螺类牧食损害对沉水植物群落结构的调节

THE HERBIVORY EFFECTS OF SNAIL RADIX SWINHOEI ON SUBMERGED PLANT COMMUNITY

提要在受控实验条件下,采用实验生态学的方法,研究了螺类(椭圆萝卜螺)牧食损害对人工构建的沉水植物群落结构的影响。结果表明,螺类牧食损害降低了沉水植物的相对生长率及人工构建的群落生物量,且植物的生长率及群落的生物量与螺密度间有显著的负相关关系。牧食损害使沉水植物群落结构发生了显著变化,随着牧食强度的加大,群落中马来眼子菜与苦草的综合优势比迅速下降,而轮叶黑藻与伊乐藻则稳步上升。作者对调节沉水植物群落结构的影响因素进行了探讨,认为植物种类的生长特性使伊乐藻与轮叶黑藻在与苦草及马来眼子菜的竞争中占优势,椭圆萝卜螺的牧食损害则加速了这种优势地位的取得。

The herbivory effects by snail Radix swinhoei on submerged plant community were examined in an experimental station under artificial controlling in Taihu Lake, Jiangsu of China from May to July, 2006. The results showed that the grazing activity of the snail depressed the growth of 4 submerged plant species, and the total biomass of plant community were negatively correlated to snail density significantly. The plant community structure was clearly affected by the snail. With the snail density increasing, the summed dominance ratio decreased for Potamogeton malaianu and Vallisneria spiralis, whereas those of Elodea nuttallii and Hydrilla verticillata steadily increased. The main influential factors on the change of community structure were discussed in this paper. It was thought that the inherited attribute of plant decided the dominance of E. nuttallii and H. verticillata in local plant community; and the herbivory preference of the snail on P. malaianu and V. spiralis speeded up the occupancy of dominance by other 2 plants.