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The process-oriented model Forest-DNDC describing biogeochemical cycling of C and N and GHGs (greenhouse gases) fluxes (CO2, NO and N2O) in forest ecosystems was applied to simulate carbon sequestration and GHGs emissions in Abies fabric forest of the Gongga Mountains at southeastern edge of the Tibetan Plateau. The results indicated that the simulated gross primary production (GPP) of Abies fabric forest was strongly affected by temperature. The annual total GPP was 24,245.3 kg C ha−1 yr−1 for 2005 and 26,318.8 kg C ha−1 yr−1 for 2006, respectively. The annual total net primary production (NPP) was 5,935.5 and 4,882.2 kg C ha−1 yr−1 for 2005 and 2006, and the annual total net ecosystem production (NEP) was 4,815.4 and 3,512.8 kg C ha−1 yr−1 for 2005 and 2006, respectively. The simulated seasonal variation in CO2 emissions generally followed the seasonal variations in temperature and precipitation. The annual total CO2 emissions were 3,109.0 and 4,821.0 kg C ha−1 yr−1 for 2005 and 2006, the simulated annual total N2O emissions from forest soil were 1.47 and 1.36 kg N ha−1 yr−1 for 2005 and 2006, and the annual total NO emissions were 0.09 and 0.12 kg N ha−1 yr−1 for 2005 and 2006, respectively.

Canpopy interception, evapotranspiration, runoff yield and concentration constitute primary hydrologic processes, which mathematic modeling contributes an important way to study hydrologic regularity. Jialingjiang hilly areas is an important ecological barriers and economic zone of Yangtyz river. In this paper, a tipical small watershed-Lizixi basin is selected to simulate main hydrology processes of Jialingjiang hilly small watershed. Results of model show that the model uncertainty factor meets the precision requirements of B and relative error is below 15%, which indicates that the model reflects the actual hydrologic process basically and the model is effective.

Based on the studies to the erosion mechanics of slope and rill, the basic problems and computation methods are discussed on the erosion simulation. Some new modes in computation of channel deposition and restarting are derived. The key links and impact factors to watershed erosion and sediment transportation are analyzed. A mathematic model has been built to simulate small watershed erosion and sediment yield. The model was verified by Lizixi basin and got good results.