Effects Of Land Use Change On Habitat Distribution Of Wintering Red-crowned Crane In Northern Jiangsu Province

The red-crowned crane(Grus japonensis),a globally endangered species,is under first-grade state protection in China.The dynamic changes in population have been widely concerned.Jiangsu province is the main wintering area of wild red-crowned cranes in China.In recent years,the range of wintering habitat of the red-crowned crane is constantly squeezed and the area of the overwintering region gradually diminishing,because of the accelerated process of urbanization and the increase of land use intensity.All of this has serious threat to the survival of red-crowned cranes.In this study,the northern of Jiangsu province was selected as a study area.Based on landscape ecological principles,with the help of RS and GIS technology,this paper systematically analyzed the dynamic changes in population size and habitats distribution of wintering red-crowned cranes since 1980s.Thus the study reveals the effects of land use changes to the wintering habitats of the red-crowned crane.The text made some advice on protection of wintering red-crowned cranes.The main conclusions are as follows:(1)The number of overwintering populations of red-crowned cranes in Northern Jiangsu has changed greatly since 1980s,and the overall trend is decreasing.In the 80s and 90s of last century,the natural ecological environment was better.The number of overwintering populations of red-crowned cranes in the north of the Yangtze River in Jiangsu was increasing year by year.At the end of 1999,the population of overwintering populations of red-crowned cranes was the largest in the north of Jiangsu,up to more than 1100.In the twenty-first century,with the development of social and economic development,the overwintering habitat of red-crowned cranes was seriously damaged and the number of its population declined.By 2015,the number of overwintering populations of red-crowned cranes was only about five hundred or six hundred,and the population loss was serious.(2)The distribution of overwintering populations of red-crowned cranes in North Jiangsu gradually narrowed,and the number of habitat distribution points was lost year by year.In the winter of 1980s,red-crowned cranes were widely distributed in inland lakes around the middle and lower reach of the Yangtze River in Jiangsu and coastal tidal wetlands.The habitats of the red-crowned cranes were large and the ecological environment was good.By 90s,there were no documents about the distribution of the overwintering populations of red-crowned cranes around the inland lakes in Northern Jiangsu.The wintering Red-crowned cranes transfer to coastal area of Binhai County,Sheyang County,Dongtai County,Dafeng County,Rudong County.In twenty-first century,with the development of coastal area,the habitat scope of red-crowned cranes in coastal wetlands was.gradually reduced.By 2015,the overwintering period of the red-crowned crane was almost exclusively in the core area of the Yancheng reserve.It shows that the distribution of overwintering habitat of red-crowned cranes is lost seriously.The number of overwintering habitat distribution points of red-crowned also decreased from 17 in 1983 to 1 in 2015.(3)From 1980s to 2015,the situation of land use in Northern Jiangsu has also changed greatly.It is mainly manifested in a large reduction in the area of natural wetlands,such as marshland,lake marshes,and paddy field.And the large expansion of the area of non-wetland or semi-artificial wetland such as construction land,aquaculture pond,salt field and so on.The impact of land use change on overwintering habitat of red-crowned cranes is mainly reflected in the influence of wintering habitat types and the influence on the network structure of wintering habitat of red-crowned cranes.The change of land use leads to the serious loss of the lake marshes and coastal wetland.The results show that the land-use change reduces the whole area of lake marshes,the average patch area is slightly increased,and the mean nearest neighbor distance of the patch is gradually reduced.However,the total area of coastal wetlands is not only serious,but the average patch area also shrinks,and the average distance between patches increases.The patches become more discrete.These are not conducive to foraging and inhabiting of the red-crowned cranes during wintering.In a word,the area of the overwintering habitat of red-crowned cranes is decreasing,and it becomes fragmented,and the environment of overwintering habitat is deteriorating as a whole.The impact of land use change on the overwintering habitat network of red-crowned cranes made the connectivity of the habitat network decrease,and the network structure is fragmented,so that there is no network connection.(4)Habitat area and habitat quality are closely related to population dynamics of red-crowned cranes.Therefore,protection of overwintering populations of red-crowned cranes must strengthen the protection of overwintering habitats.At present,the most important thing is to strengthen the protection of the existing core habitat,the prohibition of the development of the core habitat and the interference of human activities.On this basis,there is a selective restoration of potential habitat patches to alleviate the survival pressure of the Red-crowned Cranes in the core habitat.