In this project, we studied how soil microbes “self-organize” across different spatial scales. Our goal was to uncover how their interactions shape the way organic matter is broken down and how carbon is stored or released from soils.
At the microscopic scale, we combined experiments and computer models to study how microbes cooperate to break down complex substances such as cellulose or chitin. We found that microbes face important trade-offs: they must invest in enzymes to unlock food sources, but the effectiveness of these enzymes depends strongly on soil structure. Tiny soil pores can limit enzyme activity even more than the microbes’ own biology. These trade-offs create thresholds, where small changes in conditions can cause abrupt shifts in microbial activity.
At a slightly larger scale, we examined microbial communities in millimeter-sized soil aggregates. By analyzing both the microbes present and the chemistry of the aggregates, we discovered that the soil microbiome is highly structured and diverse at small scales. Some microbial groups are associated with “fresh” organic matter, while others are linked to more decomposed material. These findings show how soil structure shapes microbial communities, and how microbial evolution and ecology are tied to the state of organic matter at fine scales.
We also explored network analysis, a method commonly used to study microbial co-occurrence patterns. Our theoretical work revealed that the environmental context and sampling strategy strongly influence these networks. Importantly, we showed that smaller sampling units (like individual aggregates) preserve ecological signals better than large, mixed samples, which can blur the patterns.
At the ecosystem scale, we studied long-term field experiments. In Austrian grasslands, we found that 70 years of nutrient depletion caused complex shifts in soil fungi, linked to changes in plant communities and soil chemistry. In Iceland, we examined soils along a natural geothermal warming gradient. Here, microbial activity and soil carbon showed non-linear responses to warming, suggesting that soils may pass critical tipping points under environmental change.
Overall, our project demonstrates that soil microbial ecosystems behave like complex systems, showing self-organization, trade-offs, feedbacks, and tipping points. These findings advance our understanding of how soils function and how they may respond to global change.
Dissemination of results
The project’s results were shared through peer-reviewed publications, conference presentations, and preprints on BioRxiv. Some findings are already published in international peer-reviewed journals (e.g. Nature Geoscience, ISME Journal, PLOS Computational Biology), while others are under review, and available as preprints on BioRxiv. The work has been presented on conferences, both within the soil science community and at interdisciplinary meetings on complex systems and mathematical modeling.
