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Reduced transpiration response to precipitation pulses precedes mortality in a piñon–juniper woodland subject to prolonged drought
Author(s) -
Plaut Jennifer A.,
Wadsworth W. Duncan,
Pangle Robert,
Yepez Enrico A.,
McDowell Nate G.,
Pockman William T.
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12392
Subject(s) - transpiration , juniper , precipitation , environmental science , woodland , antecedent moisture , agronomy , antecedent (behavioral psychology) , biology , ecology , botany , geography , photosynthesis , runoff curve number , meteorology , surface runoff , psychology , developmental psychology
Summary Global climate change is predicted to alter the intensity and duration of droughts, but the effects of changing precipitation patterns on vegetation mortality are difficult to predict. Our objective was to determine whether prolonged drought or above‐average precipitation altered the capacity to respond to the individual precipitation pulses that drive productivity and survival. We analyzed 5 yr of data from a rainfall manipulation experiment in piñon–juniper ( P inus edulis – J uniperus monosperma ) woodland using mixed effects models of transpiration response to event size, antecedent soil moisture, and post‐event vapor pressure deficit. Replicated treatments included irrigation, drought, ambient control and infrastructure control. Mortality was highest under drought, and the reduced post‐pulse transpiration in the droughted trees that died was attributable to treatment effects beyond drier antecedent conditions and reduced event size. In particular, trees that died were nearly unresponsive to antecedent shallow soil moisture, suggesting reduced shallow absorbing root area. Irrigated trees showed an enhanced response to precipitation pulses. Prolonged drought initiates a downward spiral whereby trees are increasingly unable to utilize pulsed soil moisture. Thus, the additive effects of future, more frequent droughts may increase drought‐related mortality.