Effects of coppice dune topography and vegetation on soil water dynamics in a cold-desert ecosystem

The relationships of soil water dynamics to arid-land coppice dune/swale topography and associated plants were examined under normal and enhanced precipitation. Three conditions were compared: coppice dunes dominated by Grayia spinosa, sparsely vegetated swales, and swales dominated by Artemisia tridentata. Sparsely vegetated swales were wetter than G. spinosa coppice dunes or A. tridentata swales. The effect of enhanced precipitation on end-of-season soil water storage and profile patterns was negligible. Soil water storage was negatively correlated with the number and size of nearby plants. Root biomass was highest near the surface and decreased with depth down to 2 m. The root biomass under G. spinosa coppice dunes was 10 times greater than in sparsely vegetated swales or swales dominated by A. tridentata. Variability in soil water characteristics was more strongly associated with vegetation patterns than with topography. The swales dominated by A. tridentata were significantly drier than sparsely vegetated swales. This ecosystem can recycle at least two times normal precipitation to the atmosphere via evapotranspiration.