Evaluating derived vegetation indices and cover fraction to estimate rangeland aboveground biomass in semi-arid environments

Abstract

This study was conducted to assess satellite data for quantifying and mapping the spatial distribution of rangeland biophysical parameters (aboveground biomass) from different geographic locations in the North West province, South Africa. Two major factors affecting the quality and conditions of the rangelands, namely rainfall zones and grazing intensities, were used to define sampling classes to represent the predominantly Savanah environment. Remote sensing vegetation indices (NDVI and SAVI) and vegetation cover fraction (SMA) were used to quantify the aboveground biomass using regression models of the sample aboveground biomass as a function. Results showed that private ranches in high rainfall areas yielded the highest aboveground biomass (159 kg 100 m(-2)) while the lowest biomass yield (10 kg 100 m(-2)) was obtained from the communal rangelands in the low rainfall area. The SAVI performed well (0.64) in the low rainfall areas but the coefficient of determination between the AGB and SAVI was not significant (at p