贺兰山灌丛群落物种多样性海拔格局及环境解释

Altitudinal Pattern and Environmental Interpretation of Species Diversity of Scrub Communty in the Helan Mountains,China

贺兰山是一条重要的草原与荒漠的自然地理分界线,也是我国西北地区一道重要的生态屏障。灌木是贺兰山最主要的植被组成,但对贺兰山灌木多样性的分布格局及其影响因素却很少有专门研究。本文对内蒙古贺兰山西坡沿不同海拔分布的13类主要灌丛群落进行了野外调查,探讨物种多样性沿海拔梯度的分布格局及其与海拔、土壤、人为干扰等环境因子的关系。结果表明:(1)灌木层与草本层的物种丰富度随海拔上升总体呈微弱的单峰格局,Shannon-Wiener指数(H')、Simpson指数(D)和Pielou均匀度指数(E)随着海拔上升均未表现出明显的垂直分布格局。(2)除Pielou均匀度指数外,灌木层郁闭度与下层草本植物的物种多样性呈显著的二项式回归关系,最大值出现在约40%的灌木层相对盖度处。(3)海拔、坡度和土壤质地等多种环境因子共同影响着贺兰山灌丛群落的物种组成及其多样性垂直分布格局,其中海拔是主要的限制因素。本研究有望实现对该地区灌丛群落研究的扩展和完善,并为灌丛资源的科学保育及管理提供参考。

The Helan Mountain is an important natural geographical dividing line between grassland and desert,and also an important ecological defense in northwest China.Shrubs are the most important vegetation composition in the Helan Mountain,but there is little research on the distribution pattern and influencing factors of shrub diversity in Helan Mountain.In this paper,13 types of shrub communities distributed at different altitudes along the west slopes of the Helan Mountain of Inner Mongolia were investigated in the field,and the vertical distribution pattern of species diversity and its relationship with environmental factors such as altitude,soil and human disturbance were discussed.The results showed that:(1)The species abundance of shrub layer and herb layer showed a weak unimodal pattern with the elevation gradient as a whole,but the Shannon-Wiener index(H′),Simpson index(D)and Pielou evenness index(E)did not show an obvious vertical variation.(2)Except for Pielou evenness index,the canopy density of shrub layer had a significant binomial regression relationship with the species diversity of herbaceous plants in the lower layer,with the maximum occurring at about 40%of the relative coverage of shrub layer.(3)Various environmental factors such as altitude,slope and soil physical and chemical properties jointly affected the species composition and the vertical distribution pattern of diversity of shrub communities in the Helan Mountain,and altitude was the main influencing factor.This study is expected to expand and improve the study of shrub communities in this area and provides reference for scientific conservation and management of shrub resources.