The ongoing anthropogenic climate change is immensely altering the structure and function of the terrestrial biosphere. In turn, the changing ecosystems have a strong potential to modify the climate through changes in biogeochemical cycles (e.g., C storage) and biophysics (e.g., albedo and hydrological cycling). Forest ecosystems will have particularly significant impacts onto the climate due to their large terrestrial coverage, vast C stock, and prominent biophysical characteristics. To reproduce the two-way interaction between vegetation and climate, climate models should be integrated with dynamically responding vegetation models with ecological processes such as reproduction, growth, and mortality. Here we present our recent progress, concerns, and future directions in simulations of vegetation processes by the terrestrial biosphere model (TBM) sSEIB (a simplified version of SEIB-DGVM: spatially-explicit, individual-based dynamic global vegetation model) that is coupled to a climate system model (Center for Climate System Research-Frontier Research Center for Global Change general circulation model, CCSR-FRCGC GCM).

Results/Conclusions

In the simulation study, sSEIB explicitly reproduces the ecophysiological, population, and community dynamics based on an individual-based forest model representation. Running with the current climatic conditions, sSEIB successfully reproduced the current global distributions of vegetation types, plant production, biomass, and soil organic carbon (uncoupled simulation). Then, the model was coupled to the CCSR-FRCGC GCM with an anthropogenic emission scenario (coupled simulation). The model system simulated a gradual rise in temperature during this century, and sSEIB reacted to the environmental changes and in turn affected the global C balance. Due to the climate change, distributions of plant types, biomass, and soil organic carbon were altered significantly. For example, colonization and growth enhancement of woody species in high-latitudinal regions were largely observed. In total, the terrestrial ecosystem acted as a C sink of approximately 5 PgC at the end of the 21st century.