Simulations of the terrestrial carbon cycle using DGVM under RCPs scenarios

The changes of vegetation distribution due to the climate change and anthropogenic land use alternations have great impacts on terrestrial carbon cycles. To examine these impacts, a Spatially Explicit Individual-Based Dynamic Global Vegetation Model (SEIB-DGVM; Sato et al., 2007) was developed. This is a process-based model that can simulate the growth, competition, and decay of individual trees within a virtual plot where individual trees composed of several Plant Functional Types (PFTs) compete for light and space. This model can also simulate the decomposition process of litter and soil organic matters. In addition, to represent the effects from the anthropogenic land use change, SEIB-DGVM incorporates land use datasets of representative concentration pathways (RCPs) scenarios (Hurtt et al. 2009) for 1500-2100. Its land use types are summarized into five categories: primary vegetation, secondary vegetation, pasture, cropland, and urban area. Their transitions are reproduced by a dataset of fractional changes of land use area in each grid of SEIB-DGVM. Carbon in harvested biomass is transferred into carbon pools of linear decay according to Grand Slam Protocol described in Houghton et al. (1983). These anthropogenic land use change will alter the vegetation structure and carbon cycle in terrestrial ecosystems. Using this model, we conducted transitional simulation experiments in global scale from 1850 to 2100 to examine the anthropogenic impacts on terrestrial ecosystems and carbon dynamics. The results showed that land use changes have significant impact on the carbon stored in vegetation and soil and alter the carbon fluxes between atmosphere and terrestrial ecosystems.