Distribution of vegetation in wind-dominated landscapes: Implications for wind erosion modeling and landscape processes

Dust emission and wind erosion from arid and semiarid environments provide a major source of global atmospheric aerosols. Well-known relations between wind stress and saltation sand flux for sand sheets and relations between sand flux and dust emission by sandblasting have enabled construction of du st models that have only been partly successful in predicting atmospheric m ineral dust concentrations. Most models of wind erosion assume that vegetat ion is evenly distributed. Through the use of field, Fourier transform, and semivariogram analysis, we show that mesquite dunelands in the Chihuahuan Desert of southern New Mexico, United States, have anisotropic shrub distri butions. Elongated areas of bare soil, "streets," which are aligned with th e prevailing winds may partially explain discrepancies between observed and predicted atmospheric dust concentrations. Soils in the streets are not pr otected from winds blowing down the streets and may therefore produce more dust than if vegetation were more evenly distributed. Currently, few desert landscape evolution models take the rule of wind explicitly into account. The existence of streets implies that wind plays a major role in the evolut ion of vegetated arid and semiarid landscapes with wind-erodible soils. Her e wind acts in tandem with water to enforce islands of fertility centered a round individual shrubs and may provide an explanation for reduced soil fer tility observed in shrublands. Furthermore, in order for mathematical model s of dust flux to be successful in these landscapes, new landscape models a re required which incorporate the existence and orientation of streets.