Tree water dynamics in a drying and warming world |
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| Authors: | Charlotte Grossiord Sanna Sevanto Isaac Borrego Allison M Chan Adam D Collins Lee T Dickman Patrick J Hudson Natalie McBranch Sean T Michaletz William T Pockman Max Ryan Alberto Vilagrosa Nate G McDowell |
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| Institution: | 1. Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA;2. Department of Biology, MSC03 202, University of New Mexico, Albuquerque, NM, USA;3. Fundación CEAM, Joint Research Unit University of Alicante – CEAM, Univ. Alicante, Alicante, Spain;4. Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA |
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| Abstract: | Disentangling the relative impacts of precipitation reduction and vapour pressure deficit (VPD) on plant water dynamics and determining whether acclimation may influence these patterns in the future is an important challenge. Here, we report sap flux density (FD), stomatal conductance (Gs), hydraulic conductivity (KL) and xylem anatomy in piñon pine (Pinus edulis) and juniper (Juniperus monosperma) trees subjected to five years of precipitation reduction, atmospheric warming (elevated VPD) and their combined effects. No acclimation occurred under precipitation reduction: lower Gs and FD were found for both species compared to ambient conditions. Warming reduced the sensibility of stomata to VPD for both species but resulted in the maintenance of Gs and FD to ambient levels only for piñon. For juniper, reduced soil moisture under warming negated benefits of stomatal adjustments and resulted in reduced FD, Gs and KL. Although reduced stomatal sensitivity to VPD also occurred under combined stresses, reductions in Gs, FD and KL took place to similar levels as under single stresses for both species. Our results show that stomatal conductance adjustments to high VPD could minimize but not entirely prevent additive effects of warming and drying on water use and carbon acquisition of trees in semi‐arid regions. |
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| Keywords: | acclimation hydraulics Juniperus monosperma megadrought Pinus edulis sap flux stomatal conductance transpiration vapour pressure deficit xylem anatomy |
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