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This content will become publicly available on December 14, 2018

Title: Manipulative experiments demonstrate how long-term soil moisture changes alter controls of plant water use

Tree transpiration depends on biotic and abiotic factors that might change in the future, including precipitation and soil moisture status. Although short-term sap flux responses to soil moisture and evaporative demand have been the subject of attention before, the relative sensitivity of sap flux to these two factors under long-term changes in soil moisture conditions has rarely been determined experimentally. We tested how long-term artificial change in soil moisture affects the sensitivity of tree-level sap flux to daily atmospheric vapor pressure deficit ( VPD) and soil moisture variations, and the generality of these effects across forest types and environments using four manipulative sites in mature forests. Exposure to relatively long-term (two to six years) soil moisture reduction decreases tree sap flux sensitivity to daily VPD and relative extractable water ( REW) variations, leading to lower sap flux even under high soil moisture and optimal VPD. Inversely, trees subjected to long-term irrigation showed a significant increase in their sensitivity to daily VPD and REW, but only at the most water-limited site. The ratio between the relative change in soil moisture manipulation and the relative change in sap flux sensitivity to VPD and REW variations was similar across sites suggesting common adjustmentmore » mechanisms to long-term soil moisture status across environments for evergreen tree species. Altogether, our results show that long-term changes in soil water availability, and subsequent adjustments to these novel conditions, could play a critical and increasingly important role in controlling forest water use in the future.« less
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [5] ;  [6] ;  [7] ;  [8]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. CNRS, Montpellier Cedex (France)
  3. Australian National Univ., Canberra, ACT (Australia); Univ. of Edinburgh, Edinburgh (United Kingdom)
  4. ICREA, Barcelona (Spain); CREAF, Barcelona (Spain)
  5. Univ. of New Mexico, Albuquerque, NM (United States)
  6. Univ. of Edinburgh, Edinburgh (United Kingdom); Univ. of Helsinki, Helsinki (Finland)
  7. Swiss Federal Institute for Forest, Birmensdorf (Switzerland)
  8. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0098-8472
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Environmental and Experimental Botany
Additional Journal Information:
Journal Name: Environmental and Experimental Botany; Journal ID: ISSN 0098-8472
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; 60 APPLIED LIFE SCIENCES; acclimation; climate change; drought; irrigation; sap flux; vapor pressure deficit; water use
OSTI Identifier: