Seasonal changes in the soil moisture distribution around bare rock outcrops within a karst rocky desertification area (Fuyuan County, Yunnan Province, China)

Abstract

The spatial and temporal soil moisture distribution is an important control on surface ecological processes in areas with rock outcrops resulting from karst rocky desertification (KRD). To explore the local effects of bare rocks within different seasons, soil moisture was measured in a KRD region (Fuyuan County, Yunnan Province, southwest China) at different depths and in different directions and distances from rock outcrops in both the dry and the wet seasons. The soil moisture north and east of the rocks was higher compared to the other directions and to the control plot. This effect is attributed to the shading by the rocks. The shading effect is evident in all seasons but more pronounced in the dry season. In the wet season, the directional dependency is restricted to the surface layer and the increase in soil moisture with depth is more pronounced around the rocks than at the control plot. This is attributed to precipitation-induced runoff from the rock outcrops infiltrating into the deeper layers at the rock–soil interface. These findings suggest the redistribution of water in the wet season and the spatial variation of evapotranspiration in the dry season are factors controlling the local soil moisture pattern around the rock outcrops.