借助广义线性模型（generalized linear models，GLM），拟合了混沟森林植被乔、灌、草各层及群落总体的Shannon-Wiener指数与环境因子问的关系，并通过SФrenson指数研究了海拔梯度上相邻森林群落类型物种组成的相似性，结果显示：（1）土壤pH值和海拔高度是对物种Shannon-Wiener指数影响最广泛的环境因子，湿度指数对混沟地区物种多样性影响不大。坡向对乔木层Shannon-Wiener指数的影响比较大，对灌木层和草本层a多样性无明显作用，在中等pH值和半阴／半阳坡乔木层Shannon-Wiener指数最小；灌木层Shannon—Wiener指数随海拔的升高呈下降趋势；草本层Shannon—Wiener指数没有表现出特定的变化规律；群落总体Shannon—Wiener指数主要受土壤pH值影响，随着pH值的增加呈上升趋势；（2）乔、灌、草各层以及群落总体的SФrenson指数在海拔梯度上的变化规律大致相同，都是在中等海拔处较低，低海拔和高海拔处各有一个峰值，海拔1000～1500m段可能是混沟主要植被类型的过渡带。
The species richness of herb layer was investigated among 43 plots of forest vegetation in the eastern Zhongtiao Mountain, in southern Shanxi Province, China. The forest vegetation was divided into two major vegetation types such as the deciduous forest and the coniferous forest by the two-way indicator species analysis （TWINSPAN）. The species richness of herb layer was fitted in the topographic and soil feature factors, as well as the topographic relative moisture index （TRMI） by the generalized linear models （GLM）. The results showed that canopy cover and altitude were the most significant environmental factors. Soil pH value and soil nutrients index such as total N, organic matter content had no significant influence. The effect of environment factors on species richness of herb layer had significant difference in vegetation types. For the broad-leaved forest, litter depth and TRMI were the important environment factors. For the coniferous forest, soil clay content was another important environment factor. The range of environmental gradient such as altitude may contribute to the difference.
