Project C2 will study the vulnerability of soil OC stocks to changes in climate and land use in the Nam Co region by 1) integrating information on C and N cycling and their isotopic composition along an elevation and permafrost gradient into a predictive model, 2) developing a laboratory study to explore the response of microorganisms to freeze-thaw cycles, and 3) perform predictions of changes in soil C to different scenarios of changes in climate and land use. It will use the information generated on soil organic C and N storage, its variability and cycling (Project C1 and its Chinese sister project), and other existing information to derive and test different models of soil organic matter dynamics.
In addition, we will measure radiocarbon concentrations (14C) in bulk soil and respired CO2 at the AMS facility of MPI-BGC, and will integrate measurements of 13C in respired CO2 (project C1) for a comprehensive dual-isotope assessment of soil C cycling. We will develop a model that can integrate the different sources of information with the objective to scale up the results to the landscape and regional levels. At MPI-BGC an incubation experiment under controlled conditions of temperature, moisture and oxygen concentrations will be conducted to evaluate the response of microbial activity under freeze-thaw cycles and develop possible mathematical functions that can be incorporated in the model. After the identification of the most appropriate model to represent the data, we will run simulations with specific scenarios of changes in climate and land-use. The objective is to assess: 1) whether soils in the study area will act as sources or sinks of C under current climatic conditions and under a rapid climate change scenario; 2) whether changes in soil C in the study area are more sensitive to changes in climate or land-use; 3) what type of ecosystems within the study area are more vulnerable to C losses.
The partners from ITP will focus on CH4 production and oxidation and will enter data gathered from field and laboratory experiments into a common modeling framework that allows for testing multiple model structures and produce predicitions including uncertainty estimates. Furthermore, in a joint effort with FSUJ/MPI-BGC models will be improved to account for interactions among microbes and substrates at the freezing point of water, which is a major uncertainty in modeling the C cycle. Our code and model output will be available for both groups for further research.
Dr. Carlos Sierra, MPI Jena
Prof. Dr. Guggenberger, LU Hannover
Prof. Dr. Xu Baiqing, ITP