【摘要】 植被类型及其生长状况被认为是指示气候及其变化的重要因子,历来受生态学及气候研究重视,而以植被带随气候暖化向高海拔、高纬度地区的迁移为视角的研究则相对较少。本研究以指示植被带生长状况的归一化植被指数(AVHRR/GIMMS-NDVI)为分析手段,选取在气候变化中较为敏感的青藏高原为研究区,分析了1981–2015年35年间其植被带生长状况的时空差异,并与其对应的87个气象站点及同化数据的气温、降水气象资料以及经济统计数据等进行对比,以此来分析植被带对气候变化及人类活动影响的响应。结果显示:1)整个青藏高原在最近35年植被带生长状况总体上好转,这与气温及降水的增长趋势基本一致,但以高原为整体的研究在原因解释上较为困难。由于高原内部区域间差异很大,以不同的分区来研究植被带变化对气候及人为影响的响应无论在空间变化差异还是在原因解释方面均取得了较好的效果。2)在高原中部及其西南部的高海拔地区,植被带出现了普遍的增长,暖湿化的气候趋势是其主要原因。即气候暖化使得高海拔地区严寒的植被生长环境改善,林线上升,植被带扩展,NDVI增加。3)在高原东北部、东部边缘区及其东南部海拔相对较低、气候环境相对较好的地区其植被带普遍出现了退化趋势,与缓慢的气候变化相比较,人口增加等人为干扰因素的增强是其主要原因。即气候变化使得一些地区适宜于人类游牧和定居,人口迁入,城市化发展,当对植被带的影响超过了其承受能力时则出现逆转现象,植被带退化,NDVI减少。更多还原

【Abstract】 The types and growth statuses of vegetation are considered critical indicators that reflect climate regimes and have received much attention in ecology and climatology. However, studies focusing on climate warming influencing vegetation replacement toward high altitudes and latitudes, from the perspective of the redistribution of vegetation zones, are scarce.This study used AVHRR/GIMMS-NDVI as the indicator to represent the growth status of vegetation zones and chose the Qinghai-Tibetan Plateau(QTP) as the study area, because of its high sensitivity to climate change. The spatiotemporal dynamics of vegetation in the last 35 years, during 1981–2015, were analyzed. Additionally, the responses of vegetation to climate change and human activities were examined by analyzing the relationship between vegetation and climate/anthropogenic influences, using the temperature and precipitation data from 87 metrological stations, assimilated meteorological data, and economic statistical data on the QTP. The results show that ⅰ) on the whole, the growth status has been improving during the past 35 years. This trend was consistent with that of the temperature and precipitation data.However, it is difficult to explain the reasons behind the changes, when taking the QTP as a whole. By dividing the QTP into different sub-regions, from different zoning schemes, the spatiotemporal characteristics are clearly depicted and causes are reasonably explained. ⅱ) The vegetation in the middle and southwestern QTP, with high altitudes, was improving and the warm-humid climate trend was the main reason for this. That is, the frigid climatic conditions at high altitudes have been alleviated with global warming. With the treeline/timberline being lifted and vegetation zones expanding, the NDVI correspondingly increased. ⅲ) The degenerated regions are mainly in the northern and eastern QTP, which have high population/livestock densities. The slowly changing climate regime and anthropogenic influences, e.g., the rapid growth of livestock and population(urbanization), are the main reasons for the vegetation degradation.更多还原