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Hydraulic acclimation in a Mediterranean oak subjected to permanent throughfall exclusion results in increased stem hydraulic capacitance
Author(s) -
Salomón Roberto L.,
Steppe Kathy,
Ourcival Jean M.,
Villers Selwyn,
RodríguezCalcerrada Jesús,
Schapman Roderick,
Limousin Jean M.
Publication year - 2020
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.13751
Subject(s) - throughfall , acclimatization , environmental science , mediterranean climate , water content , canopy , scots pine , water potential , hardwood , horticulture , botany , chemistry , biology , ecology , soil water , soil science , pinus <genus> , geotechnical engineering , engineering
Abstract Stem water storage capacity and hydraulic capacitance (C S ) play a crucial role in tree survival under drought‐stress. To investigate whether C S adjusts to increasing water deficit, variation in stem water content (StWC) was monitored in vivo for 2 years and related to periodical measurements of tree water potential in Mediterranean Quercus ilex trees subjected either to permanent throughfall exclusion (TE) or to control conditions. Seasonal reductions in StWC were larger in TE trees relative to control ones, resulting in greater seasonal C S (154 and 80 kg m −3 MPa −1 , respectively), but only during the first phase of the desorption curve, when predawn water potential was above −1.1 MPa. Below this point, C S decreased substantially and did not differ between treatments (<20 kg m −3 MPa −1 ). The allometric relationship between tree diameter and sapwood area, measured via electrical resistivity tomography, was not affected by TE. Our results suggest that (a) C S response to water deficit in the drought‐tolerant Q. ilex might be more important to optimize carbon gain during well‐hydrated periods than to prevent drought‐induced embolism formation during severe drought stress, and (b) enhanced C S during early summer does not result from proportional increases in sapwood volume, but mostly from increased elastic water.