Soil heterotrophic microorganism and mycorrhizal diversity
With an exhaustive evaluation of soil microbial diversity in monospecific tree stands and in mixed-species tree stands using molecular approaches (next generation sequencing), we evaluate whether tree species richness and soil microbial diversity are related.
Soil fauna diversity
Using common field sampling techniques, we measure the diversity and abundance of soil micro- and macroarthropods, earthworms, and nematodes to establish possible links between tree diversity and soil fauna diversity. With available trait databases, the functional structure of soil fauna communities and their relationship to functional tree diversity is explored.
Fine root traits
We quantify functional traits of fine roots and their spatial arrangement within soil profiles at the level of tree neighborhoods, where root systems of adjacent trees interact. This will allow us to evaluate belowground niche occupation by tree fine roots as a function of tree species taxonomic and functional diversity and to determine if and how fine root traits are related to the diversity of other soil organisms.
Relationships among below- and aboveground diversity indices
All soil biodiversity data from the six groups of organisms will be used to thoroughly evaluate the relationships between above- and belowground biodiversity with multivariate approaches. Emerging relationships and hypotheses are further tested using structural equation modelling (SEM).