McAuliffe, J.R. 2003. The interface between precipitation and vegetation: The importance of soils in arid and semiarid environments. Pp. 9-27 in Changing precipitation regimes & terrestrial ecosystems: A North American perspectve. Weltzin, J.F. & McPherson,G.R. (eds). University of Arizona Press, Tucson.

This chapter examines how soils mediate the ecological effects of precipitation in arid and semiarid environments by controlling the spatial and temporal distribution of plant-available soil moisture. It emphasizes three critical dimensions of soil moisture: depth of infiltration, horizontal heterogeneity, and temporal persistence. Variations in soil texture, horizon development, lithology, and geomorphic setting create contrasting hydrologic environments that favor different plant functional strategies, ranging from shallow-rooted, intensive exploiters of episodic rainfall to deep-rooted woody plants that access persistent subsurface moisture. Through examples from grasslands, deserts, and chaparral of the American Southwest, the chapter shows that soil properties largely determine vegetation composition, ecosystem responses to disturbance, and susceptibility to woody plant encroachment. It argues that realistic predictions of vegetation change under climate change and land use must explicitly incorporate soil hydrology and geomorphic context.