气候变化领域集成服务门户(CCPortal): Unexplained hydrogen isotope offsets complicate the identification and quantification of tree water sources in a riparian forest

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DOI	10.5194/hess-23-2129-2019
	Unexplained hydrogen isotope offsets complicate the identification and quantification of tree water sources in a riparian forest
	Barbeta A.; Jones S.P.; Clavé L.; Wingate L.; Gimeno T.E.; Fréjaville B.; Wohl S.; Ogee J.
发表日期	2019
ISSN	1027-5606
起始页码	2129
结束页码	2146
卷号	23 期号:4
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.
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
来源期刊	Hydrology and Earth System Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/159694
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
推荐引用方式 GB/T 7714	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],2019,23(4).
APA	Barbeta A..,Jones S.P..,Clavé L..,Wingate L..,Gimeno T.E..,...&Ogee J..(2019).Unexplained hydrogen isotope offsets complicate the identification and quantification of tree water sources in a riparian forest.Hydrology and Earth System Sciences,23(4).
MLA	Barbeta A.,et al."Unexplained hydrogen isotope offsets complicate the identification and quantification of tree water sources in a riparian forest".Hydrology and Earth System Sciences 23.4(2019).