Key message

A new process-based model, SurEau , is described. It predicts the risk of xylem hydraulic failure under drought.

Context

The increase in drought intensity due to climate change will accentuate the risk of tree mortality. But very few process-based models are currently able to predict this mortality risk.

Aims

We describe the operating principle of a new mechanistic model SurEau that computes the water balance, water relations, and hydraulics of a plant under extreme drought.

Methods

SurEau is based on the formalization of key physiological processes of plant response to water stress. The hydraulic and hydric functioning of the plant is at the core of this model, which focuses on both water flows (i.e., hydraulic) and water pools (i.e., hydric) using variable hydraulic conductances. The model considers the elementary flow of water from the soil to the atmosphere through different plant organs that are described by their symplasmic and apoplasmic compartments. For each organ, the symplasm is described by a pressure-volume curve and the apoplasm by its vulnerability curve to cavitation. The model is evaluated on mature oak trees exposed to water stress.

Results

On the tested oak trees, the model captures well the observed soil water balance, water relations, and level of embolism. A sensitivity analysis reveals that the level of embolism is strongly determined by air VPD and key physiological traits such as cuticular transpiration, resistance to cavitation, and leaf area.

Conclusion

The process-based SurEau model offers new opportunities to evaluate how different species or genotypes will respond to future climatic conditions.

中文翻译：

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SurEau：极端干旱下植物水分关系的机械模型

关键信息

描述了一种新的基于过程的模型 SurEau 。它预测干旱下木质部水力故障的风险。

语境

气候变化导致的干旱强度增加将加剧树木死亡的风险。但目前很少有基于过程的模型能够预测这种死亡风险。

宗旨

我们描述了一种新的机械模型SurEau的工作原理，该模型计算极端干旱下植物的水平衡、水关系和水力学。

方法

SurEau基于植物对水分胁迫反应的关键生理过程的形式化。工厂的水力和水力功能是该模型的核心，该模型侧重于使用可变水力传导的水流（即水力）和水池（即水力）。该模型考虑了水通过不同植物器官从土壤到大气的基本流动，这些器官由它们的共质和质外质区室描述。对于每个器官，共质由压力-体积曲线描述，质外质由其对空化的易损性曲线描述。该模型在暴露于水分胁迫的成熟橡树上进行评估。

结果

在测试的橡树上，该模型很好地捕捉了观察到的土壤水平衡、水关系和栓塞水平。敏感性分析表明，栓塞的程度很大程度上取决于空气 VPD 和关键生理特征，如表皮蒸腾作用、抗空化和叶面积。

结论

基于过程的SurEau模型为评估不同物种或基因型对未来气候条件的反应提供了新的机会。