Studies On Biology And Ecology Of Potamogeton Pectinatus L And Its Application For Ecological Restoration In Dianchi Lake

Potamogeton pectinatus L is perennial submerged aquatic macrophyte with a parvopotamid growth form. It is cosmopolitic in its distribution and inhabits many different environments from the south to the north in China.Potamogeton pectinatus is a tolerant species with wide ecological amplitude and can survive in heavy polluted waters and under shady environmental conditions. Presently, Dianchi Lake has been serious polluted. Cyanobacteria blooms were serious, which led to a low transparency. While the other submerged aquatic macrophytes have disappeared, this species still suffer from Dianchi Lake and come into being scale of community.At present, rehabilitating damaged ecosystem is one of chiefly direction of ecological research. Aquatic plants play an important role in restoration ecology. Because of its evident, Potamogeton pectinatus must be worth further research as a species of pioneer in rehabilitating aquatic vegetation.Firstly, the correlative theories and practices of restoration in lakes and studies on this species were reviewed in this paper. Secondly, by means of observation in situ and control experiment, general characteristics, life cycles and biomass production in Potamogeton pectinatus was studied. The results showed that Potamogeton pectinatus occurs in many different habitat types, for instance both on alkaline fresh and brackish waters, in standing and running waters and in waters and sediments of different trophic status. Further it is striking that this species can also survive in waters where depth is 3m with only 30cm Secchi disc and hyper-eutrophication waters.In aspect of communication composition, Potamogeton pectinatus usually go with P.malaianus and Myriophyllum spicatum.Potamogeton pectinatus is a species with high canopy form, and usually produce many side-branches. Sometimes, especially at the end of the growing season, the branches are concentrated in the upper part of shoots. Thus forming dense leaves at the water surface. As a result, Potamogeton pectinatus possesses predominance in competing light with algae.Potamogeton pectinatus is a morphological plastic species with different habitat environment. This species was adapted to thrive and survive under many different environmental conditions. This makes that Potamogeton pectinatus has comprehensive and effective survival strategies.The results of seed germination experiment in situ indicated that seed germination rates of Potamogeton pectinatus were rather low, only 6% or so. The populations of this species mainly produced from the tubers. The main function of the seeds (achenes) appears to be dispersal and long-term survival of the species.The results of seed germination under different treatment showed that constant higher temperature was not dominant factor for inducing germination. Seed germination rate was greatly increased by the treatment of alternating temperature, peeling off the seed capsule, acid with 0.5 mg-1 H2SO4 and stratification. The treatment with KNO3, GA and thiourea(H2NCSNH2) cannot increase seed germination rate.The results of the influence of different light intensity and temperature on photosynthesis showed that net photosynthetic rate in Potamogeton pectinatus was higher between 10 and 25℃, and maximum was at 25 ℃. The net photosynthetic rate decreased greatly at 30 ℃. The light compensation point of Potamogeton pectinatus was increased from 385 to 1256Lx while temperature was raised from 10 to 30 ℃.In addition, according to light extinction, light compensation point and fluctuation of water level, distribution of in Dianchi Lake was limited within 3m depth, which was validated by field investigation.The result of experiment also showed that effects of Cyanobacteria blooms on of growth of Potamogeton pectinatus was not marked, but biomass of Potamogeton malaianus decreased 57.1 percent in twenty-two days under the pressure of a great of Cyanobacteria.Some experiments in this paper have indicated that this species has a great ability of purifying waters and decrea...