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Title: Native versus non-native tree competition for water resources along an intermittent reach of the San Pedro River, Arizona 1935

Author
item McGuire, Roberta
item Scott, Russell - Russ
item GLENN, E. - UNIVERSITY OF ARIZONA
item Moran, Mary

Submitted to: Water Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/27/2007
Publication Date: 8/29/2007
Citation: Mcguire, R.R., Scott, R.L., Glenn, E.P., Moran, M.S. 2007. Native versus non-native tree competition for water resources along an intermittent reach of the San Pedro River, Arizona. 2007 Regional Water Symposium, 29 Aug. - 1 Sept., Tucson, AZ. {abstract}.

Interpretive Summary: Many transpiration studies on salt cedar (Tamarix ramosissima) have indicated that its water use is considerably greater than native trees; however these results have varied on temporal and spatial scales making it difficult to draw firm conclusions, especially in co-occurring communities. Using sap flow techniques, we quantified transpiration in co-occurring communities of native cottonwood (Populus fremontii) and Arizona ash (Fraxinus velutina) trees and invasive salt cedar during the dry and hot pre-monsoon season along an intermittent reach of the San Pedro River in southeastern Arizona. We also monitored meteorological variables and the declining groundwater levels to better understand their competition for water and the plant physiological response to environmental stressors. Riparian restoration efforts aimed at "water salvage" have focused on salt cedar removal to encourage return of native riparian forests. There is need to define environments and conditions in which salt cedar removal is unnecessary as its water use may not be significant.

Technical Abstract: Many transpiration studies on salt cedar (Tamarix ramosissima) have indicated that its water use is considerably greater than native trees; however these results have varied on temporal and spatial scales making it difficult to draw firm conclusions, especially in co-occurring communities. Using sap flow techniques, we quantified transpiration in co-occurring communities of native cottonwood (Populus fremontii) and Arizona ash (Fraxinus velutina) trees and invasive salt cedar during the dry and hot pre-monsoon season along an intermittent reach of the San Pedro River in southeastern Arizona. We also monitored meteorological variables and the declining groundwater levels to better understand their competition for water and the plant physiological response to environmental stressors. Riparian restoration efforts aimed at "water salvage" have focused on salt cedar removal to encourage return of native riparian forests. There is need to define environments and conditions in which salt cedar removal is unnecessary as its water use may not be significant.