Trait-based modeling of microbial processes in soil
Dr. Holger Pagel
University of Hohenheim
Institute of Soil Science and Land Evaluation/ Biogeophysics
Integrating trait-based approaches to describe microbial dynamics in biogeochemical models gained momentum to improve the understanding and prediction of microbial controlled processes in soil. At the same time, microscopic observations and pore scale models are increasingly used to quantify and elucidate the effect of soil heterogeneity on microbial processes. These developments empower capturing and predicting the emergence of spatial and temporal variability of microbial processes from small-scale microbial-physicochemical interactions in soil. The current challenge is, however, to quantify and identify ecologically meaningful microbial traits. The central objective of my research is to integrate functional traits of soil microorganisms into models. On the one hand, quantitative data on functional genes and gene transcripts is used in combination with isotopic data to inform gene-based models that simulate pesticide degradation as a narrow process carried out by a relatively small subset of microbial taxa. One the other hand a new spatially explicit trait-based model is used to simulate soil organic matter (SOM) turnover as a broad process carried out by a broad diversity of taxa. This model considers microbial life-history traits and dormancy as well as SOM accessibility. To elucidate the spatial control of C turnover in soil, Monte-Carlo scenario simulations for sets of spatial distributions of microbes that differ in small-scale spatial heterogeneity and functional composition of the microbial community were performed. First results show that the spatial distribution of microorganisms mainly affects the dynamics and relative proportion of functional groups, but only slightly affects SOM turnover. Ongoing work targets at identifying key functional groups with respect to growth rate and substrate utilization based on 13C DNA stable isotope probing data.