青藏高原是全球平均海拔最高的自然地理单元.近几十年乃至上百年来,在气候变化和人类活动双重影响下,青藏高原生态系统的结构和功能以及重要物种的种群数量和结构均发生了深刻的变化.近几十年的研究表明:青藏高原植被返青期提前,生长期延长,覆盖度和生产力增加,碳汇功能增强,青藏高原植被总体趋于向好,局部变差.气候变化是高原生态系统变化的主控因子,气候变暖对青藏高原生态系统的影响是正面的,但这种影响仍存在时间和空间上的不平衡性,尤其是降水在时间和空间上的变化对干旱和半干旱地区植被产生较大影响,在干旱的年份叠加人类放牧活动等会导致这些区域,尤其是青藏高原西部地区植被产生严重的退化,但随着青藏高原生态安全屏障保护与建设工程的实施,高原生态系统退化的态势得到了进一步遏制,人类对高原特有珍稀植物资源,如虫草、雪莲和胡黄连的过度采收以及对野牦牛、藏羚羊和藏野驴的盗猎等现象得到近一步缓解,近期高原的野牦牛、藏羚羊和藏野驴的种群数量得到恢复.青藏高原的隆起不仅对本区而且对其毗邻地区的气候与环境都产生着深刻的影响,其生态系统对全球变化的响应与影响研究具有特殊重要的地位,今后迫切需要加强生态系统结构和功能变化的地面监测和遥感技术的应用,加大大型生态保护工程建设的实施力度,整体提高高原地区应对全球变化的能力. 更多

The Tibetan Plateau is the highest physiographic unit regarding average elevation globally. In recent history, the ecosystem structure and function of the Tibetan Plateau, and population size and composition of the dominant species have shown profound changes due to the dual effect of climatic change and human activities. Studies during recent decades on this ecosystem showed that the green-up date of vegetation has advanced resulting in an extended growing period. Generally, the vegetation on the Plateau has improved, but with some local areas becoming degraded. Climatic warming has been a key factor responsible for the positive ecosystem change; however, this effect has been varied, especially the spatiotemporal changes of precipitation, which resulted in large changes of vegetation growth in arid and semi-arid regions. In drought years, the dual effect of climatic change and human activities caused the severe degradation of grasslands, particularly in the western region. However, with the implementation of a constructive project to protect the security of the ecological barrier on the Tibetan Plateau, the degradation of alpine ecosystems has been reduced, and the overexploitation of rare plant resources (e.g., Cordyceps spp., Saussurea spp., Picrorhiza scrophulariiflora) and poaching of wild animals (e.g., yak, Tibetan antelope, and Tibetan wild ass) have decreased, and their populations are recovering. The uplift of the Tibetan Plateau has affected its climate and environment and those of the adjacent areas. Future studies should consider the impact of global change on the Tibetan Plateau, and monitor the changes in ecosystem structure and function through field investigations and the application of remote sensing technology. Further implementation of large-scale ecological engineering to improve the ability of local residents to respond to global change on the Tibetan Plateau is necessary.