We have developed a highly integrated land ecosystem model called Dynamic Land Ecosystem Model (DLEM), 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 and N) in terrestrial ecosystems. DLEM builds on the experience and heritage of the existing Terrestrial Ecosystem Model (Raich et al. 1991; Melillo et al. 1993; McGuire et al. 1992, 2001; Tian et al. 1998, 1999, 2000, 2003; 2005, Felzer et al. 2004, 2005) and Biome-BGC (Running and Hunt 1993; Thornton, P.E. 1998, 2002, Mu et al. 2006). DLEM includes five core components: 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 Aber 2000) and CH4 emission from other previous studies (Huang et al. 1998,2005; Zhuang et al. 2004). 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. Like most DGVMs, DLEM builds on the concept of plant functional types (PFT) to describe vegetation distributions. The DLEM has also emphasized the modeling and simulation of managed ecosystems including agricultural ecosystems, plantation forests and pastures. We have used the DLEM to simulate the effects of climate variability and change, atmospheric CO2, tropospheric ozone, land-use change, nitrogen deposition, and disturbances (e.g., fire, harvest, hurricanes) on terrestrial carbon storage and fluxes in China and the United States. This model has been calibrated against various field data from the Chinese Ecological Research Network, LTER and AmeriFlux Network. The simulation results of the model have been compared with independent field data and satellite products. To assess the two-way response of terrestrial ecosystems to climate forcing and vice versa, DLEM is being coupled with regional climate model.