| In the face of the ongoing and predicted climate warming in northern Europe, it is crucial to improve our understanding of the factors regulating long-term carbon storage in boreal forest soils. Boreal forests contain a large proportion of the global soil carbon stock, and if released through decomposition it could amplify the atmospheric warming potential. This project investigates how decomposition rates change in a chronosequence of 30 boreal forests ranging in age between 50 to 5300 years. The vast majority of studies on how decomposition processes may feed back to global change have focused on the first two years of the litter decomposition phase. This project will focus on the later decomposition phases acting in time perspectives of decades to centuries. This will be done by employing carbon-14 dating of fine-scaled organic soil profiles to calculate carbon turnover and to relate this to changes in enzyme activities and carbon chemistry in the profiles. We aim at testing the two main hypotheses: i) that decomposition of organic matter progress in two distinct phases: a fast litter decomposition phase and a slow humus decomposition phase, each with characteristic carbon-nutrient dynamics and decomposer communities, and ii) that long-term succession-related differences in soil carbon accumulation are largely explained by different accumulation rates during the slow humus decomposition phase.
There is currently a vivid debate about how Sweden's forest resources should be distributed between production-oriented forestry at different intensity levels and nature reserves promoting conservation of forests at late successional stages. The potential of differently managed forests to act as carbon sinks is an important factor in such decisions. This project will be carried out in cooperation with two strong research environments within Mycology and Ecosystem Ecology, and we fully expect that the outcome of the project will contribute to improved understanding of the main drivers of long-term carbon storage in boreal forests. In particular, the project will gain insight into the processes which work to preserve carbon stocks in old natural boreal forest soils in the long term perspective.
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