气候变暖背景下近30a北半球植被变化研究综述

Vegetation Variation in the North Hemisphere under Climate Warming in the Last 30 Years

归一化植被指数（NDVI）目前广泛应用于全球和区域尺度植被变化研究,成为揭示气候变化的重要指标。基于NDVI变化以及NDVI提取的植被物候变化2个方面（植被生长季开始时间SOG,植被生长季结束时间EOG）,对近30 a气候变暖背景下北半球植被变化的有关研究结论进行回顾总结。结果显示：①近30 a北半球植被生长季NDVI整体呈增加趋势,森林植被NDVI增长速率大于其他植被类型;20世纪90年代NDVI增加趋势较80年代显著,从21世纪初开始,出现NDVI增长速率减缓现象;②近30 a北半球SOG整体呈提前趋势,近10 a SOG提前趋势减缓;欧亚地区SOG提前趋势可能较北美显著,非洲植被物候变化规律不清晰;北半球植被物候变化表现出明显的纬度地带性,55°～65°N纬度带SOG提前趋势与45°～55°N纬度带EOG推迟趋势相对显著;③除森林退化严重外,近30 a青藏高原植被整体上以增加为主,NDVI增长趋势北部显著,中部和东部微弱,南部呈下降趋势;高原东部和藏北SOG提前趋势显著,而中部、西部和西南部有推迟现象。

The monitoring of Normalized Difference Vegetation Index（ NDVI） is widely used nowadays in the research on vegetation variation at both regional and global scales,which becomes as an important mean to reveal climate change. The important progresses in vegetation variation in the Northern Hemisphere under global warming in recent 30 years were systematically reviewed by focusing on the NDVI variation and the vegetation phenology extracted from NDVI（ SOG： start of growing season; and EOG： end of growing Season）. Results are as follows： ① A positive trend of NDVI occurred in the Northern Hemisphere in recent 30 years,the increase trend of forest NDVI was more obvious than that of other vegetation types,the increase trend of NDVI was more significant in the end-1990 s than that in the 1980 s,but it began to weaken from the beginning of the 21 st century; ② There was an advanced trend of SOG in the Northern Hemisphere in recent 30 years,but such trend was slowed down during the first decade of this century. The advanced trend of SOG in the Eurasian region was more significant than that in North America,but the vegetation phenology change in Africa was not clear. The significant advanced trend of SOG was obvious in the latitudinal zone of 55°- 65°N,and there was a significant delay trend of EOG in the latitudinal zone of 45°- 55°N; ③ Despite of the serious forest degeneration,the vegetation cover became well in the Qinghai-Tibetan Plateau in recent 30 years,the NDVI was in a positive trend in the north,a slight increase trend in the center and east,and a decrease trend in the south. The advanced trend of SOG was also notable in the eastern and northern parts of the Qinghai-Tibetan Plateau.