P5G: Drivers of leaf fungal pathogen load (TreeDì_P5G leaf fungi)

Foliar fungal pathogens negatively affect plant performance, directly or indirectly by changing the outcome of competition. In contrast, it is not known how leaf fungal pathogen infestation affects other ecosystem functions such as leaf litter decomposition. As leaf litter decomposition is dependent on the chemical composition of the leaf tissue and fungi feed on organic compounds in the leaf, fungal infection can be expected to have an effect on leaf decomposition rates. There is also evidence that leaf inhabiting fungi play a direct role in leaf litter decomposition. Leaf fungal pathogens are mostly highly host-specialized, which also applies to the BEF-China experiment. In the BEF-China experiment, both fungal richness and fungal infestation increase with increasing proportion of conspecifics in the local neighbourhood. Such neighbourhood effects are thought to be mediated by the modification of sun exposure, local microclimate or soil conditions. Objectives: to estimate the leaf area infected by fungal pathogens to identify all fungal species found on the TSP trees, using morphological and molecular approaches to monitor pathogen load and fungal species richness under different crown interaction points of TSPs and to relate these patterns to microclimate to study the effect of pathogen load on tree productivity