HR: 0800h
AN: B11B-0156    [Abstracts]
TI: Assessing the effect of human-induced land degradation on ecosystem function in the former homelands of South Africa
AU: Wessels, K J
EM: wessels@geog.umd.edu
AF: Geography Department, University of Maryland Room 2181 LeFrak Hall, College Park, MD 20742-8225 United States
AU: * Prince, S D
EM: sprince@geog.umd.edu
AF: Geography Department, University of Maryland Room 2181 LeFrak Hall, College Park, MD 20742-8225 United States
AB: The communal homelands in north-eastern South Africa, created during the apartheid-era, are widely regarded as severely degraded as a result of human utilization. The impacts of degradation on net primary production (NPP) were studied using a time-series (1985 to 2003) of Advanced Very High Resolution Radiometer (AVHRR) NDVI and modeled NPP data for degraded rangelands identified by the National Land Cover (using Landsat TM imagery) and non-degraded rangelands within the same land capability units (LCUs). The NPP of degraded areas was significantly lower than in non-degraded parts of most of the LCUs and the difference between degraded and non-degraded areas did not diminish in years with high rainfall, although NPP in degraded areas in wet years exceeded that of non-degraded areas in drier years. Thus degraded areas had the same resilience as non-degraded areas. The Rain-Use Efficiency (RUE) of degraded areas (NPP per unit rainfall) was also consistently lower than non-degraded areas. The persistence of the effect on the NPP indicated that the degradation is stable at the time scale of 18 years. These results indicate that, while there has not been a catastrophic reduction in ecosystem function within the former homelands, degradation results in a stable state with reduced productivity and RUE. The results highlight the importance of multi-temporal analyses of ecosystem function to understanding land degradation and illustrate how long time-series of terrestrial data might be used in a national land degradation monitoring system.
DE: 1803 Anthropogenic effects
DE: 1809 Desertification
DE: 1851 Plant ecology
DE: 1640 Remote sensing
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting