The Study Of The Relation Between Geological Environment And Plant Distribution Mode On The Wetland Of Yellow River Delta

The wetland of Yellow River Delta,which is with complex various types and unstable area changing,is the youngest and most characteristic wetland in the world. At present, its environment is relatively fragile under the influence of the climate changing, the nature disaster, the breaking-off Yellow River, the human activities, the raising sea-level, the seacoast erosion and the underground seawater infall, which leads the ecosystem has been destroyed. In this article, the main investigation and research areas include the northern old channel area of the Yellow River and the coastal wetland of the eastern nature protection area. The plant samples are the main vegetation of its station, such reed, tamarisk and seablite as the main investigation objects. The water samples are mainly the shallow groundwater. By studying and analyzing the water chemical composition, the isotopes of the soil and vegetation, the containing water quantity of the soil, the nutrition salt of the shallow groundwater and etc, the key point of the article is to find out the relation between the characteristics of the geological environment and the plant distribution on the wetland of Yellow River Delta. The main conclusions are as follows:The Cl^- content of the shallow groundwater has the reverse trend with the reed distribution. The Cl^- can obviously restrain the growth of the reed. While the affection of the Cl^- to the tamarisk flora depends on tow different conditions: when the content of Cl^- is more than 22 g/L, the Cl^- can restrain the growth of the tamarisk. While the Cl^- concentration is less than 22 g/L, the Cl^- concentration is in the direct ratio of the growth of the tamarisk. In the area of the seablite community, the groundwater is distributed by much more Cl^-, but the seablite can hardly grow in the area where the Cl^- content equals to or is more than 35 g/L.TheδD andδ¹⁸O values of the shallow groundwater of the whole investigation area locate among the values of the Yellow River water, sea water and rainwater. And the shallow groundwater on the north is mixed with the seawater in larger proportion than on the east. TheδD andδ¹⁸O datum of the different vegetations'leaves indicate that the water source of the reed is the shallow groundwater evaporated, the water source of the tamarisk comes from the deeper groundwater, which might mostly happen to exchange the isotopes strongly with the surrounding rock. The water source of seablite is more close to the sea water, which is under the stronger effect of evaporation. According to the containing water quantity of the columned soil sample, the eastern soil contains more water, the reason of which might be that under the affection of the present channel of the Yellow River, much more fresh water is transfused into the eastern soil leading to the containing water quantity of the whole area reaching higher level. From the point of view of the plant distribution, the status of the reed on the east is much better than on the north.The hygrophilous C₃ plant takes the advantage position in the investigation area. The carbon isotope of the soil in the north research area is C₄ plant carbon contributed most, while the carbon isotope of the soil in the east research area is C₃ plant carbon contributed most.From point of view of the nutrient content to analyze the vegetation distribution, various vegetations mostly distribute on the area where the values of NO₂^-, NO₃^- and NH₄⁺ are relatively low. The wetland zoology has the obvious effect of filtration on the nutrient N. The distribution of vegetation has not been affected by the changing values of PO₄^3- and SiO₃^2- and there are no obvious relevant rules of changing.