PARENT SESSION
Poster Session #16: Landscape Ecology I.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Time series piospheric analysis of grazing impacts .

WASHINGTON-ALLEN, ROBERT^*,1,3, VAN NIEL, THOMAS², WEST, NEIL³, RAMSEY, R. DOUGLAS³, ¹ DOE OAK RIDGE NATIONAL LABORATORY, OAK RIDGE, TN³ UTAH STATE UNIVERSITY, LOGAN, UT² LAND& WATER DIVISION, CSIRO, CANBERRA, ACT, AUSTRALIA

ABSTRACT- Separating the effects of land use practices from the influence of climatic variability is a monitoring problem in semi-arid and arid landscapes. Piospheres are indicators of localized impacts, such as livestock grazing, on vegetation and soils. A piosphere is a radiating zone of attenuating impact away from a concentrator, e.g, a watering trough or riparian corridor. Piospheres are characterized by increased soil erosion, reductions in vegetation cover, and changes in soil chemistry which can persist within a land management time cycle of 10 to 20-years. However, the long-term monitoring data required to detect these diagnostic features are rare. Archived Landsat satellite imagery represent a 30-year and continuing time series that are capable of detecting a piospheres diagnostic characteristics. A Geographic Information System (GIS) tool for conducting piospheric time series analysis was developed. The objectives of the analysis were to use a 26-year time series (1972 to 1997) of dry season vegetation inde x imagery from a commercially grazed ranch to (1) detect a piospheric response at both known piospheres that were occupied by water points and within riparian corridors that appear to be impacted by overgrazing from wild ungulates, and (2) to demonstrate the utility of the piospheric analysis program. We detected evidence of persistent degradation at water sources on the ranch, but not at streams. This GIS algorithm could be quite useful to land managers for separating the effects of climate from persistent degradation induced by localized disturbances. Future research will apply the analysis to examples of military and petroleum industry impacts. Oak Ridge National Laboratory is managed by the University of Tennessee Battelle LLC for the U.S. Department of Energy under contract number DE AC05-00OR22725.

KEY WORDS: PIOSPHERE, REMOTE SENSING, GIS, GRAZING