Abstract
Forests play a critical role in the global carbon cycle, being considered an important carbon sink. Yet their net carbon exchange response to environmental change is a major uncertainty, with a particularly poor understanding of the origins and environmental responses of soil CO2 efflux. Despite their large biomass, the contribution of roots and extramatrical mycelia (EMM) to forest soil CO2 efflux and responses to environmental change has, to date, not been quantified in Swedish spruce forests. The aim is to survey the production and turnover of fine roots and EMM in two drained coniferous soils to asses their importance for formation of recalcitrant C and contribution to soil respiration. This project will exploit recent advances in C isotope analysis of both contrasting SOM fractions and of respired CO2 by using a novel experimental mesh trenching design combined with in-growth mesh-tubes. Fine root dynamics and production will be studied using a newly developed scanner-based technology in combination with traditional soil coring technique. Soil microcosms installed in the field, filled with pure sand or C4-soil (naturally 13C-labelled) will detect changes in the decomposition or storage of new and old C. Sequential harvest of EMM in-growth mesh-tubes together with ergosterol and fatty acids analysis will give its production and turnover, for mycelia production. The results from this project will be highly relevant for global and ecosystem models of C cycling in forests.
Sweden