黑河下游额济纳绿洲植物群落特征与物种多样性研究

根据53个20 m×20 m样方调查资料,对黑河下游额济纳绿洲植物群落特征及物种多样性进行研究.结果表明:(1)调查样方的植物种类组成成分简单,科属组成较为分散.共有12科26属28种,以藜科、菊科为主,分别占21.43%和14.29%.种类优势现象明显,重要值>10的物种主要有胡杨、梭梭、柽柳、白刺、沙拐枣、苦豆子等;(2)不同植物群落类型的物种多样性指数均较低,且存在较大差异.以重要值计算的Margalef丰富度指数(Rm)介于0.027 3~0.567 7,Simpson多样性指数(Ds)介于0.677 8~0.999 3,Shannon-Weiner多样性指数(H′)介于0.098 2~0.367 3,Pielou均匀度指数(J′)在0.078~0.383之间,表明荒漠绿洲植物群落的结构简单、组织水平低;(3)样方统计的物种多样性指数纬向变化没有经向变化趋势明显,Ds和H′的纬向变化在42.02°N附近存在一个明显的高值区,经向变化呈先增后减的趋势,J′纬向变化与Ds和H′变化趋势较为一致,经向变化趋势不明显,呈连续波动的复杂变化特征.

Community Characteristics and Species Diversity of Ejina Oasis in the Lower Reaches of the Heihe River

Based on the investigation of 53 sampling plots(20 m×20 m),the examination of community characteristics and species diversity in Ejina Oasis were presented.The results indicated that:(1)the specific composition of community is simple and plant species is poor.There are 28 plant species belonging to 12 families,26 genera.Chenopodiaceae and Asteraceae are the dominating communities,which made up 21.43% and 14.29% of the total plants,respectively.The type predominance is obvious,and the importance value of some species is greater than 10,including Populus euphratica,Haloxylon ammodendron,Tamarix chinensis,Nitraria tangutorum,Calligonum mongolicum and Sophora alopecuroides.(2)The species diversity indexes of different community types are relatively low and have large difference among each other.Calculating from importance value,the Margalef dominance indexes(Rm) range between 0.027 3~0.567 7,Simpson biodiversity indexes(Ds) range between 0.677 8~0.999 3,Shannon-Wiener biodiversity indexes(H′) range between 0.098 2~0.367 3,and Pielou evenness indexes(J′) range between 0.078~0.383.(3)Along the latitudinal gradient,Ds and H′ have an obvious high value area in the vicinity of 42.02°N,and Rm and J′ are consistent with it;along the longitudinal gradient,Ds and H′ increased first and decreased later,Rm and J′ have no obvious trend and show a complex wave variation.In short,changes in species diversity along latitudinal trend are less obvious than that along longitudinal gradient.