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Causes and consequences of pronounced variation in the isotope composition of plant xylem water

De Deurwaerder, Hannes P. T. and Visser, Marco D. and Detto, Matteo and Boeckx, Pascal and Meunier, Felicien and Kuehnhammer, Kathrin and Magh, Ruth and Marshall, John D and Wang, Lixin and Zhao, Liangju and Verbeeck, Hans (2020). Causes and consequences of pronounced variation in the isotope composition of plant xylem water. Biogeosciences. 17 , 4853-4870
[Journal article]

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Abstract

Stable isotopologues of water are widely used to derive relative root water uptake (RWU) profiles and average RWU depth in lignified plants. Uniform isotope composition of plant xylem water (delta(xyl)) along the stem length of woody plants is a central assumption of the isotope tracing approach which has never been properly evaluated.Here we evaluate whether strong variation in delta(xyl) within woody plants exists using empirical field observations from French Guiana, northwestern China, and Germany. In addition, supported by a mechanistic plant hydraulic model, we test hypotheses on how variation in delta(xyl) can develop through the effects of diurnal variation in RWU, sap flux density, diffusion, and various other soil and plant parameters on the delta(xyl) of woody plants.The hydrogen and oxygen isotope composition of plant xylem water shows strong temporal (i.e., sub-daily) and spatial (i.e., along the stem) variation ranging up to 25.2 parts per thousand and 6.8 parts per thousand for delta H-2 and delta O-18, respectively, greatly exceeding the measurement error range in all evaluated datasets. Model explorations predict that significant delta(xyl) variation could arise from diurnal RWU fluctuations and vertical soil water heterogeneity. Moreover, significant differences in delta(xyl) emerge between individuals that differ only in sap flux densities or are monitored at different times or heights.This work shows a complex pattern of delta(xyl) transport in the soil-root-xylem system which can be related to the dynamics of RWU by plants. These dynamics complicate the assessment of RWU when using stable water isotopologues but also open new opportunities to study drought responses to environmental drivers. We propose including the monitoring of sap flow and soil matric potential for more robust estimates of average RWU depth and expansion of attainable insights in plant drought strategies and responses.

Authors/Creators:De Deurwaerder, Hannes P. T. and Visser, Marco D. and Detto, Matteo and Boeckx, Pascal and Meunier, Felicien and Kuehnhammer, Kathrin and Magh, Ruth and Marshall, John D and Wang, Lixin and Zhao, Liangju and Verbeeck, Hans
Title:Causes and consequences of pronounced variation in the isotope composition of plant xylem water
Year of publishing :2020
Volume:17
Page range:4853-4870
Number of Pages:18
Publisher:COPERNICUS GESELLSCHAFT MBH
ISSN:1726-4170
Language:English
Publication Type:Journal article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
URN:NBN:urn:nbn:se:slu:epsilon-p-108702
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-108702
Additional ID:
Type of IDID
DOI10.5194/bg-17-4853-2020
Web of Science (WoS)000580917900001
ID Code:18699
Faculty:S - Faculty of Forest Sciences
Department:(S) > Dept. of Forest Ecology and Management
Deposited By: SLUpub Connector
Deposited On:19 Nov 2020 13:03
Metadata Last Modified:19 Nov 2020 13:11

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