The International Research Training Group TreeDì - 林地 (lín dì, forest land) investigates how tree-tree and tree-shrub interactions in forests translate into positive species richness effects on multiple key ecosystem functions. TreeDì goes beyond preceding Biodiversity-Ecosystem Functioning (BEF) research by studying mechanistic processes at the relevant local scale instead of inferring them from the community scale. In addition to selection effects brought about by the taxonomic or functional identity of tree and shrub species, TreeDì focuses on four main groups of mechanisms: 1) resource partitioning, which results in an increased and more efficient resource use, 2) facilitation, which ameliorates abiotic stress, 3) dilution effects, which reduces the negative effects of herbivores and pathogens on trees and shrubs and 4) biotic feedbacks of higher trophic levels on ecosystem functions.

On the BEF-China platform, the individual PhD projects test the overarching hypothesis that positive net biodiversity effects at the community scale emerge from the sum of these processes at the scale of local neighbourhoods. While each project has specific objectives, they complement each other synergistically and interdisciplinarily. This "zoom-in"-approach requires an interdisciplinary team of experts from forestry, functional plant ecology, zoology, molecular biology, microbial ecology, soil ecology, metabolomics and modelling. TreeDì features an international qualification programme, involving an intensive Chinese-German cultural exchange during mutual research visits, a joint PhD advisory committee composed of Chinese and German principal investigators and unique opportunities to meet, study and discuss with key researchers in biodiversity research.