Determining grazing capacity in Namibia with the aid of remote sensing

Abstract

The Namibian rangelands consist of a mixture of herbaceous and woody components. The main source of income is from farming systems with grass production the predominant source of forage. For rangeland managers to utilise this source sustainably, the accurate determination of grazing capacity is vital since it allows for adapting the animal load, and therefore the grazing pressure, to the actual capacity of the land.  Various practical approaches and methodologies were investigated to update the existing Namibian grazing capacity map that was compiled more than three decades ago from the expert, but nonetheless subjective, opinion of farmers, extension officers and pasture scientists. The methodologies studied in this paper include the estimation of seasonal herbaceous biomass production using satellite imagery, land cover mapping and the quantitative yield method of determining available forage. It is expected that combining all these methods (information from remote sensing, adjusted with scientifically established coefficients for woody cover, accessibility and palatability and the incorporation of the clipping technique [quantitative yield method] as a ground truthing mechanism) will provide a tool to objectively establish rangeland productivity and thus grazing capacity in Namibia.

Keywords: agriculture; biomass; land cover; livestock; productivity; rangelands

African Journal of Range & Forage Science 2009, 26(3): 133–138