Worldwide, trees are threatened by climate change. They must cope with a multitude of stressors, including drought. One of the critical global challenges of our current generation is predicting how trees respond to climate change and these stressors. How can we determine the transition from a healthy to an unhealthy state, and how can we detect early signs that a critical threshold is about to be crossed?
A combination of plant sensors and mechanistic plant modelling enables to capture plant hydraulic functioning in fine detail and, hence, early signs of stress responses (Steppe et al. 2015). This results in novel technology and applications to, for instance, assess and automatically distinguish between atmospheric and soil drought stress (Van de Put and Steppe 2022).
Critical thresholds that define the transition from a healthy to an unhealthy tree are known to be affected by CO2. Here, not only the potential of elevated atmospheric CO2 concentration in mitigating adverse effects of drought on leaf and whole-tree functioning is important to consider (Lauriks et al. 2022a,b). Also tree internal, locally respired CO2 might play a crucial role in tree survival under climate-change-driven drought, especially when it is refixed by woody tissue photosynthesis (De Baerdemaeker et al. 2017, De Roo et al. 2020a,b). Such studies help us to revisit predictions of tree water transport dynamics and tree water management under climate change scenarios.