Foliar water uptake, beech’s (Fagus sylvatica L.) savior in times of drought
Abstract
Water limitations at the root-level are expected to become more common as climate change progresses. Such events have already led to worldwide observations of drought-induced forest degradation and tree dieback. In order to survive these catastrophic changes in the water budget of forests, trees are forced to bypass the soil water availability. Foliar water uptake (FWU) is one of the possible plant traits that could allow such a side-step from soil water and could thus ameliorate the detrimental effects of these drought events. FWU has been intensively studied for tree species originating from the tropics, however, studies focussing on this plant trait in the temperate region are lacking. As such, FWU was investigated for European beech (Fagus sylvatica L.) saplings during a drought event. It was found that FWU did occur in beech. Even more, an increasing amount of water was taken up by the leaves during more severe drought, which led to a higher leaf water potential and hence improved the leaf water status. The amount of water taken up by FWU strongly correlated with the initial leaf water potential and was predominantly driven by the vapour pressure deficit and the soil water potential during well-watered and dry soil conditions, respectively. These results indicate that FWU can partly ameliorate the damaging effects of climate change associated drought events, highlighting the importance of this plant trait in temperate regions in the nearby future.
