Trees and water shortage: estimating the vascular factor.

Trees transport water from roots to leaves over several to more than 100 meters. Already when water is plenty this is astonishing, but how do trees meet their water needs in conditions of water shortage? Trees facing permanent or periodical drought are however not exceptional. Two important examples are: mangrove trees, facing the unavailability of water due to high salt concentrations in the water of the coastal zones, and mediterranean trees, facing extreme water shortage during summer drought. In this project I plan to investigate the tubes that transport the water inside the tree in relation to drought in both tree groups.
How is the water transporting system inside the tree adapted to make the tree survive during drought? In a first approach, I will study the inside structure of trees along a gradient of intensifying drought stress. This will allow me to observe the differences between trees
growing in conditions with more or less water shortage. In a second approach, I will observe the water transport inside trees through MRI scanning, a technique that makes the water molecules and their flow visual in living trees. I will do measurements before and after extreme drought conditions. In a third approach, I will study the evolution of the inside water transporting structure by comparing closely related trees growing under drought and without drought. The combination of the three approaches will bring understanding in how trees can live when there is a lack of water.