Nebkha dunes in the Molopo Basin, South Africa and Botswana: formation controls and their validity as indicators of soil degradation

Abstract

Nebkha dunes have been proposed as a reliable rapid indicator of aeolian erosion and dryland degradation. This paper tests the applicability of these links for the Molopo Basin, southern Africa where it is shown that nebkha sediments are largely locally derived from interdune areas and are significantly enriched in available inorganic nutrients. Feedbacks with the bush canopy are the most likely cause of the enrichment, such that this can occur without associated declines in nutrient availability in surrounding source areas. Thus, although the nebkhas indicate aeolian transport of sediment, the immediate association with soil degradation is over-simplistic.