| Based on the Zoige area, this paper selects Normalized Difference Vegetation Index(NDVI) and Enhanced Vegetation Index(EVI) of the MODIS data,and combining with DEM and SLOPE data to build decision tree for the extraction of the wetland information; Choosing the methods of maximum/minimum classification reprocessing to extract information of wetland post-processing, which has a good effect by means of research of precise evaluation. Analyzing the kinds of wetland landscape pattern and studying the evolution of landscape structure and the features of spatial distribution; From two aspects of natural factors and human factors to analyze the driving force of the wetland changes in Zoige area; Which will provide the basises for management and protection of wetland in Zoige area.The main results of the research are followed:(1)According to the classification of the wetland standard and characteristics of the data, the wetland is classified as lake / river wetland, grassland / meadow wetland, swamp meadow wetland and swamp wetland in Zoige area.(2)Obtaining the distribution map of wetland for fifteen years in Zoige area, there is mosaic, projection, cutting and other processing of MODIS/NDVI and MODIS/EVI, and have small noise and significantly spectral characteristics after processing by Harmonic Analysis of Time Series(HANTS), combining the digital elevation model(DEM) and gradient data to build the decision tree. lastly, having the classification of post-processing and the accuracy test to obtain the distribution map of wetland Zoige area.(3)There is an analysis to the results of landscape pattern of wetlands in fifteen periods.The changes of patch area in land scape of wetland in research area, as well as fragmentation index, dominance index, diversity index and evenness index are evaluated. The results of analysis show that the total area of wetlands is decreasing entirely, the fragmentation degree is increasing, the degradation rate of grassland / meadow is faster than the other wetland in Zoige area. At the same time, the gap of the dominance in various landscapes is increasing while its diversity and evenness degree are decreasing.(4) Analysis of the driving factors of wetland landscape pattern changes in Zoige area. Combined the result of analysis with the situation of wetlands and economic conditions and other statistics of data in Zoige area, this paper summarize the driving factors of the changing landscape pattern of wetland in Zoige area. Five factors are below: geographical Specially area determines the sensitivity of the ecological environment, under the condition of global warming, climate change is more obvious in Zoige area, the temperature is rising and rainfall is also increasing. Therefore, the local climate get warm and wet. Climate change is a major factor of reduction of wetland area; Explosion and overgrazing of population and irrational human activities are all the the key factors which lead to reduction of wetland in Zoige area; Rodents and insects also accelerate degradation of wetland; Although the development of tourism has brought economic benefits, at the same time, it has brought some pollution for wetland environment and water resources; Establishments of natural reserve of wetland and a series of measures of protection are beneficial to the degradation of wetland in Zoige area. |
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