The DLEM is a highly integrated land ecosystem model which couples major biogeochemical cycles, hydrological cycle, and vegetation dynamics to make daily, spatially-explicit estimates of water, carbon (CO2, CH4) and nitrogen fluxes (N2O) and pool sizes (C, N and water) in terrestrial ecosystems. DLEM builds on the experience and heritage of the existing Terrestrial Ecosystem Model (Raichet al. 1991; Melilloet al. 1993; McGuire et al. 1992, 2001; Tianet al. 1998, 1999, 2000, 2003; 2005, Felzeret al. 2004, 2005) and Biome-BGC (Running and Hunt 1993; Thornton, P.E. 1998, 2002). DLEM includes five core components (Fig. a): 1) biophysics, 2) plant physiology, 3) soil biogeochemistry, 4) dynamic vegetation, and 5) land use and management. DLEM also integrates algorithms of N2O emission from DNDC (Li and Aber2000) and CH4emission from other previous studies (Huang et al. 1998,2005; Zhuanget al. 2004). The biophysical component includes the instantaneous exchanges of energy, water, and momentum with the atmosphere. Plant physiology component simulates major physiologic processes such as photosynthesis, respiration, allocation among various parts (root, stem and leave), nitrogen uptake, transpiration, phenology, etc. Soil biogeochemistry simulates mineralization, nitrification/denitrification, decomposition and fermentation.The dynamic vegetation component in DLEM simulates two kinds of processes: the biogeography redistribution when climate change, and the plant competition and succession during vegetation recovery after disturbances.