|Goodrich, David - Dave|
Submitted to: Trans American Geophysical Union
Publication Type: Proceedings
Publication Acceptance Date: 3/1/1997
Publication Date: N/A
Technical Abstract: Landscape patterns metrics derived from remote sensing, spatial statistics, and geographic information systems technology were used to determine ecosystem vulnerability relative to large-scale natural or man-induced disturbances (e.g. climatic change and livestock grazing). Triplicate Landsat Multi-spectral Scanner imagery from the early 1970', mid-1980's, and early 1990's in addition to finer resolution imagery is utilized to generate land cover data and establish 20-year trends in conditions for the Upper San Pedro watershed in Sonora and Arizona. The approach is used to provide quantitative information on the large scale status of rangelands. Rangelands, such as those in the San Pedro are the most extensive land use of world drylands and it is estimated that 85% of the North American rangelands are in a degraded condition; more than any other continent. The evaluation determined that extensive grasslands with high connectivity were ethe most vulnerable ecosystem to fragmentation due to encroachment of wood shrubs and cacti as the number of grassland patches increased 61% and their average patch size decreased 60% between 1974 and 1987.