"All forest species are equally susceptible to drought," junior professor steven jansen of the university of ulm told the dpa news agency. Particularly in humid areas, trees do not put any additional energy into the water supply and then suffer from climatic changes. The team of 23 researchers presents the results of its three-year work in the scientific journal "nature".
Researchers of the ARC-NZ research network for vegetation function found that trees adapt optimally to their location by making efficient use of the available water. "If environmental conditions change, they are prone to drought-related mortality," biologist jansen said in a statement. "This vulnerability can be demonstrated for all habitats – whether wet or dry."
The water transport system in trees is very finely tuned, but also very fragile. The water is sucked up mainly by evaporation on the leaves and needles. In times of drought, the system is under severe suction stress, and if it continues to dry out, the water brine can even wear off. As a result, air bubbles were able to accumulate in the conduits of the trees, which blocked the further flow of water. The result: the plant dries out more and more, in the worst case it dies. "This situation resembles an embolism in humans, where a clot interrupts the blood flow," jansen continued.
High temperatures and long dry spells can have dramatic consequences, says jansen. However, he does not believe in a global forest dieback: "some plants will adapt to the changed conditions quickly enough, others may thrive in new locations."