Spatial patterns of topsoil organic carbon in semi-arid areas - examples from SE Spain and Israel

The aim of the study carried out in Spain is to characterize spatial patterns of SOC in a Mediterranean, semi-arid area at different spatial scales and to assess the relationship between these patterns and terrain. We adopt a remote sensing based approach for the estimation of SOC in the topsoil. A statistical modeling approach is used to obtain quantitative, spatial estimates of SOC concentrations based on visible and near-infrared spectral properties of soils. Spatially distributed estimates (resolution 6 m) of SOC are obtained from the transfer of the statistical model to airborne hyperspectral data (HyMAP). Geostatistical techniques and digital elevation model analysis are used to characterize spatial patterns of SOC. A similar approach was adopted in the Negev, Israel, to derive spatial information on SOC distribution. Here, we focused on small scale variability of SOC and their relation to vegetation patterns and terrain. The results indicate that the semi-arid hydrological and geomorphological process domain in both study areas exerts strong control on the lateral distribution of SOC generating high, small scale variability but also spatially contiguous patterns at larger scales. We conclude that hyperspectral remote sensing can be successfully applied to quantify the spatial distribution of SOC and provide a methodological framework for the analysis of the data.