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ARS Home » Pacific West Area » Boise, Idaho » Northwest Watershed Research Center » Research » Publications at this Location » Publication #65577


item Hanson, Clayton

Submitted to: International Rangeland Congress
Publication Type: Proceedings
Publication Acceptance Date: 7/24/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Evapotranspiration is the second largest component of the water balance in arid and semiarid rangeland ecosystems and often accounts for nearly all of the precipitation. An understanding of the evapotranspiration process is important to the study of plant dynamics and hydrological processes within these ecosystems. Currently, there is very little daily evapotranspiration data available for rangelands. This study used a Bowen ratio-energy balance system to measure daily evapotranspiration fluxes over several sagebrush-grass communities within a shrub-dominated watershed in southwest Idaho. Results of this study showed that there was considerable variation in the evapotranspiration dynamics and utilization of solar energy for evapotranspiration among sagebrush-grass communities within the same watershed. Maximum daily evapotranspiration fluxes varied from about 4mm per day on a dry, low sagebrush (Artemisia arbuscula) site of over 6mm per day on a somewhat wetter big sagebrush (A. tridentata vaseyana) site. With water nonlimiting for plant growth, the low sagebrush and big sagebrush sites used 70 and 100 percent, respectively, of the available solar energy for evapotranspiration.

Technical Abstract: ABSTRACT Daily and seasonal evapotranspiration (ET) fluxes were measured over several plant communities within a shrub-dominated watershed in southwest Idaho, USA using a Bowen ratio-energy balance system. Maximum daily ET fluxes varied from less than 4.0mm per day from a dry low sagebrush (Artemisia arbuscula) site to over 6mm per day from the wetter big sagebrush (A. tridentata vaseyana) site. Maximum monthly ET/potential ET ratios varied from about 0.7 on the driest sites to over 1.0 on the wettest site.