High temporal resolution analysis of land degradation in the northern Chihuahuan Desert using satellite imagery

In the middle 1800's, much of the northern Chihuahuan Desert was dominated by grassland. Since that time land degradation in this region, identified as the invasion of grasslands by desert scrub species, has been widespread and well documented. Our limited understanding of the processes involved in land degradation, however, inhibits our ability to understand, monitor, and model ecosystem health and vulnerability to degradation. This research increases our understanding by characterizing temporal landscape processes and evaluating regional landscape parameters derived from high temporal resolution satellite data and determining their utility in mapping, monitoring and modeling landscape health and degradational processes.; Temporal growth characteristic curves were derived from satellite data for 1987 through 1993. Differences in growth characteristics were evaluated for plant communities at various stages in the degradation process. Satellite-derived measures of vegetation growth, spatial variability, surface brightness, temporal patterns, and magnitudes were compared with field cover and composition measures for twenty sites at varying levels of degradation. Comparisons with precipitation measures were also conducted.; It is concluded that with carefully calibrated, high temporal resolution satellite data, it is possible to detect plant community composition shift from grasses to shrubs that is indicative of land degradation in the northern Chihuahuan Desert. Additionally, because of the relationship between precipitation and plant growth, the satellite-derived measures are also useful for monitoring moisture stress and moisture status across the landscape.