锡林河流域草原植物群落多样性沿海拔梯度变化特征

Variation of Steppe Plant Community Diversity along with Altitudinal Gradient in the Xilin River Basin

以锡林河流域草地植被为研究对象,采用物种重要值,α、β多样性指数对流域植物群落多样性沿海拔梯度分布特征进行研究。结果表明:在各海拔梯度内羊草均占优势地位。随着海拔梯度的升高,α多样性指数均呈现先降低后升高的变化趋势;在影响Simpson多样性指数的程度上,丰富度指数高于均匀度指数。随着海拔梯度的升高,β多样性指数具有先降低后升高再降低的变化趋势。在海拔梯度1 200 m^1 300 m与1 300 m^1 400 m之间群落物种相似度较高,物种更替速率较慢;在海拔梯度1 100 m^1 200 m与1 200 m^1 300 m之间群落物种组成差异性较大,物种更替速率较快。

Based on the grassland vegetation in the Xilin River Basin,the species importance values,andα,β diversity index were used to study the distribution of plant community diversity along the altitudinal gradient. At each altitude gradient,Leymus chinensis was dominated. With the increase of the altitude gradient,α diversity index trended to decrease first and then increase. To the affected extent of Simpson diversity index,the richness index was higher than the evenness index. With the increase of the elevation gradient,β diversity index trended to decrease first and then increase,then decrease again. The species had high similarity between1 200 m and 1 300 m,and between 1 300 m and 1 400 m altitudinal gradient. The species replacement rate was slow. At the altitude gradient of 1 100 m ~ 1 200 m and 1 200 m ~ 1 300 m,the species composition had distinct difference,and the species replacement rate was rapid.