Co‐occurring woody species have diverse hydraulic strategies and mortality rates during an extreme drought |
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| Authors: | Daniel M. Johnson Jean‐Christophe Domec Z. Carter Berry Amanda M. Schwantes Katherine A. McCulloh David R. Woodruff H. Wayne Polley Remí Wortemann Jennifer J. Swenson D. Scott Mackay Nate G. McDowell Robert B. Jackson |
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| Affiliation: | 1. College of Natural Resources, University of Idaho, Moscow, ID, USA;2. Bordeaux Sciences Agro, UMR INRA‐ISPA 1391, Gradignan, France;3. Nicholas School of the Environment, Duke University, Durham, NC, USA;4. Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, USA;5. Department of Botany, University of Wisconsin‐Madison, Madison, WI, USA;6. US Forest Service, Pacific Northwest Research Station, Corvallis, OR, USA;7. Grassland, Soil & Water Research Laboratory USDA–Agricultural Research Service, Temple, TX, USA;8. INRA Nancy, UMR INRA‐UL 1137 Ecologie et Ecophysiologie Forestières, Champenoux, France;9. Department of Geography, State University of New York, Buffalo, NY, USA;10. Pacific Northwest National Laboratory, Richland, WA, USA;11. Department of Earth System Science, Woods Institute for the Environment, and Precourt Institute for Energy, Stanford University, Stanford, CA, USA |
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| Abstract: | From 2011 to 2013, Texas experienced its worst drought in recorded history. This event provided a unique natural experiment to assess species‐specific responses to extreme drought and mortality of four co‐occurring woody species: Quercus fusiformis, Diospyros texana, Prosopis glandulosa, and Juniperus ashei. We examined hypothesized mechanisms that could promote these species' diverse mortality patterns using postdrought measurements on surviving trees coupled to retrospective process modelling. The species exhibited a wide range of gas exchange responses, hydraulic strategies, and mortality rates. Multiple proposed indices of mortality mechanisms were inconsistent with the observed mortality patterns across species, including measures of the degree of iso/anisohydry, photosynthesis, carbohydrate depletion, and hydraulic safety margins. Large losses of spring and summer whole‐tree conductance (driven by belowground losses of conductance) and shallower rooting depths were associated with species that exhibited greater mortality. Based on this retrospective analysis, we suggest that species more vulnerable to drought were more likely to have succumbed to hydraulic failure belowground. |
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| Keywords: | carbon gain cavitation climate change stomatal conductance water relations |
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