Osmotic and Hydraulic Dynamics of Trees Under Water Deficit

Forests are facing increasing intensity and frequency of drought occurrences, making them more vulnerable to drought induced mortality. Understanding different plant traits which extend the time to drought induced mortality is crucial to identifying which species may be more resistant to water deficit under future climate scenarios. However, the interactions of mechanisms that cause a variability of water status in response to soil drying in different species is complex and poorly characterized. Specifically, there is a gap in knowledge in the interaction between stem water potential, with osmotic adjustment, hydraulic conductance and capacitance in different plant parts overtime in response to soil water content. In response to this knowledge gap, this project aims to: 1) Monitor the osmotic responses to water limitation in the roots, xylem, and leaves of various woody perennial species. 2) Characterize plant hydraulic conductance and capacitance responses to water deficit on a daily and seasonal scale. 3) Describe changes in root anatomy and in the localization of osmolytes within root tissues in response to changing water availability, and estimate their impact on shoot water supply. To achieve these aims we will monitor the hydraulic and osmotic responses to water deficit in various Quercus spp. (oak) and Fraxinus spp. (ash) as well as in Fagus sylvatica (beech) across Belgium and France (Figure 1). Additionally, as the hydraulic traits of conductance and capacitance are not easily measurable, we will use inverse modeling, using data collected from field measurements to predict daily fluctuations in hydraulic conductance seasonally. By achieving these aims, this project will provide greater insight into the interactions of different traits and mechanisms of various woody plant species to cope with water limitation. Furthermore, the vulnerability of different species to hydraulic failure can be better assessed to inform future forestry management practices. This project, overall, aims to address key mechanistic questions which will have significant implications for both fundamental science and practical applications.

Affiliations

UCLouvainSST/ELI - Earth and Life Institute

Citations

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Rothwell, M., D’Agostino, M., Degand, T., Ding, L., Thiébaut, N., & Couvreur, V. (2025). Osmotic and Hydraulic Dynamics of Trees Under Water Deficit. UMR BioGeco Seminar, Université de Bordeaux. https://hdl.handle.net/2078.5/271872