东北地区植被分布全球气候变化区域响应

Response of Vegetation Distribution to Global Climate Change in Northeast China

根据东北地区生态气候环境和生物地理规律对Holdridge生命地带分类系统进行修正,将东北地区植被分为寒温带湿润森林、寒温带潮湿森林、温带湿润森林、暖温带湿润森林、温带半湿润森林草甸草原、温带半湿润草甸草原、温带半干旱典型草原、暖温带半湿润草甸草原和暖温带半干旱典型草原等9个生命地带并分析了其空间分布特征。运用大气环流模式分析东北地区由于温室气体增加导致的气候变化趋势。以此为基础评价东北地区植被分布的区域响应。全球气候变暖情景下,东北地区暖温带和温带范围明显扩大,而寒温带范围缩小甚至退出东北地区,植被分布界限显著北移;同时湿润区面积减少半湿润区和半干旱区扩大,导致森林面积缩小草原面积扩大。

In recent years, IPCC emphasizes the assessment of regional responses to global climate change, and tries to understand the climate change impacts on regional/global scales and to make mitigation adaptation. Northeast China in temperate monsoon climate is the vulnerable and sensitive area of climate change. The impact of global climate change on the vegetation in Northeast China is an important researching field. By using GCMs scenarios, the regional assessment of vegetation distribution response to climate change has been done. According to the characteristics of eco-climate and bio-geography in Northeast China, some index limits of Holdridge life zone classification system are modified. Based on bio-temperature (BT) and potential evapotrans-piration ratio (PER, determined by Thornthwaite model) , Northeast China climate are classified as 3 thermal zones, i.e. cold temperate zone ( BT < 6℃), temperate zone ( 6℃≤BT < 9.8℃ ) and warm temperate zone (BT ≥9. 8℃ ). And 4 humid types i. e. moist type (PER≤0. 75) , humid type (PER≤1), semi-humid type (1 < PER≤1.25) and semi-arid type (PER > 1.25 ). And then taking annual precipitation (P, mm) into account we divide Northeast China vegetation into 9 life zones, i. e. Cold temperate moist forests, Cold temperate humid forests , Temperate humid forests, Warm temperate humid forests, Temperate semi-humid forests/meadow, Temperate semi-humid meadow prairie, Temperate semi-arid prairie, Warm temperate semi-humid meadow prairie and Warm temperate semi-arid prairie. General Circulation Models ( GCMs) simulates climate warming scenarios induced by the anthropogenic Green-House Gases(GHGs) concentration increasing in atmosphere. For Northeast China, the analysis indicate that under CO2 concentration doubling annual mean temperature increase by 3℃ -4℃ and precipitation by 9% - 12% , but the potential evapotranspiration increase much more than precipitation increment because of temperature increasing. Thus regional scenario of climate change in Northeast China would be with a high possibility of warming and aridity. Response to the climate change, the eco-climatic environment and distribution of vegetation life zone may change greatly in Northeast China. The assessment of regional impacts on vegetation shows: 1) Under climate warming scenarios, the warm-temperate and temperate zones enlarge, but cool-temperate zone becomes small and even disappears in the northeast, which would result in the boundaries of vegetation life zones transferring northward obviously and 2 cold temperate life zones would move to a higher altitude or move out from this region; 2) At the same time, the humid area shrink, and semi-humid area and semi-arid area expend, which would make forest range shrink and grassland expand in Northeast China.