Root grafts matter for inter-tree water exchange – a quantification of water translocation between root grafted mangrove trees using field data and model based indication

Wimmler, M.-C., Vovides, A. G. , Peters, R., Walther, M., Nadezhdina, N. and Berger, U. (2022) Root grafts matter for inter-tree water exchange – a quantification of water translocation between root grafted mangrove trees using field data and model based indication. Annals of Botany, 130(3), pp. 317-330. (doi: 10.1093/aob/mcac074) (PMID:35686514)

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Background and Aims: Trees interconnected through functional root grafts can exchange resources, but the effect of exchange on trees remains under debate. A mechanistic understanding of resources exchange via functional root grafts will help understand their ecological implications for tree water exchange for individual trees, groups of trees, and forest stands. Methods: To identify the main patterns qualitatively describing the movement of sap between grafted trees, we reviewed available literature on root grafting in woody plants that focus on tree allometry and resource translocation via root grafts. We then extended the BETTINA model, which simulates mangrove (Avicennia germinans) tree growth on the individual tree scale, in order to synthesize the available empirical information. Using allometric data from a field study in mangrove stands, we simulated potential water exchange and analyzed movement patterns between grafted trees. Key Results: In the simulations, relative water exchange ranged between -9.17 and 20.3 %, and was driven by gradients of water potential, i.e. differences in tree size and water availability. Moreover, the exchange of water through root grafts alters the water balance of trees and their feedback with the soil: grafted trees that receive water from their neighbors reduce their water uptake. Conclusions: Our individual-tree modelling study is a first theoretical attempt to quantify root graft-mediated water exchange between trees. Our findings indicate that functional root grafts represent a vector of hydraulic redistribution, helping to maintain the water balance of grafted trees. This non-invasive approach can serve as a fundament for designing empirical studies to better understand the role of grafted root interaction networks on a broader scale.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Vovides, Dr Alejandra
Authors: Wimmler, M.-C., Vovides, A. G., Peters, R., Walther, M., Nadezhdina, N., and Berger, U.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Annals of Botany
Publisher:Oxford University Press
ISSN (Online):1095-8290
Published Online:10 June 2022
Copyright Holders:Copyright © 2022 The Authors
First Published:First published in Annals of Botany 130(3): 317-330
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
301790MOnitoring Mangrove ExteNT & Services (MOMENTS): What is controlling Tipping Points?Thorsten BalkeNatural Environment Research Council (NERC)NE/P014127/1GES - Geography