中文摘要：

地面节肢动物是荒漠生态系统的重要组分之一,在维持荒漠生态系统的结构与功能方面起着关键作用。但至今尚缺乏对黑河中游沙质荒漠地面节肢动物群落组成及多样性季节变异规律的研究。文中以黑河中游沙质荒漠生态系统为研究对象,在5月上旬、7月和9月中旬三个典型时期采用陷阱法对地面节肢动物群落进行了系统调查,并利用多元方差分析和群落排序等方法定量研究了沙质荒漠地面节肢动物群落的季节变异规律。主要结果如下：（1）黑河中游沙质荒漠生态系统主要的地面节肢动物群落存在明显的季节变异,7月和9月地面节肢动物群落较为相似。（2）从5月到9月,地面节肢动物群落活动密度逐渐降低,而均匀度指数逐渐增加;地面节肢动物类群丰富度和多样性指数变化规律接近,7月和9月显著高于5月,优势度指数变化规律刚好相反。（3）不同地面节肢动物类群的季节变异规律不同。如从5月到9月拟步甲科活动密度逐渐降低,蚁科活动密度在7月显著高于9月,而9月蚁科的活动密度又显著高于5月。

英文摘要：

Ground arthropoda are of the important components of desert ecosystems and play a key role in maintaining ecosystem structure and function. Up to now,relatively fewer studies have explored seasonal variation of arthropod community composition and diversity of sandy desert ecosystems in the Heihe River basin,NW China. We investigated the composition and diversity of ground arthropod communities using pitfall trapping method in the early-May,mid-July and mid-September in the sandy desert of the middle Heihe River basin. Main findings of our study are as follows.（ 1） Seasonal variations of ground arthropod community composition and diversity in a sandy desert ecosystem were found,and a similar ground arthropod community composition and diversity was observed between July and September sampling periods.（ 2） The activity density of ground arthropod community decreased from the early-May census to mid-September census,and an inverse pattern was observed on evenness index of ground arthropod community. Group richness and diversity index in the mid-July and mid-September census was significant higher than that in the early-May census,and an inverse pattern was observed on dominance index of ground arthropod community.（ 3） There was a significant within-season variation in the activity of the ground arthropods. For example,the activity density of Tenebrionidae decreased from the early-May census to the mid-September census. In addition,the activity density of Formicidae was significant higher in the mid-July census than that in the May and September censuses,and a similar pattern was observed between the early-May census to September census.