SUREAU Team

SurEau team analyses the hydraulic functioning of trees and its link to severe droughts that can lead to their decline.

Climate models predict an increase in the intensity and frequency of extreme droughts, but little is known about how trees, and ecosystems more generally, respond to these events. Sap circulates under tension in the xylem and is at risk of cavitation (vapourisation of the sap) when drought exacerbates these tensions. This phenomenon leads to a loss of xylem conductance, known as embolism. If the tension is too high, the organs are no longer supplied with water. The hydraulic safety of trees therefore plays an important role during severe droughts, and it is on this process that the team is focusing its research efforts. The main scientific objective of the SurEau team is to predict the risks of hydraulic dysfunction leading to tree decline, according to climate change scenarios.

To formulate hypotheses about these risks of hydraulic failure, we have the SurEau model at our disposal. The development of this model provided an opportunity to reconsider drought resistance by shifting from a scale of intensity (water potential) to a scale of duration. Thus, understanding this resistance as the ability to delay hydraulic dysfunction encourages us to reconsider the contribution of hydraulic safety traits. Assessing the role of these traits also involves characterising their variability, particularly in a changing climate. Furthermore, to refine the model's predictions, we need to elucidate the mechanisms of tree mortality and the link with hydraulic dysfunction.

The SurEau team is also developing original tools (Xyl'em, Cavitron, irrigation control, Drought-box) and acquiring others (e.g. Microtomograph, Cavicam) to drive forward projects at the forefront of science. Some of these tools are integrated into INRAE's Phenobois platform (phenotyping of the physico-chemical properties of wood and the hydraulic properties of trees).