Author:Wessels, Konrad J; Prince, SD; Frost, PE; Van Zyl, DDate:15 May 2004There is a pressing need for an objective, repeatable, systematic and spatially explicit measure of land degradation. In northeastern South Africa, there are large areas of the former homelands that are widely regarded as degraded. A time-series ...Read more
Author:Wessels, Konrad J; Prince, SD; Malherbe, Johan; Small, J; Frost, PE; Van Zyl, DDate:Jan 2007Advanced Very High Resolution Radiometer (AVHRR), Normalized Difference Vegetation Index data (NDVI, I km (2), 1985-2003) and modelled net primary production (NPP, 8 km (2), 1981-2000) data were used to estimate vegetation production in South ...Read more
Author:Wessels, Konrad J; Van den Bergh, F; Scholes, RJ; Miteffa, SDate:Apr 2011There has been a recent proliferation of remote sensing-based trend analysis for monitoring regional desertification. These show contradictory results. All of them claim to have been “validated” through expert interpretation, in the absence ...Read more
Author:Wessels, Konrad J; Prince, SD; Zambatis, N; Macfadyen, S; Frost, PE; Van Zyl, DDate:Mar 2006The relationship between multi-year (1989-2003), herbaceous biomass and 1-km(2) Advanced Very High Resolution Radiometer (AVHRR) Normalized Difference Vegetation Index (NDVI) data in Kruger National Park (KNP), South Africa is considered. The ...Read more
Author:Wessels, Konrad J; Prince, SD; Carroll, M; Malherbe, JohanDate:Apr 2007According to the nonequilibrium theory, livestock grazing has a limited effect on long-term vegetation productivity of semiarid rangelands, which is largely determined by rainfall. The communal lands in northeastern South Africa contain ...Read more
Author:Wessels, Konrad J; Steenkamp, Karen C; Von Maltitz, Graham P; Archibald, SDate:Feb 2011What are the patterns of remotely sensed vegetation phenology, including their inter-annual variability, across South Africa? What are the phenological attributes that contribute most to distinguishing the different biomes? How well can the ...Read more
Author:Steenkamp, Karen C; Wessels, Konrad J; Archibald, S; Von Maltitz, Graham PDate:May 2009Remotely-sensed phenological metrics (or phenometrics) were derived from AVHRR vegetation-index time-series data and to describes seasonal growth in terms of start, end, length of season and estimates of net primary production (NPP). This ...Read more