DOI: 10.5194/hess-23-2129-2019
论文题名: Unexplained hydrogen isotope offsets complicate the identification and quantification of tree water sources in a riparian forest
作者: Barbeta A. ; Jones S.P. ; Clavé L. ; Wingate L. ; Gimeno T.E. ; Fréjaville B. ; Wohl S. ; Ogee J.
刊名: Hydrology and Earth System Sciences
ISSN: 1027-5606
出版年: 2019
卷: 23, 期: 4 起始页码: 2129
结束页码: 2146
语种: 英语
Scopus关键词: Forestry
; Hydrogen
; Isotopes
; Mixing
; Mixtures
; Plants (botany)
; Sensitivity analysis
; Soil moisture
; Environmental conditions
; Isotope compositions
; Isotopic composition
; Isotopic fractionations
; Isotopic separation
; Relative contribution
; Soil fractionations
; Stable water isotopes
; Rivers
; deciduous tree
; environmental conditions
; growing season
; hydrogen isotope
; identification method
; isotopic composition
; isotopic fractionation
; quantitative analysis
; riparian forest
; shallow soil
; vadose zone
; France
; Fagus sylvatica
; Quercus robur
英文摘要: We investigated plant water sources of an emblematic refugial population of Fagus sylvatica (L.) in the Ciron river gorges in south-western France using stable water isotopes. It is generally assumed that no isotopic fractionation occurs during root water uptake, so that the isotopic composition of xylem water effectively reflects that of source water. However, this assumption has been called into question by recent studies that found that, at least at some dates during the growing season, plant water did not reflect any mixture of the potential water sources. In this context, highly resolved datasets covering a range of environmental conditions could shed light on possible plant soil fractionation processes responsible for this phenomenon. In this study, the hydrogen (2H) and oxygen (18O) isotope compositions of all potential tree water sources and xylem water were measured fortnightly over an entire growing season. Using a Bayesian isotope mixing model (MixSIAR), we then quantified the relative contribution of water sources for F. sylvatica and Quercus robur (L.) trees. Based on 18O data alone, both species used a mix of top and deep soil water over the season, with Q. robur using deeper soil water than F. sylvatica. The contribution of stream water appeared to be marginal despite the proximity of the trees to the stream, as already reported for other riparian forests. Xylem water 18O could always be interpreted as a mixture of deep and shallow soil waters, but the 2H of xylem water was often more depleted than the considered water sources. We argue that an isotopic fractionation in the unsaturated zone and/or within the plant tissues could underlie this unexpected relatively depleted 2H of xylem water, as already observed in halophytic and xerophytic species. By means of a sensitivity analysis, we found that the estimation of plant water sources using mixing models was strongly affected by this 2H depletion. A better understanding of what causes this isotopic separation between xylem and source water is urgently needed. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/162984
Appears in Collections: 气候变化与战略
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作者单位: Barbeta, A., INRA, UMR ISPA, Villenave d'Ornon, 33140, France; Jones, S.P., INRA, UMR ISPA, Villenave d'Ornon, 33140, France; Clavé, L., INRA, UMR ISPA, Villenave d'Ornon, 33140, France; Wingate, L., INRA, UMR ISPA, Villenave d'Ornon, 33140, France; Gimeno, T.E., INRA, UMR ISPA, Villenave d'Ornon, 33140, France, BC3 - Basque Centre for Climate Change - Klima Aldaketa Ikergai, Leioa, 48940, Spain, IKERBASQUE, Basque Foundation for Science, Bilbao, 48008, Spain; Fréjaville, B., INRA, UMR ISPA, Villenave d'Ornon, 33140, France; Wohl, S., INRA, UMR ISPA, Villenave d'Ornon, 33140, France; Ogee, J., INRA, UMR ISPA, Villenave d'Ornon, 33140, France
Recommended Citation:
Barbeta A.,Jones S.P.,Clavé L.,et al. Unexplained hydrogen isotope offsets complicate the identification and quantification of tree water sources in a riparian forest[J]. Hydrology and Earth System Sciences,2019-01-01,23(4)