The Interactions between Biogeophysical and Biogeochemical Processes and their Feedbacks on Permafrost Soil Carbon Stocks
The terrestrial Northern high-latitude (NHL) regions above permafrost are considered to be most vulnerable to climate change, and the dynamics of carbon fluxes in these regions is likely to have tremendous impacts for the future global climate. One of the challenges in more detailed Earth system models (ESMs) is the treatment of the biophysical and biogeochemical processes and feedbacks and their impact on soil organic carbon in NHL. In this talk, I will investigate the feedbacks between the biogeochemical and biogeophysical processes and their impacts on a model estimated soil organic carbon (SOC) for the NHL permafrost region using a land surface model, the Integrated Science Assessment Model (ISAM).
We not only focus on recent model improvements in the biogeophysical processes that are deemed important for the high latitude soils/snow; such as deep soil column, modulation of soil thermal and hydrological properties, wind compaction of snow, and depth hoar formation; on permafrost SOC; but also biogeochemical processes; such as dynamic phenology and root distribution, litter carbon decomposition rates and nitrogen amount remaining; on soil biogeochemistry. We select multiple sites to evaluate the model. We then carried out several model simulations to study the effects of feedbacks between biogeochemical and biogeophysical processes on SOC. Our model analysis shows that including the biogeophysical processes alone could increase modeled NHL permafrost carbon by about 30%. Accounting for the biogeochmical processes further improve the NHL soil carbon.