water sources was detected but not at streams. This type of analysis could be quite useful to land managers for separating the effects of climate from persistent degradation induced by localized disturbances.