Landscape Pattern Dynamics And Stability Analysis Of Dongting Lake Wetland Based On Characteristic Scale

There are various types of wetlands in Dongting Lake Basin,including Alpine swamps,rivers,reservoirs,ponds and lakes,which have great ecological service value.For a long time,due to the interference of human activities,climate change and other factors,the ecological environment of Dongting Lake has been deteriorating,the wetland area has been shrinking,the water pollution has been aggravating,the wetland drought has become more and more obvious,and the biodiversity has declined.It is of great significance to study the temporal and spatial changes and stability of Dongting Lake wetland landscape for wetland protection and restoration.Taking Dongting Lake as the research object,this paper uses multi-source image data,combined with the characteristics of vegetation and water level information to extract the wetland vegetation data of Dongting Lake.Based on the theories and methods of landscape ecology and geostatistics,this paper analyzes the landscape pattern,spatial variation characteristics of landscape stability,spatial correlation characteristics of landscape stability and factor driving characteristics of Dongting Lake wetland.The results are as follows:(1)The dominant landscape of Dongting Lake wetland is reed land,water area and mudflat;From 2015 to 2020,the area of reed land increased by 180 km~2,the area of Lake grassland decreased by 89 km~2,the area of woodland decreased by 190 km~2,and the area of water area and mudflat fluctuated between 700-800 km~2;From the perspective of spatial distribution,the water area and mudflat have good connectivity,which constitute the natural corridor of Dongting Lake wetland landscape;Reed land and lake grassland are scattered in the landscape;The forest land is mainly distributed in the West Dongting Lake and the South Dongting Lake;The germinated forest is mainly distributed in the South Dongting Lake.(2)The landscape level of Dongting Lake wetland is characterized by a grain size range of 90m-100m.The characteristic grain size of Lake grassland is 70m,the characteristic grain size of water area and mudflat is 90m,the characteristic grain size of forest land is 90m,the characteristic grain size of reed land is 90m,there is no obvious characteristic grain size in germinating forest.In the 90-100m grain size domain,the landscape fragmentation,edge contrast,landscape patch agglomeration and landscape spatial pattern complexity of Dongting Lake wetland decreased significantly,indicating that the"special action"played a positive role in improving the landscape ecological environment of Dongting Lake.(3)The spatial range of 1500m and the spatial granularity of 90m are the characteristic scales of the landscape stability of Dongting Lake wetland.n this scale,the wetland landscape stability presents a"U"type change,which continues to decline from 2015 to 2018,and increases from 2018 to 2020;In terms of space,the spatial distribution of landscape stability of Dongting Lake wetland is different,the overall landscape stability in the East is higher than that in the west,and that in the north is higher than that in the South;the high value of landscape stability of international important wetland in East Dongting Lake is the most widely distributed area,and most of them are concentrated in the middle and south,and The landscape stability of the southwest part of the international important wetland of South Dongting Lake is relatively high;The landscape stability of West Dongting Lake wetland is low.(4)From 2015 to 2018,the explanatory power of GDP,monthly average temperature,the proportion of primary industry in GDP and per capita GDP to the landscape stability of Dongting Lake wetland is strong,and the explanatory power is greater than 0.3.In the period of 2019-2020,the explanatory power of monthly average temperature,GDP,elevation and monthly average precipitation on the landscape stability of Dongting Lake wetland is strong,and the explanatory power is greater than 0.3.In 2015,the interaction of monthly precipitation and monthly mean temperature,slope and GDP,and GDP and monthly mean precipitation had the strongest explanatory power on wetland landscape stability,with q values of 0.65.In 2016,the interaction of GDP and the proportion of secondary industry in GDP had the strongest explanatory power on wetland landscape stability,with q value of 0.77.In 2017,the interaction of GDP and monthly average temperature had the strongest explanatory power on wetland landscape stability,with q value of 0.83.In 2018,the interaction of GDP and monthly average precipitation had the strongest explanatory power on wetland landscape stability,with q value of 0.83 In 2019,the interaction of monthly mean temperature and slope has the strongest explanatory power on wetland landscape stability,with q value of 0.77.In 2020,the interaction of monthly mean temperature and elevation has the strongest explanatory power on wetland landscape stability,with q value of 0.76.