Preprints
https://doi.org/10.5194/hess-2019-528
https://doi.org/10.5194/hess-2019-528
21 Oct 2019
 | 21 Oct 2019
Status: this preprint has been withdrawn by the authors.

How plant water status drives tree source water partitioning

Magali F. Nehemy, Paolo Benettin, Mitra Asadollahi, Dyan Pratt, Andrea Rinaldo, and Jeffrey J. McDonnell

Abstract. The stable isotopes of oxygen and hydrogen (δ2H and δ18O) have been widely used to investigate plant water source partitioning. These tracers have shed new light on patterns of plant water use in time and space. However, this black box approach has limited our source water interpretations and mechanistic understanding. Here, we combine measurements of stable isotope composition in xylem and soil water pools with measurements of plant hydraulics, fine root distribution and soil matric potential to investigate mechanism(s) driving tree water source partitioning. We used a 2 m3 lysimeter planted with a small willow tree (Salix viminalis) to conduct a high spatial-temporal resolution experiment. We found that tree water source partitioning was driven mainly by tree water status and not by patterns of fine root distribution. Source water partitioning was regulated by plant hydraulic response to changing atmospheric demand and soil matric potential. The depth distribution of soil matric potential appeared to be the largest control on the patterns of soil water partitioning during periods of tree water deficit. Contrary to the common steady state assumption in ecohydrological source water investigations, our results show that tree water use is a dynamic process, driven by tree water deficit. Overall, our findings suggest new research foci for future plant water isotopic investigations, highlighting the importance of hydrometric measurements from the plant perspective.

This preprint has been withdrawn.

Magali F. Nehemy, Paolo Benettin, Mitra Asadollahi, Dyan Pratt, Andrea Rinaldo, and Jeffrey J. McDonnell

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Magali F. Nehemy, Paolo Benettin, Mitra Asadollahi, Dyan Pratt, Andrea Rinaldo, and Jeffrey J. McDonnell
Magali F. Nehemy, Paolo Benettin, Mitra Asadollahi, Dyan Pratt, Andrea Rinaldo, and Jeffrey J. McDonnell

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This preprint has been withdrawn.