Preprints
https://doi.org/10.5194/gmd-2022-17
https://doi.org/10.5194/gmd-2022-17
Submitted as: model description paper
16 Mar 2022
Submitted as: model description paper | 16 Mar 2022
Status: this preprint is currently under review for the journal GMD.

SurEau-Ecos v2.0: A trait-based plant hydraulics model for simulations of plant water status and drought-induced mortality at the ecosystem level

Julien Ruffault1, François Pimont1, Hervé Cochard2, Jean-Luc Dupuy1, and Nicolas K. Martin-StPaul1 Julien Ruffault et al.
  • 1INRAE, URFM, 84000 Avignon, France
  • 2Université Clermont Auvergne, INRAE, PIAF, 63000 Clermont-Ferrand, France

Abstract. A widespread increase in tree mortality has been observed around the globe, and this trend is likely to continue because of ongoing climate-induced increases in drought frequency and intensity. This raises the need to identify regions and ecosystems that are likely to experience the most frequent and significant damages. We present SurEau-Ecos, a trait-based, plant-hydraulic model designed to predict tree desiccation and mortality at scales from stand to region. SurEau-Ecos draws on the general principles of the process-based, soil-plant-atmosphere SurEau model. It also introduces a simplified representation of plant architecture and alternative numerical schemes; both additions made to facilitate model parameterization and large-scale applications. In SurEau-Ecos, the water fluxes from the soil to the atmosphere are represented through two plant organs (a leaf and a stem, which includes the volume of the trunk, roots and branches) as the product of an interface conductance and the difference of water potentials. Each organ is described by its symplasmic and apoplasmic compartments. The dynamics of plant’s water status beyond the point of stomatal closure are explicitly represented via residual transpiration flow, plant cavitation and solicitation of plants’ water reservoirs. In addition to the "explicit” numerical scheme of SurEau, we implemented a “semi-implicit” and “implicit” scheme. Both schemes led to a substantial gain in computing time compared to the “explicit” scheme (>10,000 times), and the implicit scheme was the most accurate. We also observed similar plant water dynamics between SurEau-Ecos and SurEau but slight disparities in infra-daily variations of plant water potentials that we attributed to the differences in the representation of plant architecture between models. A global model’s sensitivity analysis revealed that factors controlling plant desiccation rates differ depending on whether leaf water potential is below or above the point of stomatal closure. Total available water for the plant, leaf area index, and the leaf water potential at 50 % stomatal closure mostly drove the time needed to reach stomatal closure. Once stomata are closed, resistance to cavitation, residual cuticular transpiration and plant water stocks mostly determined the time to hydraulic failure. Finally, we illustrated the potential of SurEau-Ecos to simulate regional drought-induced mortality over France. SurEau-Ecos is a promising tool to perform regional-scale predictions of drought-induced hydraulic failure, determine the most vulnerable areas and ecosystems to drying conditions, and asses the dynamics of forest flammability.

Julien Ruffault et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2022-17', Miquel de Cáceres, 29 Mar 2022
  • RC2: 'Comment on gmd-2022-17', Xiangtao Xu, 05 Apr 2022

Julien Ruffault et al.

Julien Ruffault et al.

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Short summary
Increasing drought conditions are a threat to forest ecosystems around the world. Here we present SurEau-Ecos v2.0, a plant hydraulic model designed to predict predict tree desiccation and mortality. This model will help to determine the most vulnerable areas and ecosystems to drying conditions, and asses the dynamics of forest flammability.