Study On The Evolvement And The Water-Environmental Effects Of The Freshwater Marshes Of The Changjiang River

Based on the comprehensive investigation, the type of marsh in the riparian and shoal of the upper reaches of the estuary of the Changjiang River which is both affected by runoff and tide wave is ascertained and it belongs to tidal freshwater marsh. What the marsh mentioned above is an important part of estuary and coastal wetland of the Changjiang River. According to the six typical marshes, rule of evolvement of the marshes is researched and especially, Beigushan marsh of Zhenjiang Neijiang who has typical significance in the aquicolous succession phase is studied. Based on three years' observation, characteristics of plants and community distribution are researched, cell model of marsh whose dominant plant is Phalaris arundinacea L in the growing phase and Phragmites communis Trin in the ripe phase is constructed, purification effect of two kinds of plant communities on non-point soure of water pollution in different seasons is obtained, purification mechanism of the marsh is analyzed, combining with the research of scene biogeochemical cycling of nitrogen and phosphorus in the marsh is studied, water-environmental effects of tidal freshwater marshes of the Changjiang River which is the prominent part of Aquatic-Terrestrial Ecotone is opened out. The research indicates:Under the continuous development of the alluvium, the wetland vegetation ecological process will undergo succession stage which include gramineous stage, mixed stage and arboreal-shrubby stage,Under the balance between the erosion and sediment, the reed community become the climax community in gramineous stage.Based on of three year's continuous research of the Beigushan wetland in Zhenjiang which is under the evolvement of hydroseres, the characteristics and the mutual effect of the soil, hydrology and plant have been studied. In the habitat with special hydrological and alluvial conditions in the upper reaches of estuary of the Changjiang River, the clonal plant Phalaris arundinacea L., Phragmites communis Trin., Zizania caduciflora Hand.- Mazz. and the Polygonum lapathifolium L. which embrace the capability of morphology variation can survive in the rigorous habitat, and become the dominant or concomitant plants.