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