Evaluating change in rangeland condition using multitemporal AVHRR data and geographic information system analysis

Coarse-scale, multitemporal satellite image data were evaluated as a tool f or detecting variation in vegetation productivity, as a potential indicator of change in rangeland condition in the western U.S. The conterminous U.S. Advanced Very High Resolution Radiometer (AVHRR) biweekly composite data s et was employed using the six-year time series 1989-1994. Normalized Differ ence Vegetation Index (NDVI) image bands for the state of New Mexico were i mported into a Geographic Information System (GIS) for analysis with other spatial data sets. Averaged NDVI was calculated for each year, and a series of regression analyses were performed using one year as the baseline. Resi duals from the regression line indicated 14 significant areas of NDVI chang e: two with lower NDVI, and 11 with higher NDVI. Rangeland management chang es, cross-country military training activities, and increases in irrigated cropland were among the identified causes of change.