A climate-vegetation interaction model: Simulating physical and biological processes at the surface

Annual variations of physical and biological processes at the surface were simulated with a climate-vegetation interaction model (AVIM). For the sake of consistency with the hierarchy of current climate models, it is assumed that the structure and functions of plant ecosystems in the simplified plant growth model are stable and in balance with soil and climatic environment. The model is constructed by coupling a plant growth physiological model with the soil vegetation atmosphere transfer (SVAT) scheme. The LPM, a SVAT-type scheme in the coupled model, includes energy and water transfer processes: radiation transfer and sensible heat exchange as well as rainfall, interception, drainage, surface runoff, infiltration, evapotranspiration, etc. In the plant growth model, living vegetation consists of three main biomass compartments: foliage, stem and root and the dead vegetation; a litter layer is also included. Photosynthesis, respiration, dry matter allocation in the tissues and decomposition of organic matter are taken into consideration. All these physiological processes are affected by photosynthetic active radiation, CO2 concentration in the atmosphere, temperature and moisture of air and soil which are predicted by the SVAT model. Meanwhile, the leaf area index, and then the roughness, albedo and other dynamical parameters of vegetation change with the growth of plant influence energy, water and CO2 exchanges between the surface and the atmosphere to realize the interaction between climate and vegetation. The annual variations of biomass, carbon dioxide, energy and water fluxes at the surface were simulated with the AVIM for temperate forest ecosystems in Northeastern China. The results compare well with the observations.