全球2℃温升背景下青藏高原植被对气候变化的响应

Vegetation over the Qinghai-Xizang Plateau in Response to Climate Change with a 2 ℃ Global Warming

《巴黎协定》提出全球暖化程度在21世纪末相对工业革命前控制在2℃以内的目标。青藏高原高寒植被对全球变暖非常敏感,在2℃温升这个边界增温条件下研究高原植被对气候变化的响应关系到高原生态安全问题,有重大现实意义。本文基于CMIP5多模式模拟预测结果研究了高原植被对2℃温升的响应,并探讨了高原植被对于气候因子变化的敏感性,得到主要结论如下:在全球2℃温升背景下,高原植被叶面积指数(Leaf Area Index, LAI)较历史参考期显著增加,高原变绿,其中高原中部LAI和植被碳存储增加最为显著,三江源是植被LAI增加较快的区域。增温后裸地面积迅速减少,植被覆盖率总体增加,大部分地区草地呈增加趋势,森林减少趋势变缓,说明在2℃温升期高原植被有所改善。在全球2℃温升背景下,高原植被覆盖率表现出对温度和降水率等气候因子更强的依赖性和敏感性,在增暖环境中,气温仍是影响高原植被生态系统变化的主控因子。

Global warming has brought about a series of economic and environmental problems, seriously threatening the survival and development of human beings. The Paris agreement calls for limiting global warming to 2 ℃ for industrialization by the end of the century. Based on model simulations from CMIP5 in RCP8. 5, vegetation leaf area index(LAI) over the Qinghai-Xizang Plateau(QXP), vegetation carbon storage(NPP), the dominating land cover fraction and natural vegetation types in response to the warming climate are investigated. The main conclusions are as follows: LAI significantly increases under 2 ℃ warming, the QXP becomes green. NPP also increased significantly. Three river source regions have the most rapid growth rate, indicating that the carbon storage capacity of vegetation on the plateau is increasing. The bare soil decreases rapidly, while the grassland slowly increases and expands;The declined forest fraction is stable during 2 ℃ warming period. The overall vegetation coverage of the plateau increased and the vegetation covered area increases. Temperature is the main controlling factor affecting the change of the plateau vegetation ecosystem. In the context of global warming, vegetation has a better correlation with changes in temperature and precipitation, indicating that vegetation growth is more dependent on climate factors, and vegetation growth may be more sensitive to climate change.