Towards better assessments of nutrient constraints on soil carbon sequestration: including soil microbial and mineral mechanisms into the terrestrial biosphere models
Soils contain the largest carbon (C) pool in terrestrial ecosystems, and the capacity of soils to sequestrate C is thus important for climate mitigation. However, model uncertainties caused by inadequate process descriptions of carbon-nutrient interactions lead to high uncertainties in the future projections of terrestrial C sequestration. The aim of this project is to include soil microbial and mineral mechanisms into a terrestrial biosphere model (TBM), to improve the assessments of nutrient constraints on soil C sequestration. A combined approach of process-based modelling and soil measurements from four forest sites will be used in two sub-studies: (1) improving the representations of carbon-nutrient interactions of a soil C model, which already contains microbial and mineral mechanisms, to be able to quantify the effects of microbial mechanisms on soil organic matter formation/turnover and (2)coupling this soil C model with a TBM to investigate the nutrient constraints on soil C sequestration, and applying the improved TBM on 544 forest sites in a national database to investigate the effects of nutrient constraints on soil C sequestration across Sweden. The improved model will be capable of better predicting the effects of management strategies on C sequestration, to provide more robust decision support.