Assessment of the nitrogen （N） balance and its long-term trend is necessary for management practices because of the negative environmental effects caused by an imbalance of reactive N in grassland ecosystems. In thi...Assessment of the nitrogen （N） balance and its long-term trend is necessary for management practices because of the negative environmental effects caused by an imbalance of reactive N in grassland ecosystems. In this study, we designed a module for the IAP-N （Improving Anthropogenic Practices of managing reactive Nitrogen） model to enable it to assess the N budget of regional grasslands. The module was developed to quantify the individual components of the N inputs and outputs for grassland ecosystems using livestock and human populations, grassland area, and fossil-energy consumption data as the model inputs. In this paper, the estimation approaches for individual components of N budget, data acquisition, and parameter selection are described in detail. The model was applied to assess the N budget of Inner Mongolia in 2006 at the county scale. The simulation results show that the most important pathway of N outputs from the grassland was livestock intake. The N output from livestock intake was especially large in the middle of Inner Mongolia. Biological fixation, atmospheric deposition, and livestock excreta deposition were comparably important for the N inputs into the grassland. The N budget for Inner Mongolia grassland in 2006 was -1.7×10 8 ±0.6×10 8 kg. The case study for Inner Mongolia shows that the new grassland module for the IAP-N model can capture the characteristics of the N budget in a semiarid grassland.展开更多
基金supported by the Ministry of Science and Technology of the People's Republic of China (Grant No 2010CB951801)the National Natural Science Foundation of China (Grant Nos 41021004 and 41075090)
文摘Assessment of the nitrogen （N） balance and its long-term trend is necessary for management practices because of the negative environmental effects caused by an imbalance of reactive N in grassland ecosystems. In this study, we designed a module for the IAP-N （Improving Anthropogenic Practices of managing reactive Nitrogen） model to enable it to assess the N budget of regional grasslands. The module was developed to quantify the individual components of the N inputs and outputs for grassland ecosystems using livestock and human populations, grassland area, and fossil-energy consumption data as the model inputs. In this paper, the estimation approaches for individual components of N budget, data acquisition, and parameter selection are described in detail. The model was applied to assess the N budget of Inner Mongolia in 2006 at the county scale. The simulation results show that the most important pathway of N outputs from the grassland was livestock intake. The N output from livestock intake was especially large in the middle of Inner Mongolia. Biological fixation, atmospheric deposition, and livestock excreta deposition were comparably important for the N inputs into the grassland. The N budget for Inner Mongolia grassland in 2006 was -1.7×10 8 ±0.6×10 8 kg. The case study for Inner Mongolia shows that the new grassland module for the IAP-N model can capture the characteristics of the N budget in a semiarid grassland.
