Nonresponse of native Cottonwood trees to water additions during summer drought

Cox, Greg and Fischer, Dylan and Hart, Stephen C. and Whitham, T. G. (2005) Nonresponse of native Cottonwood trees to water additions during summer drought. Western North American Naturalist, 65 (2). pp. 175-185. ISSN 1527-0904

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Abstract

Studies have demonstrated that some riparian trees may switch their reliance on surface soil water (unsaturated or vadose zone) to groundwater (saturated zone) sources during the growing season in association with changes in moisture availability. A closely related question is: How do these trees respond to pulse increases in water availability in previously dry zones? We tested the whole-tree physiological response of 6 natural Populus genotypes to water additions during the peak of summer drought in northern Utah, USA. We found clear evidence that trees were insensitive to water additions to the surface soil that were twice the magnitude of whole-tree transpiration rates. Our results suggest that some cottonwoods may have little immediate transpiration of leaf conductance response to pulse soil moisture increases. This lack of response may be related to water-use strategy associated with regional climate patterns (i.e. genetic or environmental programming), cavitation recovery, or other physical determinants of water use such as depth to groundwater. Our data suggest that it is important to consider potential nonresponsiveness to changes in soil water availability when evaluating the impact of climate change on these important and productive ecosystems.

Item Type:	Article
Keywords:	sap flow, drought, cottonwood, water addition, conductance, water potential, Populus
Subjects:	Q Science > QK Botany
NAU Depositing Author Academic Status:	Faculty/Staff
Department/Unit:	College of Engineering, Forestry, and Natural Science > Biological Sciences
Date Deposited:	01 May 2017 20:20
URI:	http://openknowledge.nau.edu/id/eprint/2634

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