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Tree Mortality Decreases Water Availability and Ecosystem Resilience to Drought in Piñon-Juniper Woodlands in the Southwestern U.S.
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Final Published Version
Author
Morillas, L.Pangle, R. E.
Maurer, G. E.
Pockman, W. T.
McDowell, N.
Huang, C.-W.
Krofcheck, D. J.
Fox, Andrew
Sinsabaugh, R. L.
Rahn, T. A.
Litvak, M. E.
Affiliation
Univ Arizona, Sch Nat Resources & EnvironmIssue Date
2017-12
Metadata
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AMER GEOPHYSICAL UNIONCitation
Tree Mortality Decreases Water Availability and Ecosystem Resilience to Drought in Piñon-Juniper Woodlands in the Southwestern U.S. 2017, 122 (12):3343 Journal of Geophysical Research: BiogeosciencesRights
© 2017. American Geophysical Union. All Rights Reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Climate-driven tree mortality has increased globally in response to warmer temperature and more severe drought. To examine how tree mortality in semiarid biomes impacts surface water balance, we experimentally manipulated a pinon-juniper (PJ) woodland by girdling all adult pinon trees in a 4 ha area, decreasing pinon basal area by similar to 65%. Over 3.5 years (2009-2013), we compared water flux measurements from this girdled site with those from a nearby intact PJ woodland. Before and after girdling, the ratio of evapotranspiration (ET) to incoming precipitation was similar between the two sites. Girdling altered the partitioning of ET such that the contribution of canopy transpiration to ET decreased 9-14% over the study period, relative to the intact control, while noncanopy ET increased. We attributed the elevated noncanopy ET in the girdled site each year to winter increases in sublimation and summer increases in both soil evaporation and below-canopy transpiration. Although we expected that mortality of a canopy dominant would increase the availability of water and other resources to surviving vegetation, we observed a decrease in both soil volumetric water content and sap flow rates in the remaining trees at the girdled site, relative to the control. This postgirdling decrease in the performance of the remaining trees occurred during the severe 2011-2012 drought, suggesting that pinon mortality may trigger feedback mechanisms that leave PJ woodlands drier relative to undisturbed sites and potentially more vulnerable to drought.Note
6 month embargo; published online: 29 December 2017ISSN
21698953Version
Final published versionSponsors
DOE Office of Science TES [SC DE-SC0008088]; NSF Ecosystems [NSF-DEB-1557176]; Pacific Northwest National Lab's LDRD program; Los Alamos National Lab; College of Arts and Sciences at the University of New MexicoAdditional Links
http://doi.wiley.com/10.1002/2017JG004095ae974a485f413a2113503eed53cd6c53
10.1002/2017JG004095