Surface control of desert pavement pedologic process and landscape function, Cima Volcanic field, Mojave Desert, California

Desert pavement is a distinctive feature widespread across arid lands of the world. It plays a dynamic role in geomorphic, hydrologic, and ecologic processes. Where desert pavement predominates, infiltration is limited and rainfall is delivered as runoff to nearby bare ground areas where shrubs cluster. Desert pavement surfaces may appear monotonously flat and barren, but we have found, instead, that they are a complex association of landscape and hydrologic elements governed by their surface characteristics. Previously, we identified six unique surface mosaic types that accurately capture the subtle, but distinct, variations in surface clast arrangements for a desert pavement landscape formed on a single-aged basalt flow in the Mojave Desert. We now report that these surface mosaics predict the spatial distribution of fundamental desert vegetation and soil characteristics. Characteristics of soil morphology and texture, the leaching depth of soluble salts, percent plant cover, and shrub species diversity are remarkably consistent for each mosaic type across a 580,000-year-old basalt flow even when measured >1 km apart. Hydrologic character is distinctly different between desert pavement and bare ground regions and vegetation distributions reflect the spatially heterogeneous soil moisture. Where desert shrubs cluster on the three bare ground surface mosaics, leaching is deep, removing most soluble salts to below the 50-cm depth. Where shrubs are absent or few, on the three desert pavement mosaics, leaching depths are shallow, with soluble salt depth distributions as well as desert shrub percent cover precisely controlled by the percent clast cover of the surface.