中国生态过渡带分布的空间识别及情景模拟

在全球变化及其生态环境效应研究中,如何对生态过渡带的空间分布格局及变化情景进行空间定量识别和模拟分析,对揭示气候变化和人类活动对全球变化的响应及反馈具有指示性意义。在对HLZ模型进行修正和拓展的基础上,建立了生态过渡带类型的空间识别方法。并基于1981—2010年的全国782个气候观测站点数据,在实现全国生态过渡带类型及分布的空间识别基础上,结合3种气候情景数据CMIP5 RCP 2.6、RCP 4.5和RCP 8.5,实现了T0（1981—2010年）、T1（2011—2040年）、T2（2041—2070年）和T3（2071—2100年）4个时段内全国生态过渡带的空间分布格局及其未来情景模拟。另外,引入平均中心空间分析模型,对全国生态过渡带平均中心的时空偏移趋势进行了定量分析。结果显示：在T0~T3时段内,全国共出现41种生态过渡带类型,约占全国陆地面积的18%;冷温带草原/湿润森林与暖温带干旱森林过渡带（564238.5 km²）、冷温带湿润森林与暖温带干旱/湿润森林过渡带（566549.75 m²）、北方湿润/潮湿森林与冷温带湿润森林过渡带（525750.25 km²）是最主要的3种生态过渡带类型。面积占到全国生态过渡带总面积的35%;2010—2100年期间的冷温带荒漠灌丛与暖温带荒漠灌丛/有刺草原过渡带的增加速度最快,在3种情景RCP 2.6、RCP 4.5和RCP 8.5下,其面积将分别增加3604.2 km²/10a、10063.1 km²/10a和17242 km²/10a;寒冷型生态过渡带类型总体上呈向暖湿型过渡带类型增加的趋势;北方潮湿森林与冷温带湿润/潮湿森林过渡带的平均中心偏移幅度最大,在4个时段内整体向东北方向偏移,其偏移幅度将超过150 km。另外,随着气温的逐渐上升和降水量的增加,中国北方的生态过渡带整体呈向北偏移趋势,南方生态过渡带则逐渐减少且平均中心呈现逐渐向高海拔地区退缩的趋势,气候变化对青藏高原区生态过渡带时空格局的影响日益显著。

Spatial identification and scenario simulation of ecotone distribution in China

Explicitly identifying the ecotone distribution and scenario change is of important significance to understand the response of ecosystem to climatic change. In this paper, a spatial identification method was developed to analyze the ecotone distribution in terms of the improved Holdridge life zone(iHLZ) model. Based on the climatic observation data of 782 weather stations of China in the T0(1981-2010) period, and the climatic scenario data of IPCC CMIP5 RCP2.6, RCP4.5 and RCP8.5 in T1(2011-2040), T2(2041-2070) and T3(2071-2100),the ecotones distribution and scenarios in China were simulated in the four periods. Moreover,a spatial shift trend model of mean center was introduced to quantitatively calculate the shift direction and distance of each ecotone type during the periods from T0 to T3. The simulated results show that there are 41 ecotone types in China, accounting for 18% of the total land area of China. The ecotones of cold temperate grassland/humid forest and warm temperate arid forest(564238.5 km²), cold temperate humid forest and warm temperate arid/humid forest(566549.75 km²), and northern humid/humid forest and cold temperate humid forest(525750.25 km²) are the main ecotone types, accounting for 35% of the total area of ecotones in China. Between T0 and T3, the area in the ecotone of cold temperate desert shrub and warm temperate desert shrub/thorn steppe will increase at a rate of 4% per decade, which is up by3604.2, 10063.1 and 17242 km² per decade under the RCP2.6, RCP4.5 and RCP8.5 scenarios,respectively. The cold ecotones will transform to the warm humid ecotones in the future. The average shift distance of mean center in the ecotone of north wet forest and cold temperate desert shrub/thorn grassland will be generally larger than that of other ecotones, whose mean center will move to the northeast, and the shift distance will be more than 150 km between T0 and T3. In addition, with a gradual increase of temperature and precipitation, the ecotones in northern China will show a shifting northward trend, while the ecotones in southern China will decrease gradually, and their mean center move to the high-altitude areas. The effects of climate change on ecotones will show an increasing trend in China, especially in the QinghaiTibet Plateau.