贺兰山植物物种资源构成的垂直分异

VERTICAL DIFFERENTIATION OF PLANT SPECIES COMPOSITION IN EAST SLOPE OF THE HELAN MOUNTAIN

该文通过建立物种资源数据库 ,分析了贺兰山东坡不同高程段中植物物种资源的构成特征 ,结果表明 :①贺兰山的植物物种多样性有随海拔升高先增加 ,随后又减少的变化趋势。海拔 1 4 0 0m～ 2 2 0 0m是植物物种集中分布的地段 ,海拔 1 80 0m～ 2 0 0 0m高程段内的的物种丰富度最大。②地理成分多样性随海拔高度增加而减少。③海拔 1 2 0 0m以下地段和海拔 30 0 0m以上地段的物种组成与其它各高程段的物种组成相似性较低。④植物物种资源构成特征的垂直分异是其现代生境特征和地史变化共同作用于植物区系的结果。

Based on a database of plant resources, species richness and species composition at different altitude, as well as vertical differentiation of vegetation in the east slope of Helan Mountain, which is divided into different altitudinal belts by every 200 meters, have been systemically analyzed in this paper. The results show: 1) Maximum of the species richness index is found in the belts between 1400 and 2200m in elevation, and for those belts going up to the top or down to the foot, their values decrease accordingly. 2) With the altitude ascending, the geographical element diversity index of the flora descends. 3) The Sorensen similarity indexes of species composition, between the belts of basal zone——lower than 1200m a.s.l., as well as those of alpine zone——higher than 3000m a.s.l., and others, are relatively low. 4) It can be concluded that vertical differentiation of vegetation species depend both on the present ecological factors and on the environmental changes related to historically geological events.