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Transpiration by desert phreatophytes is poorly understood, and the few existing data are difficult to extrapolate spatially. This study developed transpiration coefficients (Kc) for Atriplex lentiformis ssp. torreyi, Chrysothamnus nauseosus and Sarcobatus vermiculatus to estimate transpiration using vegetation cover measurements. The Kc were developed from stomatal conductance, reference evapotranspiration (ETr), and modeled leaf area index (LAI). Transpiration estimates using the Kc generally agree with values reported in the literature, but few examples of simultaneous leaf area and independent transpiration measurements exist to rigorously test this approach. A study has been initiated in the Owens Valley of California to make this necessary comparison. (C) 2001 Academic Press.