伊犁河谷北坡垂直分布格局及其与环境的关系——一种特殊的双峰分布格局

The vertical distribution of vegetation patterns and its relationship with environment factors at the northern slope of Ili River Valley: a bimodal distribution pattern

针对伊犁河谷北坡山地的植物多样性和土壤因子沿海拔的分布方式进行研究。对研究地海拔1000—2200m植物和环境特征进行调查,选取群落样地总数为44个,共调查到植物种155种,其中乔木7种、灌木18种、草本130种,调查到的群落类型完全涵盖了研究区所有沿海拔上升的群落类型。通过NLFS高级模拟显示总的物种丰富度、Simpson指数、Shannon-Wiener多样性指数、Pielou均匀度指数都与海拔呈现先升高后降低,再升高的一个特殊分布格局。出现了两个较高的物种丰富度地带,其中一个是低山荒漠到落叶阔叶林,另一个是山地草原到针叶林带。土壤养分和盐分也表现出了类似多样性的分布格局。通过PCA和相关分析表明,环境因子控制着物种丰富度和它的分布方式。水分在低海拔比较重要,在高海拔温度比较重要,而由于逆温层的作用,在较高海拔的针叶林带物种多样性出现了上升。物种丰富度与土壤总盐呈现显著负相关关系(r=-0.343),与土壤全盐也呈现显著负相关关系(r=-0.341)。Simpson指数与土壤pH值呈现显著负相关关系(r=-0.465)。Shannon-Wiener指数与土壤电导率呈现显著负相关关系(r=-0.367)。Pielou均匀度指数与土壤电导率呈现极显著负相关关系(r=-0.477),总之,多样性指数和土样盐分表现出了强相关性。这个研究为伊犁河谷植被与植物资源的保护和利用提供重要的科学依据,为河谷区山地植被与环境关系提供基础科学理论,为山地退化植被的修复提供参考案例和可借鉴的基础性数据。

The Study of the relationship between vegetation and environment have become important areas of vegetation ecology,different environmental factors of earth′s surface leading to the different distribution of plants and vegetation.Ili River Valley is a ＂U＂ shaped valley,which was known as one of Xinjiang′s most beautiful places.In this closed or semi-closed valley,there is kind of special ＂cold lake effect＂： In winter,as cold air accumulating in the bottom,the air in the valley forms a special ＂inversion layer＂ zone at altitude of 800—2000 m.In this special mountainous valley environment,the study of the vertical distribution patterns is of special significance.This study is set out to investigate the vertical distribution of the soil chemical properties,and to find out the the relationship between vegetation and the soils,which should provide important information for future vegetation restoration and reconstruction.Patterns of plant diversity and soil factors along the altitudinal gradient on northern slope of Ili River Valley were examined.Plant and environment characteristics were surveyed from the altitude of 1000 to 2200 m.There were a total of 155 vascular plants,133 herbages,18 shrubs,and 7 tree species in 44 sampled plots.The plant richness of vegetation types generally showed a special pattern along altitude,with a bimodal change of plant species number at 100m intervals of altitude.The two belts of higher plant richness were in transient zones between vegetation types,the first was in the transient zones from lower-mountain desert to forest,and the second in the transient zone from dry grass to coniferous forest.Soil nutrients and salt also showed a similar distribution pattern.Matching the change of richness of plant species to environmental factors along altitude and correlating these by PCA and relation analysis revealed that the environmental factors controlling species richness and its pattern were the combined effects of soil salt and nutrients.Water was more important at low altitude,and temperature was more important at high altitude.The effect of the inversion layer seems made the coniferous forest at high altitude had high plant species diversity.Species richness and soil total dissolved salt had a significant negative correlation（r =-0.343）,and soil total salt also had a significant negative correlation with species richness（r =-0.341）.Simpson index and soil pH showed a significant negative correlation（r =-0.465）.Shannon-Wiener index and soil electrical conductivity showed a significant negative correlation（r =-0.367）.Pielou evenness index and soil electrical conductivity showed a very significant negative correlation（r =-0.477）.In a word,there was a strong negative correlation between plant diversity index and the index of soil salinity/alkalinity,which confirms the negative effect of soil salinity/alkalinity on plant or vegetation.This study of altitudinal pattern in Ili River valley provides an important scientific basis for protection and utilization of plant/vegetation resources in this region,should enrich the theory of vegetation-environment relationships,and is also helpful in the future practice of the restoration,reconstruction of the degraded vegetation cover.