The Effect of Shelter on the Temperature and Moisture of Desert Sands

Abstract

Mechanical shelters, including both covering sand binders and standing windbreaks, are found to be significant not only in reducing wind speed in the surface layer and thus lessening sand drifting, but also in reducing sand temperatures and preserving moisture for optimal plant growth. Shelters are shown to reduce sand temperatures in the midday hours (at a depth of 0.15 m) by 1.5–2.5°C on slopes of southern exposure and by as much as 5.5° on north-facing slopes of sand dunes. The difference in sand-surface temperatures on the windward and lee sides of barriers is found to reach 5° on south-facing slopes and 10° on north-facing slopes. Both covering sand binders and standing windbreaks also tend to reduce evaporation from the sand surface. Stabilized sand dunes are shown to retain 60 percent more moisture on the average than unprotected dunes. Contrary to some statements in the literature, standing windbreaks are found not to produce desiccation of the sand. The reduction of the sand temperature on the shady side of barriers combined with the increase in sand moisture suggest optimal places for plant growth: These are the lee side on south-facing slopes and the windward side on north-facing slopes of sand dunes.