ERC Starting Grant: Mycorrhizal Types and Soil Carbon Storage: A mechanistic theory of fungal mediated soil organic matter cycling in temperate forests

MYCO-SoilC

The world's soils are the largest terrestrial reservoir of organic carbon (C). Feedbacks between soil organic C and atmospheric CO₂ will determine the future trajectory of climate change. However, predictions are largely uncertain because we still lack fundamental knowledge of the complex interplay between plants and microorganisms and its influence on C turnover.
Most terrestrial plants live in symbiosis with mycorrhizal fungi. Previous work suggests that on a global scale soil C stocks are linked to the distribution of arbuscular mycorrhizal (AM) or ectomycorrhizal (ECM) plants. To date, it is not clear whether there is a causal relationship between mycorrhizal type and soil C storage. Answering this key question requires novel concepts that consider the mechanistic link between short-term C fluxes from plants to mycorrhizal fungi and C storage as an emerging ecosystem property.

Characteristic features of arbuscular and ectomycorrhiza. Drawing by Katrin Giesemann.

MYCO-SoilC will yield a comparative, systematic understanding of the dynamics of C input by mycorrhizal fungi to soil, their effects on C turnover and their implications for C storage in temperate forests dominated by AM or ECM trees. Achieving this ambitious goal, which involves a multitude of processes on different spatio-temporal scales, requires the development of ground-breaking technological innovations. Key innovations of MYCO-SoilC are 1) real-time visualization of ¹¹C allocation in plant-soil systems, 2) construction of the first moving greenhouse for ¹³CO₂-labeling of mini-forests, 3) coupling of quantum dot nanotechnology with isotope labeling to visualize organic nutrient uptake by fungi, and 4) combining isotope analysis with biomarker approaches to quantify the fungal necromass contribution to soil C. MYCO-SoilC will create substantial knowledge on mycorrhizal mediated C turnover and facilitate predictions of soil-climate feedbacks.