伊犁河谷山地植物群落物种多样性分布格局及环境解释

结合对新疆伊犁河两岸科古琴山南坡(河谷北坡)和乌孙山北坡(河谷南坡)94个样地的调查资料,采用DCCA(detrended canonical correspondence analysis)排序法,分析了物种多样性指数与环境因子之间的关系,运用广义可加模型拟合植物群落总体多样性指数对海拔梯度的响应曲线,探讨了伊犁河谷山地植物群落物种多样性的垂直分布格局。结果表明:在调查的94个样地中,共出现259种植物,其中,草本植物的种类极其丰富,多达235种,木本植物的种类极其有限;垂直结构完整的植物群落具有较高的多样性指数;河谷北坡植物群落物种多样性的分布格局受海拔、坡度、坡向以及土壤全氮、全钾、有机质、含水量等环境因子的影响较大,而在河谷南坡,物种多样性分布格局主要受坡度、海拔、有效磷含量和土壤含水量等环境因子的影响;在河谷北坡,植物群落的Patrick丰富度指数与Shannon-Wiener指数与海拔呈明显的双峰曲线关系,Simpson指数与Pielou均匀度指数呈不对称的单峰格局,而河谷南坡的物种多样性指数随海拔均呈双峰格局,尽管Patrick丰富度指数不甚明显。山地植物群落物种多样性的垂直分布格局是由海拔为主的多种环境因子综合作用的结果。

Distribution pattern and environmental interpretation of plant species diversity in the mountainous region of Ili River Valley,Xinjiang,China

Aims Our major objective was to reveal the distribution pattern of plant species diversity in the mountainous region of Ili River Valley, Xinjiang, China and explore how environmental gradients influenced the pattern. Methods Based on a survey of 94 sample plots in the study area, DCCA was performed to analyze the relationships between diversity indices and environmental gradients and GAM was employed to model the response curve of diversity indices to elevation. Important findings We recorded 259 plant species, including 235 herbaceous species; the species of woody plants were very limited. Communities with complex vertical structure had higher values of diversity. The distribution pattern of species diversity on the northern slope was affected by elevation, slope aspect, slope gradient, total nitrogen, total potassium, soil water content, organic matter, etc., and that on the southern slope was mainly affected by slope gradient, elevation, available phosphorus, soil water content, etc. On the northern slope, Patrick index and Shannon-Wiener index had a bimodal pattern with elevation and Simpson index and Pielou index showed a partially unimodal pattern. On the southern slope all the distribution pattern of species diversity indices showed two peaks, though that of the Patrick index was not obvious. These patterns were formed by the synthetic action of a variety of environmental factors in which elevation played an important role.