Study On Management Zoning Of Poyang Lake Wetland Based On Spatial-Temporal Changes Of Ecosystem Services In The Wet-Dry Cycling

Since the 21 st century,affected by climate change and human activities,the relationship between rivers and lakes in the middle and lower reaches of the Yangtze River has changed significantly.Poyang Lake is one of the most important lakes in the middle and lower reaches of the Yangtze River.Its wetland system plays an important ecological role in the Yangtze River Basin.Poyang Lake wetland is a multi-type wetland composed of natural-economic-social complex,which is spatially discontinuous patch-like distribution,resulting in the complexity of the Poyang Lake wetland ecosystem.The hydrological changes of Poyang Lake are significant year by year.Floods and extreme drought events are frequent and increasingly serious,causing the degradation of lake wetland ecosystem.This study is based on RS and GIS,and uses Landsat8-OLI as the basic data to analyze the land use change of Poyang Lake wetland during the wet season to dry season.And calculated the spatial and temporal changes of biodiversity,temperature regulation and water conservation in Poyang lake wetland during wet season to dry season by using CASA model,radiation transfer equation method and water balance method.Finally,the three kinds of ecosystem service standardization results are analyzed as cold hot spots,and the results are divided into Poyang Lake wetland management zones and corresponding management suggestions are proposed.The research results of this paper are as follows:a.Variations in Poyang lake wetland water levels lead to decline in land use types during wet to dry seasons.The wetland became a lake during the wet season,and the land use type was mainly waters,which was close to 95% of the total area of the study area.At the same time,the tidal flats and most grasslands had been flooded by the lake.During the dry season,the water level of Poyang Lake dropped significantly,and the area of the water area was reduced to about 30% of the total area of the study area.Most of the reduced water areas were transferred into beaches and grassland,accounting for 35% and 29% of the total area of the study area,respectively.The area of cultivated land,sandy land and construction land changed slightly during the two periods;otherwise,the area of forest land was the most stable.b.The results of various ecosystem services in the study area vary greatly during wet season to dry season.In terms of biodiversity,the type of land in high water period is relatively single,the coverage rate of water area is more than 90%,the NPP range is large,and the result of polarization is obvious.During the dry season,the area of water area is reduced,the landform is rich and the vegetation is withering,and the NPP results are flat and concentrated.In terms of temperature regulation,the temperature regulation during the wet season is gradually decreasing from the east and the west to the middle,and the local performance is that the construction land and sandy land play a significant role in increasing temperature.The regulation of temperature in dry season has no obvious regularity in spatial distribution,but the warming effect of construction land,sandy land and beach is still obvious.In terms of water conservation,the contribution rate of water in the wet season is the most prominent,and the land type with the largest contribution rate in the dry season is grassland.Although the total proportion of forest land is not the highest,from the perspective of the average value of water conservation,it is the highest in terms of water conservation.c.The analysis of cold and hot spots in the overall index of ecosystem services during the wet season is mainly based on non-significant areas.The distribution of hot spots shows the characteristics of "more north but less south",and the distribution of cold spots is sporadic.The overall distribution of hotspots during the dry season showed a pattern of "east more but less west",while the distribution of cold spots was decreasing from northwest to southeast.Based on the analysis of Poyang lake wetland ecosystem service index in dry and wet season,the thesis divides Poyang lake wetland into five regions and puts forward management Suggestions for different regions in different periods.