黄河三角洲湿地水生植物组成及生态位

通过大范围的野外调查和室内测定,运用Levins及Pianka公式,对近代黄河三角洲湿地水生植物的构成及主要物种的生态位进行了研究.结果表明:调查样方内共有水生植物34 种,隶属于16科26属;各调查区域间物种组成和群落类型具有一定的差异性.区域形成的年份越久,其物种数和群落类型就越丰富;挺水植物中以芦苇的生态位宽度最大,为0.905,藨草的最低,为0.127; 沉水植物中轮藻、穗花狐尾藻、川蔓藻及小茨藻的生态位宽度较大,分别为0.783、0.673、0.669和0.640,金鱼藻的最低,仅为0.100.龙须眼子菜、大茨藻和苦草间,马来眼子菜和菹草间生态位重叠值较大,说明这几种植物具有相似的环境适应能力.物种的生态位宽度与该物种的分布范围及耐盐区间的大小存在显著的相关性,由此可以断定土壤和水体盐度是导致黄河三角洲湿地水生植物生态位分化的关键因子.

Composition of aquatic plants and their niche characteristics in wetlands of the Yellow River Delta

Based on field investigation and indoor measurement, the composition of aquatic plants and the niche characteristics of dominant species in wetlands of the Yellow River Delta were studied using Levins and Pianka formulas. A total of 34 species, belonging to 16 families and 26 genera were observed in the investigation plots. Species composition and dominant community types were significantly different among investigation regions. Higher species numbers and richer community types were observed in the regions with longer formation time. For emergent plants, Phragmites australis (0.905) and Scirpus triqueter (0.127) had the maximum and the minimum niche breadths respectively. For submerged macrophytes, Chara sp. (0.783), Myriophyllum spicatum (0.673), Ruppia maritime (0.669) and Najas minor (0.640) had relatively higher niche breadths and Ceratophyllum demersum had the minimum niche breadth (only 0.100). The niche overlap values among Potamogeton pectinatus, Najas marina and Vallisneria natans and the value between Potamogeton malaianus and Potamogeton cripus were relatively higher, indicating that they had similar capacity to acclimate to the environment. Species niche breadth was significantly correlated with its distribution range and salt-tolerance ability. Therefore, it can be concluded that salt contents in the soil and water are the key factors determining the niche differentiation among aquatic plants in the Yellow River Delta.