Analysis And Evaluation Of Spatial Structure, Wetland Functions And Stability Of Poyang Lake Ecosystem

In this paper, the spatial structure of Poyang Lake ecosystem and the wetland functions were analyzed by making use of 3S technology and statistical datas, and the indexs system to the stability evaluation of Poyang Lake ecosystem was established on the basis of the analysis.The main contents and conclusions are as follows:1. The technique and route were determined through considering the advantages of 3S technology in spatial analysis of large areas, and the study area was divided into two regions based on the specific research contents, which included lake district and lake basin. Then the databases of landscape structure were established with landscape indexs selected.2. Lake district: The changes of landscape structure of 1990, 2000, 2005 and 2010 were analyzed, and the storage capacity of flood in Poyang Lake was calculated during these four years, at the same time, the databases of the storage capacity of flood were established and the changes were analyzed. Then, landscape structure and the storage function of Poyang Lake were analyzed based on the grey correlation method, and correlation degree of diversity index with storage capacity was the highest in the overall landscape, which was 0.75, correlation degree of area of forest land with storage capacity was the highest in single landscape, which was 0.85.3. Lake basin: First, the interaction between landscape structure of wetland and hydrology was made a brief introduction, the unique role of the wetland and the unique process of eco-hydrological process which the two formed were pointed out. Then, the mathematical relationship of landscape structure of wetland and water level was established, which showed the trend of spatial structure of Poyang Lake wetland along with the water level, and the wetland unique structure was showed in water level. Finally, the wetland functions were analyzed, which included climate regulation, water purification and maintenance of migratory birds habitat, at the same time, water level was regarded as the representative to explore its relationship with the various functions. In climate regulation, the function was analyzed by comparing Duchang and Jingdezhen, and found that if the water level rose in 1m, the difference in temperature between the day and the night woud reduce about 0.378℃ in Duchang. In water purification, found that wet season was better than dry season, and if Xingzi water level rose in 1m, the comprehensive pollution index would decreased about 0.098 in Poyang Lake. In maintenance of migratory birds habitat, HSI(habitat suitability index) model was established for regional statistics, and found that water level and distribution of landscape structure were the best for migratory birds when Xingzi water level was 11.70 m.4. Based on the above analysis, the indexs system to the stability evaluation of Poyang Lake ecosystem was established, which was analyzed in big and small two scales. At the same time, the system was divided into 3 levels, which included the target layer, the criterion layer and the index layer. Then, through the analytic hierarchy process to construct the judgment matrix so that the index weight was obtained. Finally, combined with the stable value of single index, the stable value of wetland function index was 0.581, which was in general stable condition, the stable value of natural factor index was 0.730, which was in acomparatively stable condition, the stable value of human factors index was 0.719, which was in acomparatively stable condition. O n the whole, the stable value of Poyang Lake ecosystem was 0.693, which was in acomparatively stable condition.