Organic matter often sticks to minerals, forming what is known as mineral-associated organic matter, likely representing the most stable carbon and nutrient pool in soils. Fungi play a key role in these stabilization processes by regulating the chemical transformation of particulate and dissolved organic molecules eventually adsorbed on minerals. Yet, they can also destabilize mineral and organic matter complexes to extract carbon and nutrients through diverse mechanisms. My research focuses on understanding the strategies employed by soil fungi to obtain mineral-associated carbon, nitrogen, and phosphorus, their evolutionary basis, and their subsequent impact on forest biogeochemical cycles.

Saprotrophic and ectomycorrhizal fungi co-dominate soil mycobiomes in temperate and boreal forests. The saprotrophs extract carbon from decomposing organic matter, while ectomycorrhizal fungi obtain carbon from host trees in exchange for nutrients. Both fungal functional groups compete for soil nutrients. Ectomycorrhizal fungi’s nutrient mining, sometimes even directly targeting organic nutrients, is suspected to impact soil organic matter decomposition rates, either slowing or speeding decay. I am studying the capacity of a large set of ectomycorrhizal species for organic nutrient acquisition to enhance understanding and prediction of their effects on organic matter decomposition and tree nutrition.

Annually, dozens of gigatons of atmospheric carbon are transferred into fungal biomass. This occurs both directly via plant transfer to their mycorrhizal symbionts, and indirectly through the decomposition of plant residues by fungi. Yet, what becomes of the carbon incorporated into this fungal biomass remains largely unknown. Recent data, however, suggest that fungal necromass carbon significantly contributes to the soil organic carbon pool. In my research, I strive to unravel the biotic and abiotic factors influencing the decay of mycelial residues. While bacteria and fungi serve as the primary decomposers of fungal necromass, my recent work also considers other critical players in the microbial food web. These include protists and nematodes that prey on primary microbial decomposers. This diversified focus aids in deepening our understanding of necromass carbon's fate.

Fungi play a central role in numerous forest ecosystem functions, such as carbon sequestration and tree productivity. Yet, the impact of natural disturbances and anthropogenic activities on these fungal communities—and how they contribute to these crucial forest processes in our (too) rapidly changing world—remains largely unexplored. Across various experimental networks spanning Europe and North America, I aim to determine how fungi respond to disturbances like drought and flooding events, as well as to intensive forest management practices. I examine this in terms of both fungal compositional and functional diversity. The findings should assist in incorporating fungal components into forest biogeochemical models, thus improving the prediction of fungal-mediated forest processes' resilience and resistance to disturbances.