| Hangzhou Bay wetland is rich in resources with various kinds of rivers, lakes, reservoirs and water surfaces for Breeding, beaches widely distributed. The economy development is rapid however there still exists several problems such as the shortage of land resources and ostensible contradiction between people and land. This article will make use of the remote sensing data through the Hangzhou Bay area since the 1970 to analyze the landscape pattern of dynamic evolution and its driving forces, to evaluate the value change of landscape of wetland ecosystem service and to provide a theoretical basis for wetland conservation.The contents of the thesis include:(1) The article made use of the Landsat MSS and Landsat TM image in research area in 1976,1990 and 2005, on the basis of remote sensing image pre-process to establish the classifying system of wetland landscape. Also, it utilized the GIS spatial analytic method to transformation process of various kinds of wetland and through calculation of landscape pattern index, to analyze characteristics of landscape level and landscape type.(2) Based on the ecology and economics theory, also remote sensing data in 1976, 1990 and 2005, the article analyzed the service value change of different landscape ecosystem.(3)Combining natural factors such as climate, hydrogeology with other social factors including population, economic development and policies, the paper analyzed the driving force of the past 15 years in the study area in quantity and in quality.The main conclusions of the paper list as follows:(1) The landscape level and the landscape type index showed that during the past 30 years, there was a tremendous change in the land use type in the area, which to some extent indicated the way of economy dishevelment and land use. During 1976-1990, the diversity of the overall landscape pattern index, the degree of landscape fragmentation has been enhanced and the Landscape structure is more complex; between 1990 and 2005, there is no big change in pattern diversity, homogenization and fragmentation while urban and rural settlement rate significantly increased, indicating that the overall ecological and environmental protection situation is not optimistic.Landscape type transfer analysis showed that this stage of 1976-1990 natural wetland in the study area decreased with main flowing to urban and rural settlements and paddy field landscape, and almost all types of wetlands show signs of this change. During 1990-2005 the area of urban and rural settlement substantially increased, due to the increasing number of paddy field and dry land.(2) Nearly 30 years, the area forests, rivers,(including wetlands) ponds increase 26.31%,35.55%,224.93%, respectively. However, the area of farmland, lakes, and coastal wetlands respectively reduce 14.09%,60.87%,26.55%. The expansion of urban and rural mining area as well as the reduction of lakes, coastal wetlands and so on led to a decline in the decline of the service value of the whole eco-system.But the increase of forest area, lake area and pond area to a certain extent made up the lost. Ecosystem service value of the study area reduced from $ 60.3 billion in1976 to 5.575 billion yuan in 2005 with reduction rate of 7.55%, a net decrease of 455 million yuan. The decrease of the value of ecosystem services during the first 15 years was 0.21%, then it was 0.3% during the latter 15 years, indicating the ecological damage to the environment of the study area became more serious.It is the primary means to enhance the value of ecosystem service of Hangzhou Bay wetland by increasing the rate of forest coverage, by protecting rivers, as well as by preventing the sprawl of urban and rural mining area. This article attempts to evaluate the Hangzhou Bay wetland ecosystem service value and it still need to be further improved as the cognition of wetland raises and the assessment method improves. Just as Costanza said estimates on the value of the global ecological environment is only a preliminary attempt, with many deficiencies such as the assumption of natural capital and economic value. (3) In regard of natural factors, the temperature of the study area from 1990 to 2005 in major cities is gradually increased. And during this period the sever fluctuation of the average temperature, with other factor remained unchanged, is bound to accelerate the evaporation process, later caused the reduction of water natural wetlands area. During 1990 to 2005, there is a big fluctuation in major cities precipitation. average annual precipitation decreased by almost 200mm as a whole and the reduction of precipitation led to the utilization and development of marshes, tidal flats and other wetlands. the results showed the same trend between the decrease of natural wetland area and average redaction of rainfall.In regard of social economic factor, Non-farm population was rapidly increasing while the natural wetlands was reducing, which led to the conclusion that urbanization was an important reason for the reduction of wetland. The rapid economic development has led to a significant expansion of construction land and according to wetland transfer matrix, a large number of natural wetlands and semi-natural wetlands flew to construction land, demonstrating the expansion of construction land in the process of economic development was at the price of disappearance of natural wetland. Laws and regulations about land management, farmland protection, wetland protection played an active role.The quantitative analysis results showed that the coefficient of the economic development factor was -1.581. In other word, the economic development exerted an significant impact on the reduction of natural wetlands. The coefficient of population factor was positive with a value of 0.387, indicating that there was a positive correlation with agricultural population and natural wetland. That is to say, the increasing number of non-farm population showed a negative relationship with the reduction of natural wetland. To sum up, the impact of demographic change on wetland loss is enormous. |
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