Global climate change usually involves simultaneous and continuous changes under different environmental conditions.However,it is very difficult and expensive to explore those climate change in manipulative experiments.Applying models can help us to understand the responses of ecosystem structure and function to global climate change.To explore the effects of climate change on carbon processes in grassland and cropland on the Loess Plateau,the Terrestrial Ecosystem (TECO)model was applied to identify patterns of ecosystem carbon processes in response to changes in CO_2concentration,temperature,and precipitation.The results showed that net primary production(NPP)and heterotrophic respiration(Rh)increased with temperature up to+4℃ and then declined,except that the highest Rh in cropland ecosystem was at 0 ℃ (ambient conditions). Net ecosystem exchange(NEE)showed the opposite trend with the lowest value at+4℃,and the highest C sequestration was at+4℃in both systems.Changes in precipitation and CO_2concentration affected the responses of NPP,Rh,and NEE to temperature change.The NPP,Rh,and NEE became more sensitive to temperature change with increased precipitation.Changes in precipitation affected the turning points of temperature responses for NPP,Rh,and NEE in the grassland ecosystem,but not in the cropland ecosystem.With increased CO_2concentration,the patterns of NPP,Rh,and NEE became flatter when temperature change was greater than +4 ℃.The interaction between increased precipitation and warming had the highest relative strength in terms of effects on NPP,Rh,and NEE,with values of 51.0%and 30.0%,51.3%and 16.6%, and-46.1%and-28.9%in the grassland and cropland ecosystem,respectively.The interaction between increased precipitation and increased CO_2concentration had the smallest relative strength in terms of effects on NPP,Rh,and NEE,with values of 2.4%and 7.5%,3.7%and 3.4%,and 8.1%and-9.0%,in the grassland and cropland ecosystems,respectively.Three-factor interactions were not significant for these ecosystems. Our results suggest that carbon dynamics are less sensitive in the cropland ecosystem than in the grassland ecosystem to interactions among climatic factors under climate change.