Simulation of water and carbon fluxes using BIOME-BGC model over crops in China

Many ecosystem models have been developed for simulating water and carbon exchanges between the atmosphere and terrestrial ecosystems. One, the biogeochemical cycles (BIOME-BGC) model, simulates the storage and fluxes of water, carbon and nitrogen within the vegetation, litter and soil components of a terrestrial ecosystem. The model permits sophisticated simulations of natural ecosystems such as forest, grassland and shrub-land. However, it has rarely been applied to agricultural ecosystems. This study was conducted for exploring the ability of the BIOME-BGC for crops in China. For this propose, we set up an eddy-covariance tower in the North China Plain in 2002 and have obtained both flux data and related data of meteorological, vegetation and soil properties. By using these observation data, we modified eco-physiological parameters in the model. Correspondence between the simulated results with observations suggested that the modified model can be used to predict crop growth as well as water (H2O) and carbon (CO2) fluxes under the consideration of the effects of anthropogenic forcing. To estimate the effects of anthropogenic forcing, we executed the model simulation under two scenarios: undisturbed and disturbed. The undisturbed scenario aimed to simulate potential plant growth and functioning with natural levels of atmospheric CO2 and nitrogen deposition, but the effects of anthropogenic forcing were simulated in the disturbed scenario. Results showed that the simulated H2O and CO2 fluxes are higher in the disturbed scenario than those in the undisturbed scenario, which suggests that anthropogenic forcing had an apparent effect on the water and carbon fluxes and sequestration capacity. However, simulation also indicated that nitrogen application from chemical fertiliser is greater than the requirements of crops, which might cause water and soil pollution in the study area.