P07 Drivers of microbial nutrient turnover in mineral soil, rhizosphere, and forest floors

In Project 7, we investigate the microbiological aspects of the forest floor (FF). Although forest soils are renowned for their vast diversity of microbes and have been extensively researched, the forest floor remains a relatively understudied ecosystem. FF properties influence nutrient concentrations and quality as well as oxygen and water availability. The turnover of nutrients by microorganisms is regulated on the level of nutrient stoichiometry of ecosystems and genetic operon structure of single microorganisms who pursue different strategies to regulate efficient nutrient use. Thus, nutrient availability and community composition are closely interlinked. Consequently, changes in nutrient availability and habitat structure because of increasing temperature feedback on microbial communities in terms of their taxonomic and functional composition as well as trophic interactions.

The aim of P7 is to understand the interplay of abiotic FF properties with the microbial community composition under different P and temperature regimes.

We aim to identify the adaptations of microbial communities involved in phosphorus and nitrogen turnover along gradients of phosphorus availability and temperature. We hypothesize that the quality and quantity of soil organic matter and root exudates as well as nutrient stoichiometry (C, N, P, cations) drives the microbial potential to transform nitrogen and phosphorus and determines trophic interaction with other biota (fungi, fauna, and trees).

To explore forest floor microbiomes and their potentials, we will apply qPCR and amplicon sequencing, as well as metagenomic shotgun sequencing, microbial biomass determination, fluorescence in situ hybridization (FISH) and isolation techniques. Next to sampling of forest floor layers and compartments at high resolution, we will utilize mesocosm and litterbag approaches for our experimental designs.

Results from P7 will widen the understanding about microbial nutrient turnover in the forest floor and the impacts of climate, litter quality and phosphorus availability.