底泥对沉水植物生长和群落结构的影响

太湖流域中的5种土著沉水植物〔马来眼子菜（Potamogeton malaianus Miq.）、微齿眼子菜（Potamogeton maackianus）、苦草（Vallisneria spiralis L.）、黑藻（Hydrillaverticillata Royle）和金鱼藻（Ceratophyllum demersum L.）〕经人工配置成3种群落，分别栽植在3种不同类型的底泥上，经过53 d的试验，对人工配置的沉水植物的成活、生长和群落结构演变进行了研究.结果表明:有机质和营养盐含量较高、流动性大、稳定性差的淤泥底质不利于沉水植物的定植，植物成活率较低；氮、磷含量较高的淤泥底质比生泥底质更有利于沉水植物的生长，沉水植物具有较高的相对生长速率，但过于肥沃的底泥会对水生植物的生长产生抑制作用.试验条件下，营养盐含量低的底泥有利于提高生物多样性.3种人工配置的群落中，无论黑藻是否为主栽种，其优势度均明显增加，成为群落优势种.因此，人为配置的沉水植物群落是不稳定的，群落优势种和稳定的群落结构主要由环境条件决定. 

Influence of Sediment Condition on Growth and Community Structure of Submerged Plants

The survival rate, relative growth rate （RGR）, and structure succession of 3 communities composed of 5 native submerged macrophytes in Taihu basin, Potamogeton malaianus Miq., Potamogeton maackianus, Vallisneria spiralis L., Hydrilla verticillata Royle, Ceratophyllum demersum L., on 3 kind of sediments were investigated. After 53 days of transplantation, it was found that lower settlement ratio was obtained on sediment with the character of more fertile, more fluid and lower stability, while such kind of sediment was propitious to the vegetative growth of the plants. The plants in such fertile sediment showed higher RGR, but excessive nitrogen and phosphorous in sediments will act negatively. The sediment with lower nutrient content is beneficial to the increase of species diversity. It was evident that the dominance of H.verticillata increasedwhenever it was assigned as the dominate species or not. It is concluded that the structure of artificial community collocation of submerged macrophytes was unstable, and the dominant species and stable structure of community depends on the environmental conditions.