Foliar water uptake as a mitigating strategy for drought under elevated CO2 concentrations in beech (Fagus sylvatica L.)

Foliar water uptake has been indicated as a global phenomenon across an increasing number of plant species. Although its relevance as a mechanism to aid plants in maintaining their hydraulic functioning, our knowledge of its contribution to the plant’s water status under the projected climate change conditions remains limited. An increase in average air temperature, alterations in precipitation patterns and a doubling of current CO2 levels by the end of the century will lead to an increase in frequency and intensity of drought periods. The latter highlights the increasing potential importance of foliar water uptake in the nearby future. The proposed research is therefore aimed at elucidating the mitigating effect of foliar water uptake under ambient and elevated CO2, and different drought stress conditions on beech tree hydraulics. Saplings will be grown in treatment chambers in which environmental factors such as temperature, [CO2] and soil water content can be controlled, simulating future conditions for these trees. The impact of artificial rainfall events under these different growth conditions will be assessed by a combination of plant sensors and discrete physiological measurements. In this way, this research strives to improve clarity for forest managers and policy makers about the uncertain and heavily debated position of beech, a tree species with an economic and ecological key role in our forests of Central Europe.