CHARACTERISTIC SPECTRAL REFLECTANCE OF A SEMIARID ENVIRONMENT

Comprehensive information on the spectral reflectivity of several dese rt habitats and of dominant desert vegetation are presented. No previo us high resolution spectral reflectance measurements were made in this semi-arid Sahara-Arabian phytogeographic zone. Due to the relative ho mogeneity of the region, in terms of terrain type and comprehensive sa mpling, the local scale surface albedo was estimated to be about 30-33 per cent. It was also possible to revisit the currently accepted hypo thesis on the observed contrasts in surface reflectivity between prote cted and overgrazed areas. It seems that anthropogenic activities, whi ch prevent the accumulation of crust or destroy an existing crust, rat her than the overgrazing mechanism itself, are the main reasons for th e sharp contrast between the protected and overgrazed surfaces.