Delineation of Soil Parameters to assess Ecosystem Degradation using Spectral Mixture Analysis

Abstract

Land degradation processes in the subtropical Thicket Biome in the Eastern Cape Province, South Africa, are observed and monitored. As a result, a significant loss of soil quality on such sites has been recorded. This study focuses on the determination of fundamental soil parameters like organic carbon, iron, and clay in order to assess ecosystem degradation. The test site in South Africa is surveyed for ground truth and hyperspectral image data are obtained. We take advantage of spectral mixture analysis to approximate the ‘pure’ soil signal from mixing pixel signatures. For a subsequent quantification of soil parameters, spectral feature analysis is linked with multiple linear regression techniques. For organic carbon and iron, calibrations of high accuracy are used for the prediction of image data. The results highly correlate with measured contents. In contrast, the quantification of clay content is still problematic mostly due to the existence of soil structural crusts.