S. Mölk (2024)
Ecophysiological responses to the soil water content in eight Fagus sylvatica L. provenances, Masterarbeit, FU-Berlin

Abstract

Climate change will affect species composition in all ecological regions of the world, with an in-creased incidence of drought expected to limit plant growth due to reduced soil water availabil-ity. Forest ecosystems, including the broadleaved forests of Central Europe, are expected to suffer greatly from these predictions, with key species such as Fagus sylvatica L. being affected. Despite Fagus sylvatica L. showing strong negative responses to drought in the past years, its conservation remains crucial for the maintenance of local biodiversity. The wide distribution of the species from north to south and from east to west - from Sweden to Sicily and from Spain to Ukraine - indicates its ability to adapt to different climatic conditions. To assess whether Fagus sylvatica L. provenances differ in their response to decreasing water availability, two parameters were investigated in detail: a) daily water consumption (WC) as a function of provenance and tree size, and b) the effect on leaf water potential (Ψ). Eight provenances from the distribution area (Austria, Germany, Spain, France, Italy, Poland, Sweden, Serbia) were studied in an outdoor experiment in Grunewald, Berlin, over a period of 36 days. Trees were monitored starting at well-watered conditions and left with-out watering until the end of the experiment. While small differences in WC between provenances were observed, no significant results were obtained. However, tree size had an effect on normalised WC per stem area for all provenances. Ψ was measured at three dfferent soil water content (SWC) levels representing relaxed, lightly stressed and stressed conditions. A strong effect of SWC on pre-dawn and mid day Ψ was observed for all provenances, with no significant differences between provenances. These results suggest possible provenance-specific responses, but primarily provide general insights into WC as well as drought responses through Ψ for Fagus sylvatica L.