水热积指数的估算及其在中国植被与气候关系研究中的应用

试图利用大气年平均气温、年降水量、可能蒸散和土壤水分平衡之间的关系建立一个水热积指数,并应用年平均气温、年土壤水分盈亏值和水热积指数三个气候变量来限定植物群落组合,构成一个圆形的生命-气候图式。根据全国689个标准气象台站的气候资料,计算了中国8个植被地带和26个亚地带的年平均气温、年土壤水分盈亏和水热积指数,绘制了各气候指标在中国的分布图及散点图,较好表现了中国各植被类型与气候指标的关系和格局,包括寒温带针叶林、冷温带针阔叶混交林、暖温带落叶阔叶林、亚热带常绿阔叶林、热带雨林和季雨林、温带草原、温带荒漠、青藏高原高寒植被,并得到了中国各植被地带的气候指标范围及界限。通过分析可以看出,年平均气温的等值线较好地反映了中国大陆的热量梯度,经度和纬度方向的区分均较明显;年土壤水分盈亏曲线的等值线则比较零乱;综合了热量和水分差异的水热积指数等值线与热量梯度和水分梯度均有一定的对应性,与植被类型的对应也较好。这是在宏观尺度上进行的植被与气候关系研究的一种尝试。

ESTIMATION OF WATER AND THERMAL PRODUCT INDEX AND ITS APPLICATION TO THE STUDY OF VEGETATION-CLIMATE INTERACTION IN CHINA

A water and thermal product index was in attempt to be established according to the relations among annual average temperature, annual precipitation, potential evapotranspiration and soil water balance. The plant community groups were constrainted to form a circular life-climate diagram using three climatic indices, annual average temperature, annual soil water surplus and deficit, and water and thermal product index. Based on the records of 689 meteorological stations of China, the annual average temperature, soil water surplus and deficit, water and thermal product index of 8 vegetation zones and 26 subzones were calculated. The vegetation types included cold-temperate (boreal) coniferous forest, cool-temperate mixed coniferous-broadleaved forest, warm-temperate deciduous broadleaved rain forest, subtropical evergreen broadleaved forest, tropical forest and monsoon rain forest, temperate steppe, temperate desert and Tibetan high-cold plateau alpine vegetation . Additionally, distributional and scatter graphs of every climatic index were drawn. All of these highlighted well the relationship and pattern between vegetation and climate in China. The isopleth of annual average temperature relatively reflected the thermal gradient in China. The differences in latitude and longitude were significant. The isopleth of soil water surplus and deficit was scattered. The isopleth of water and thermal product index not only showed better relation to thermal and water gradients but also to vegetation types. The study was an attempt of under standing the vegetation-climate interaction at a large scale which merits more understanding of its mechanism, such as the interaction and feedback between vegetation and climate, plant population, and soil characteristics, etc. to further improve this method.