Interactions among hydro-aeolian processes and micro-geomorphology stimulate hot spots of sediment carbon source and sink within a coppice dune system

Abstract

ABSTRACT We evaluated the impacts of the interactions among hydro-aeolian processes and micro-geomorphology on mechanisms controlling the sediment carbon source and sink within a coppice dune. The sediment sampling process was performed within different positions of each dune. Sediment grain size distribution, geometric mean diameter, mean weight diameter, labile SOC, CO2 flux, and C mineralization ratio were measured. The finest sediments were observed on the dune edge. The labile SOC and CO2 flux rate showed an increasing trend in the edge, windward, and top positions. However, the C mineralization ratio decreased only in the dune edge. A significant increase of clay fractions at the dune edge can result from the horizontal sediment transport by runoff from the interdune area to the dune. The SOC could bond with clay fractions to contribute toward the formation of soil aggregation, causing less vulnerability of SOC to microbial respiration. A significant increase of sand fractions, transported by the aeolian process, on the top and windward positions could not protect SOC against decomposition. The interactions among hydro-aeolian processes and micro-geomorphology could encourage the hot spots of sediment carbon reservoirs within the dryland landforms that have a significant proportion in the exchange of carbon to the atmosphere.