Impact of Drought and Legacy Effects on Tree-Crown Biodiversity: Exploring the Interplay Among Phytochemistry, the Leaf Microbiome and Insect Herbivores

The growing number of severe summer droughts and therewith associated forest canopy mortality poses a serious threat to forest biodiversity. The goal of this project is to study how drought severity and drought legacy effects modulate the interaction among phytochemical, bacterial, and herbivore diversity as well as herbivore behaviour and leaf damage patterns in Norway spruce and European beech, two dominant tree species in Central Europe. We propose a novel combination of long-term drought manipulation in the field and controlled laboratory experiments to study tree-bacterial-insect interactions. Using the established throughfall exclusion experiment in Kranzberg Forest (Germany) paired with controlled climate chamber assays, we will investigate the impacts of drought severity and drought legacy on leaf chemodiversity, and how this affects the relationship amongst leaf bacterial and herbivore diversity as well as herbivory.