FRACTIONAL COVER AND STRUCTURAL VARIATIONS ALONG A LAND USE DEGRADATION GRADIENT IN SAVANNAS IN AND AROUND THE KRUGER NATIONAL PARK, SOUTH AFRICA

摘要: Land degradation is one of the most significant environmental problems in the semi-arid and arid savannas of Southern Africa. Degradation affects vegetation structure, cover and patchiness and this result in the loss of vegetation resources used by rural populations (grazing, fuel wood, and other non-timber forest products) and wildlife. Land degradation processes are influenced by rainfall, land management, soil properties and topographic effects (through slope redistribution of water and nutrients). These aspects control the type and distribution of vegetation cover types and biological materials on the land surface. Our primary goal was to quantify variations in the vegetation fractional cover and structure along a land use degradation gradient ranging from conservation in the Kruger National Park (South Africa) to communal rangelands, using detailed airborne hyperspectral and discrete return LiDAR data. High resolution (1 meter) airborne high-fidelity hyperspectral imagery (visible–NIR) and LiDAR data were collected using the state of the art Carnegie Airborne Observatory (CAO) instrument (Asner) in April-May 2008. The sampling design considered variations in land use management types, geological substrates (nutrient-poor granite and nutrient-rich gabbro), and topographical positions (hill crest and valley bottom). Management types ranged from moderate use by wildlife in the Kruger National Park to heavier use by wildlife in adjacent private reserves (Sabi Sands Game Reserve), and light, medium, and heavy use by people and livestock in the rural areas, Bushbuck Ridge. The latter areas are widely regarded to be degraded following …