Response Of Vegetation To Changes Of Hydrological Regime In Poyang Lake During High Water Period Based On Remote Sensing Data

Poyang Lake is the most important wetland in Jiangxi Province China,the largest freshwater lake of China,is the of three large lakes linked toYangtze River region?In the past 30 years,the hydrological regime in the Yangtze River and the Poyang Lake Basin has undergone significant changes under the combined effects of climate change and human activities.Based on the daily average water level data of Xingzi hydrological station,this paper uses the number of specific water level duration as the main index to characterize the fluctuation of water level,and study the change of hydrological situation from 1987 to 2015.According to the difference Lake elevation,the Poyang Lake is divided into 10 zones,Based on the 18 Landsat remote sensing images from 1988 to 2015,the NDVI index is used to study the change of vegetation in 10 zones during the 18 a.The use of unsupervised classification revealed area changes of hygrophilous vegetation,aquatic vegetation and the hygrophilous vegetation in 10 zones,in a 18 a period?The accuracy of unsupervised classification results was verified by field vegetation survey,the species numbers,aboveground biomass and distribution range of submerged macrophytes in Poyang Lake's East Lake during 2014~2016 were recorded and analyzed.In this paper,the method of redundancy analysis(RDA)is used to analyze the relationship between the water level change factors in recent years and last year and the area change of vegetation in different zones,during 1988~2015 years in Poyang Lake,to analyzes the relation between the change of water level in last year and that year,and the number of species,the area of distribution and the change of aboveground biomass of submerged vegetation in East Lake during 2014~2016.The following conclusions can be drawn in this paper:(1)In the 1988~2015 year,the water level in Poyang Lake decreased,and the duration increased during the dry season and the duration of the wet season decreased;(2)In the 1988~2015 year,the vegetation area increased with the year in Poyang Lake,and the main reason was that the area of emergent aquatic plants increased;(3)The increase trend of vegetation area in the zones elevation between 10.5 to 14.5 m is significantly higher than that in other areas;In the high elevation area of Poyang Lake,the annual difference of vegetation area is small;(4)The vegetation area in the wet season is negatively correlated with the last year's abundant water duration;The emergent aquatic vegetation area of the rainy season is positively related to the last year's low water season;the relationship among hygrophilous vegetation area and the water level was negatively correlated.(5)In 2014~2016,the species,distribution range and aboveground biomass of submerged vegetation in East Lake decreased obviously,and the average water transparency and water level had no significant influence on it.