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Quantifying transpirable soil water and its relations to tree water use dynamics in a water‐limited pine forest
Author(s) -
Klein Tamir,
Rotenberg Eyal,
CohenHilaleh Ella,
RazYaseef Naama,
Tatarinov Fyodor,
Preisler Yakir,
Ogée Jérôme,
Cohen Shabtai,
Yakir Dan
Publication year - 2014
Publication title -
ecohydrology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.982
H-Index - 54
eISSN - 1936-0592
pISSN - 1936-0584
DOI - 10.1002/eco.1360
Subject(s) - environmental science , soil water , water content , transpiration , infiltration (hvac) , growing season , hydrology (agriculture) , arid , water use , water flow , dry season , soil science , agronomy , ecology , geology , chemistry , geography , photosynthesis , biochemistry , geotechnical engineering , meteorology , biology
Knowledge of the relationship between soil water dynamics and tree water use is critical to understanding forest response to environmental change in water‐limited ecosystems. However, the dynamics in soil water availability for tree transpiration ( T t ) cannot be easily deduced from conventional measurements of soil water content (SWC), notably because T t is influenced by soil water potential (Ψ s ) that, in turn, depends on soil characteristics. Using tree sap flow and water potential and deriving depth‐dependent soil water retention curves, we quantified the ‘transpirable soil water content’ (tSWC) and its seasonal and inter‐annual variations in a semi‐arid Pinus halepensis forest. The results indicated that tSWC varied in time and with soil depth. Over one growing season T t was 57% of rain and 72% of the infiltrated SWC. In early winter, T t was exclusively supported by soil moisture at the top 10 cm (tSWC = 11 mm), whereas in spring (tSWC > 18 mm) and throughout the dry season, source water for T t shifted to 20–40 cm, where the maximum fine root density occurs. Simulation with the soil–plant–atmosphere water and energy transport model MuSICA supported the idea that consistent tSWC at the 20–40 cm soil layer critically depended on limited water infiltration below 40 cm, because of high water retention below this depth. Quantifying tSWC is critical to the precise estimation of the onset and termination of the growing season (when tSWC > 0) in this semi‐arid ecosystem. Copyright © 2013 John Wiley & Sons, Ltd.