Ecological Functions of Aquatic Vegetation in East Taihu Lake and Its Reasonable Regulation

Abstract

水生植物在浅水湖泊中具有净化水质、保护生态环境、生产植物产品等生态功能, 同时也有加速湖泊淤浅、引起水质污染等环境负效应, 通过对植被结构的调整和利用方式的改进可以优化其生态功能东太湖水生植物覆盖率97%, 年生产量1120325t, 吸收同化氮3916t, 磷486t;年收获利用水生植物599295t, 带走氮1891t, 磷296t, 相当于东太湖年外源氮、磷输入量的28%和57%;但每年仍有521030t的水生植物残留在湖中, 引起局部湖区的水质污染和淤积, 尤以茭草区最为严重。伊乐藻在东太湖的大面积推广每年可增加水生植物收获利用量约50000t, 以沉众植物取代茭草的试验也取得了成功。东太湖水生植被改造工作还有待进一步完善;In shallow lakes.aquatic plants play very improtant roles in primary production and environ-mental protection.On the other hand.it can also cause silting-up by adding large amount of plant material to the lake bottom and release pollutant to the lake water when it dies and decays.The functions of aquatic plants car/be regulated reasonably by manipulating the structure and species composition of aquatic vegetation of the lake.In East Tathu Lake, more than 97% of the lake surface was covered by aquatic plants, which abso rbed 3916t nitrogen and 496t phophorous from the lake in a year to produce 1120325t plant biomass(fresh weight) About 599295t plant bio-amsswas harvested from thelaketo remove 198lt nitrogen and 296t phosphorous, equalto 28% of the external nitrogen load to remove 57% of the extecna1 phophorolls load of the Inke.There was stil1 521030t plant biomass remained and decayed in the lake which caused serious water Pollution and siliting-up of the lake basin Elodea Nuttallii was introd uced to the lake in 1986 and transplanted on a large scale in the past ten years.About 50000t of Elodea Nuttallii were har-vested as fish fod der in 1993 An experiment was carried out successfully to replace Zia lati in the 1ake with submerged plants.There alre still a lot to do to complete the task of reason-able regulation.