| Based on the enviroment of the Nandagang Wetland, combining the outside investigation and inside analysis,adopting the mathematical analysis methods such as the principal component analysis(PCA),regression analysis,correlation analysis etc. the type of wetland ecosystem,the flora of the wetland plant, the type, the function, the formation and succession and the outside influencial factors of the vegetation, the ecological conditions and biomass of the reed population are all studied. The main results can be concluded as follows:1) The Nandagang Wetland is a freshwater one close to the Bohai Sea. Its ecosystem can be divided into two parts: natural ecosystem and semi-artificial ecosystem. The former includes aquatic ecosystem and terrestrial ecosystem; The latter is composed of artificial pond and forest belt ecosystem on the dikes.2) In the Nandagang Wetland,the plant are 141 species, belonging to 48 families and 110 genera. Among thein,2 species and 1 species are respectively pteridophyta and gymmospermae. All the others are angiosperm. The number of genera and species amount to 97.27% and 97.87% of all the genera and species of the wetland. Acceding to the number of species, thethree of the biggest families are Asteraceae, Poaceae and Legumimosae. They play a big part in the flora and vegetation of the wetland. And they are constructive speicese or dominant species of most of the communities.The flora in the Nandagang Wetland consists of 13 geographical elements. Among them, the cosmopolitans are 30 genera, 28.04% of the entire angiosperm flora of the wetland, and it is consistent with the intrazonality of the wetland ecosystem; The temperate elements ,44 genera, 41.12% of the angiosperm flora, is the dominant one. The result is deteimined by its limate.3) The vegetation of the wetland can be divided into two types: cultivated vegetation and natural vegetation. The cultivated vegetation is composed of man-made forest, artificial scrub and field crop; The natural vegetation consists of 4 vegetation types, 10 formations and 10 associations. Among them, the reed association is dominant.4) The vegetation of the wetland can provide several functions as below.conserving biodiversity, providing economic production, touring and convalescing, ecological function such as regulating climate, purifing water, resisting storm surge and so on.5) According to the results of investigating and analyzing plenty of sample plots and combing the conclusions of the succession process in the Yellow River Delta, the formation and succession of the wetland vegetation has two ways. One is the succession process from the bare salina, the other is the one from submerged and denuded land.6) There are two outside factors, which influence the wetland vegetation. They are natural factor and anthropic factor. The former one consists ofclimatic factor, hydrological factor, pelagic factor etc. The latter one includes petroleum industry, angriculture, salt industry and aquaculture and so on.7) After analyzing the relationship among biomass above ground, height and basal diameter of reed, the regression equation model can be concluded as:W=7.03845(D2H)0.905385.At the same time, some other models can be got also, such as the seasonal dynamics model of biomass above ground and biomass under ground, the partitioning model of biomass above ground.8) Through the principal component analysis of all environmental factors, the contributive rate of the first two pricipal components in 83.70%. Among them, water content and saline content in the soil play the leading role. So they are the dominant factors which influence the reed community.
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