三峡水库蓄水至156m水位后白夹溪消落带植物群落生态学研究

Plant Communities in Water-level-fluctuating-zone of Baijia Stream in Three Gorges Reservoir after Its Initiate Impounding to 156 m Height

三峡水库2006年10月底蓄水至156m水位后,已形成大面积消落带。为了解水位变动情况下,水库消落带植物群落的生态学特征,于2008年7～9月选择位于三峡水库腹心的澎溪河支流白夹溪,对145～156m高程消落带进行了调查。从植物群落的物种组成、生活型和结构特征等方面进行分析,并运用TWINSPAN法对消落带植物群落进行数量分类。结果表明,澎溪河支流白夹溪消落带植物群落物种较丰富,共有高等植物96种,分属36科73属,植物区系地理成分简单;植物群落生活型以一年生植物为主;植物种类构成以湿生、水生植物为主,占总种数的76.04%。TWINSPAN数量分类将调查的68个样方分为10个植物群落类型,其中最具代表性的群落有苍耳(Xanthum mongolicum)+狗牙根(Cynodon dactylon)群落、苍耳群落、双穗雀稗(Paspalum paspaeoides)群落、双穗雀稗(Paspalum distichum)+空心莲子草(Alternanthera philoxeroides)群落和白茅(Imperata cylindrica)群落,群落特征明显表现出对水位涨落及小生境差异的适应。

After the winter flooding in October,2006,the water table became 145 m again,receding from 156 m,and a large area of marshes were formed in the lowland of the drawdown zone of the Three Gorges Reservoir （TGR）. In order to realize the plant community of the water-level-fluctuating-zone in the height from 145 m to 156 m,The plant community was investigated in the water - level - fluctuating - zone of Baijiaxi Stream from June to September,2008. Based on field survey,the species compose,life-form and population structure char- acteristics were studied,and the plant communities were numerically classified by using the method of two - way indicator species analysis ,TWINSPAN. A total of 96 species of vascular plants were recorded in the water-level- fluctuating-zone,belonging to 36 families and 73 genera. 33 families of spermatophytes belong to 4 geographic elements,and the floristic composition is simple. The life - form of the plant community was characterized by therophytes. An analysis to water ecological types indicated that water plants were the dominant type with a total sum of 66 species. By TWINSPAN,68 quadrates collected from the study area were classified into 10 types,the dominant ones were Form. Xanthum mongolicum ＋ Cynodon dactylon,Form. Xanthium sibiricum,Form. Pas- palum paspaeoides,Form. Paspalum distichum ＋ Alternanthera philoxeroides and Form. Imperata cylindrical. Plants showed some characteristics to adapt water table dynamics and habitat changing.