| 摘 要： |
Climate change and anthropogenic activities are altering grasslands on the Qinghai-Tibetan Plateau. This Review examines vegetation and soil changes, and the role of various drivers in affecting them. Grasslands on the Qinghai-Tibetan Plateau (QTP) foster biodiversity, store carbon, maintain productivity and support pastoral livelihoods. These systems are being altered by climate change and anthropogenic activities, but the relative importance of these drivers are still debated. This Review examines QTP grassland changes since the 1980s and discusses the impacts of global change on plant communities and soil properties. The normalized difference vegetation index (NDVI) (which can be used to track vegetation greenness) has generally increased since the 1980s, but with substantial spatial variability and some local decreases. Rising temperatures were key in driving the NDVI increases, but also likely exacerbated water deficiency in areas with little precipitation (<100 mm year(-1)), accounting for some of the spatial variability in trends. Intense livestock grazing negatively affects vegetation and soil when stocking rates are higher than grassland carrying capacity, causing grassland degradation. Degraded grassland can be effectively restored by management policies that minimize or exclude grazing and by adaptive management; these practices became important drivers of net primary production increases after 2000. However, better management of grasslands under a future of increasing temperatures and settlement requires a deeper understanding of the large-scale plant species composition shifts and the combined effects of climate change and anthropogenic activities. |
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