气候变化与人类活动对内蒙古东部草地净初级生产力的影响

内蒙古东部草地是该区域的主体生态系统类型，属于脆弱的生态系统，对气候和人类活动反应敏感。基于土地覆被数据和改进CACS模型，估算得到的草地NPP，分析2000-2015年内蒙古东部草地和NPP时空格局与年际动态。进而，定义相对退化指数（RDI），确定草地生产力变化过程中人类活动因素的贡献率，分析内蒙古东部地区2000-2015年RDI空间格局与年际动态。同时，分析16年间NPP和气候因子相关关系。结果表明：1）2000-2015年间，损失草地面积4743.80 km²，新增草地面积2705.57 km²。2）2000-2015年内蒙古东部地区草地植被平均NPP位于166.56-248.14 gC m^-2 a^-1之间，NPP在波动中呈现明显的上升趋势（3.65 gC m^-2 a^-1/a，R²=0.47）。3）2000-2015年RDI在16.64%-30.54%之间波动，RDI值呈缓慢下降趋势，表明人类活动对草地植被净初级生产力的干扰程度在下降。4）草地NPP变化主要是因为草地本身生产力下降。整体来看相关草地保护工作取得了阶段性进展，草地生境质量得到有效缓解，草地生态环境得到转变。

Impacts of climate change and human activities on net primary productivity of grassland in the eastern Inner Mongolia

Grassland is the main ecosystem type in the eastern Inner Mongolia, which belongs to the fragile ecosystem and is sensitive to climate and human activities. Based on land cover data and the improved CACS model, the grassland NPP(net primary productivity) was estimated, and the spati-temporal dynamics of grassland and NPP in the eastern Inner Mongolia from 2000 to 2015 were analyzed. Furthermore, the relative degradation index (RDI) was defined to determine the contribution rate of human activities in the process of grassland productivity change, and the spatial pattern and interannual dynamics of RDI in the eastern Inner Mongolia from 2000 to 2015 were analyzed. At the same time, the correlation between NPP and climatic factors during the past 16 years was inverstigated. Results showed that: 1) during 2000-2015, the loss and increase of grassland area was 4743.80 km² and 2705.57 km², respectively. 2) From 2000 to 2015, the average NPP of grassland in the eastern Inner Mongolia ranged from 166.56 to 248.14 gC m^-2 a^-1. NPP showed an obvious upward trend in fluctuation (3.65 gC m^-2 a^-1/a, R²=0.47). 3) From 2000 to 2015, RDI fluctuated between 16.64% and 30.54%, and the RDI value showed a slow downward trend, indicating that the influence of human activities on grassland-NPP was decreasing. 4) The main reason of NPP change is the decrease of grassland productivity. Overall, the grassland protection work had made phased progress, and grassland habitat quality and ecological environment had been effectively improved.