Indicators of rangeland change and their potential for remote sensing

Selected environmental variables were evaluated for their utility as indicators of rangeland change and their potential for remote sensing. Fifty-nine study sites were sampled in southern New Mexico. Total vegetation cover and the ratio of shrub cover to grass cover were related to disturbance. Increasing degrees of change were associated with a decrease in total vegetation cover, an increase in the ratio of shrub to grass cover and a decrease in organic soil cover (litter and algal crusts). Total vegetation cover and organic soil cover can be monitored from single-date satellite data, but total vegetation cover alone may provide ambiguous results. The ratio of shrub to grass cover, which is necessary to identify the direction of change can be determined by examining multi-date satellite data that correspond to the times when grasses and shrubs exhibit their maximum green biomass.