Wide-Area Estimates of Stand Structure and Water Use of Tamarix spp. on the Lower Colorado River: Implications for Restoration and Water Management Projects |
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Authors: | Pamela L Nagler Edward P Glenn Kamel Didan John Osterberg Fiona Jordan Jack Cunningham |
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Institution: | U.S. Geological Survey, Southwest Biological Science Center, Sonoran Desert Research Station, BioSciences East Building, Room 125, University of Arizona, Tucson, AZ 85721, U.S.A.; Environmental Research Laboratory, University of Arizona, Tucson, AZ 85706, U.S.A.; Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721, U.S.A.; U.S. Bureau of Reclamation, Denver Federal Center, Denver CO 80225, U.S.A. |
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Abstract: | Tamarix spp. removal has been proposed to salvage water and allow native vegetation to recolonize western U.S. riparian corridors. We conducted wide‐area studies on the Lower Colorado River to answer some of the scientific questions about Tamarix water use and the consequences of removal, combining ground surveys with remote sensing methods. Tamarix stands had moderate rates of evapotranspiration (ET), based on remote sensing estimates, averaging 1.1 m/yr, similar to rates determined for other locations on the river and other rivers. Leaf area index values were also moderate, and stands were relatively open, with areas of bare soil interspersed within stands. At three Tamarix sites in the Cibola National Wildlife Refuge, groundwater salinity at the site nearest to the river (200 m) was relatively low (circa 2,250 mg/L) and was within 3 m of the surface. However, 750 and 1,500 m from the river, the groundwater salinity was 5,000–10,000 mg/L due to removal of water by the Tamarix stands. Despite the high groundwater salinity, the sites away from the river did not have saline surface soils. Only 1% of the mean annual river flow is lost to Tamarix ET on the Lower Colorado River in the United States, and the opportunities for water salvage through Tamarix removal are constrained by its modest ET rates. A possible alternative to Tamarix removal is to intersperse native plants among the stands to improve the habitat value of the riparian zone. |
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Keywords: | Populus Prosopis revegetation riparian Salix Tamarix water salvage |
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