陆地生态系统对气候变化的响应及其脆弱性评价研究是当前全球变化领域的重要内容之一。该研究在生态系统过程模型的基础上,耦合了潜在植被对气候变化的动态响应,模拟气候变化对潜在植被分布格局和生态系统主要功能的影响,以潜在植被的变化次数和变化方向定义植被分布对气候变化的敏感性和适应性,以生态系统功能特征量的年际变率及其变化趋势定义生态系统功能对气候变化的敏感性和适应性,进而对生态系统的脆弱性进行定量评价,分析不同气候条件下我国陆地生态系统的脆弱性分布格局及其区域特点。结果表明,我国自然生态系统气候脆弱性的总体特点为南低北高、东低西高,气候变化将会增加系统的脆弱性。采用政府间气候变化委员会排放情景特别报告国内和区域资源情景,即IPCC-SRES-A2气候情景进行的预测模拟表明,到21世纪末我国不脆弱的生态系统比例将减少22%左右,高度脆弱和极度脆弱的生态系统所占的比例较当前气候条件下分别减少1.3%和0.4%。气候变化对我国陆地生态系统的脆弱性分布格局影响不大。不同气候条件下,高度脆弱和极度脆弱的自然生态系统主要分布在我国内蒙古、东北和西北等地区的生态过渡带上及荒漠-草地生态系统中。总体而言,华南及西南大部分地区的生态系统脆弱性将随气候变化而有所增加,而华北及东北地区则有所减小。

Aims Assessment of the sensitivity and vulnerability of terrestrial ecosystem to climate change is one of the most important aspects of global change research. Our objective was to develop a new approach to assessing the vulnerability of terrestrial ecosystem using a process-based ecosystem model.

Methods We developed a new quantitative approach to assess vulnerability of terrestrial ecosystems based on an ecosystem process model with two aspects: vegetation changes and ecosystem function changes. In accordance with the definition of vulnerability used by the Intergovernmental Panel on Climate Change (IPCC), we used change times and changing direction of vegetation as key indicators of sensitivity and adaptation of vegetation responses to climate change. We also used the function's annual variability and its trend as indicators of sensitivity and adaptation of ecosystem functions response to climate change, respectively. Based on these indicators, the integrated vulnerability was determined, including assessment under the contemporary climate condition and future climate change scenarios.

Important findings The more vulnerable ecosystems were found in the north and west areas of China, with less vulnerable ecosystems mostly in the south and east. The vulnerability of ecosystems would increase with climate change, but the pattern of vulnerability would be little changed by the end of this century, depending on the scenarios. The percentage of non-vulnerable ecosystems would be reduced by about 22%, and the highly and exceedingly vulnerable ecosystems would be reduced by about 1.3% and 0.4%, respectively. Most highly vulnerable ecosystems are distributed in northwestern China, Inner Mongolia, south of the Tibet Plateau and some areas of northern and northeastern China, both under contemporary climate condition and the future climate change scenarios, and they were mainly scattered in transition eco-zones and grassland-desert ecosystems in northwestern China. When investigated regionally, the vulnerability would increase in southern, central, northwestern and southwestern China, but vulnerability would decrease in northern and northeastern China and Inner Mongolia of China.