基于DNDC模型分析氮添加对内蒙古草甸和荒漠草地碳动态的影响OA北大核心CSTPCD

[Objective]The aims of this study are to determine the changes of plant biomass carbon and soil organic carbon in different grassland types in Inner Mongolia under the background of nitrogen deposition,and to investigate the applicability of the DNDC model to simulate the carbon dynamics of grasslands in this region,which is of great significance for mitigating climate change and achieving the goal of the'dual-carbon strategy'.[Methods]The response of Inner Mongolian meadows and desert grasslands to nitrogen deposition was investigated and verified by simulation using the DNDC model.The effects of nitrogen addition on carbon pools in different grasslands were analyzed by setting different gradients of nitrogen addition[0,5,10,15,20,25,30 gN/(m2·a)],and the differences in their simulations by the DNDC model were evaluated.[Results](1)Compared with the control,nitrogen addition promoted aboveground biomass carbon in meadow grassland and desert grassland,with an average increase of 72.68％and 66.52％,respectively,and the belowground biomass C of meadow grassland reached the maximum under N5 treatment(240.93 gC/kg),while the increase of the desert grassland was the largest under the N4 treatment(129.67 gC/kg).(2)Compared with the control,nitrogen addition did not significantly affect belowground biomass carbon of the two grasslands,with a different response from that of above-ground biomass carbon.Nitrogen addition had no significant effect on the below-ground biomass carbon of the two types of grassland relative to the control group,and the response was different from that of the aboveground biomass carbon,but on the whole,the below-ground carbon showed the order:meadow grassland＞desert grassland.(3)The effect of nitrogen addition on the soil organic carbon content of the two types of grassland was not significant,and there was no significant difference between the different treatments of nitrogen addition,and on the whole,soil organic carbon content of meadow grassland was higher than that of desert grassland,(4)The DNDC model was able to simulate the above-ground and below-ground biomass carbon and soil organic carbon of the meadow grassland and desert grassland in the study area better,and the simulated values of the model were basically consistent with the measured values,the coefficients of determination(R2)were 0.942 6,0.756 8,0.825 7,0.523 8,and 0.909 9,respectively,0.955 2,0.861 0,0.732 4,and the model efficiency coefficients E were 0.834 5,0.674 8,0.799 4,0.428 8 and 0.873 1,0.926 5,0.716 8,0.538 1,respectively.The simulation effect of the points was good on the whole,but for the simulation of the biomass carbon,the degree of agreement was better,and the simulation of the desert grassland was better than that of the meadow grassland.[Conclusion]Overall,nitrogen addition promotes the carbon sequestration capacity of different arid types of grasslands,and the DNDC model can better reflect the effects of nitrogen deposition on the two types of grasslands in Inner Mongolia,so the model can be used to simulate the biomass carbon and soil organic carbon of grassland ecosystems in Inner Mongolia.