Study On Landscape Pattern Of Poyang Lake And Habitat Selection Of Satellite Tracking Siberian Crane During The Wintering Period

Poyang Lake has a unique hydrological environment,climatic conditions and abundant food resources.It is an important wintering ground for water birds such as Siberian Cranes,and is of great significance to the protection of migratory birds on the East Asia-Australia migration route.The habitat conditions of Poyang Lake directly affect the number and distribution of Siberian Cranes.In recent years,the habitat of Siberian Cranes has shifted from lake wetlands to farmland habitats,and more people have been paying attention to the wintering habitat changes of Siberian Cranes.This study selects Landsat 8 remote sensing image data of 12 periods of Poyang Lake during the high water period and low water period in 2014-2018,and uses object-oriented random forest classification method to compare different ages and phase of Poyang Lake land use/cover type changes and landscape pattern characteristics.Five Siberian Cranes were selected for the ring and satellite trackers.According to the satellite tracking data obtained,the distribution hotspots,activity regularity and activity area of Siberian Cranes in Poyang Lake were analyzed and compared in 2014-2018.Based on the Maxent model,using the Siberian Crane distribution data and environmental factor data,the suitability evaluation model of the Siberian Crane habitat was established,and the importance distribution of each environmental factor and the response to the habitat selection of the Siberian Crane were analyzed and the interior of Poyang Lake protective vacancy area was obtained.These are conducive to a more comprehensive and effective protection of the Siberian Crane population.(1)Comparing the land use/cover type of Poyang Lake in 2014-2018: Although the phases are the same,the landscape types of Poyang Lake in different years still have a large shift.During the high water period of 2014-2018,The lake and marsh moved to each other.The marsh show a tendency of first positive transfer and then negative transfer.In the same phase(10/11 months),in 2014-2017,the landscape type almost completely shifted.The same phase(December),2015-2016,the lake and Marsh2 were mainly transferred to mudflat and marsh1.In 2016-2017,Marsh2 was mainly transferred to Marsh1.Marsh1 refers to aquatic and marsh herbaceous plants including Carex L.?Nymphoides?Heleocharis and so on.Marsh2 is a freshwater marsh with herbaceous species such as Phragmites australis(Cav.)Trin.ex Steud?Triarrhena lutarioriparia L Liu.In the same phase(February),2015-2016,a large shift occurred,the area of the mudflat and marsh2 increased significantly.(2)The landscape pattern index indicates that the area of the lake and the percentage of the landscape in the high water period of 2014-2018 are inversely proportional to the marsh.2016 and 2017 compared to 2014 and 2015,the area of marsh are small and the shape of the patchs is more regular,the distribution of the patchs is more dispersed,the landscape is single.In the low water period of 2014-2018,the area of lake and mudflat are basically inversely proportional,Marsh1 and Marsh2 are basically inversely proportional.In the same phase(10/11 months),2017 compared to 2014,the area of mudflat and marsh decreased,the shape of patchs was more regular,the distribution of the patchs is more dispersed and the landscape diversity and uniformity is smaller.In the same phase(December),2016 and 2017 compared to 2015,the area of mudflat and marsh2 increased.The mudflat and Marsh1 are closer to each other,the fragmentation of landscape increased and landscape shape tends to be regular and the number of patch types is smaller.In the same phase(February),2016 and 2018 compared to 2015,and the area of Marsh1 was significantly small.With the increase of the year,the shape of the marsh1 patchs is more regular and the distance of marsh1 patchs is more dispersed,marsh2 is the opposite.The change of landscape pattern of Poyang Lake in 2014-2018 is driven by natural hydrological rhythms and human factors.(3)In 2014-2018,there is a clear difference in the selection of Siberian Cranes in Poyang Lake.The habitats of the Siberian Crane were transferred from wetland to farmland.The home range gradually migrated to the south and east.The movement changed from regular to irregular.(4)The Maxent model simulates the three wintering habitat selections of the Siberian Cranes: the habitat heterogeneity increases with the increase of the year.During the three wintering periods,the NDVI value and PRI value in the low water period,the NDVI value in the high water period,the land cover type,the mudflat patchs density and landscape percentage have greater gains in establishing the model.With the increase of years,the contribution of the lake and Paddy field of the land use/cover types to the habitat selection of Siberian Cranes increased.The highand lowarea of the marsh in the high water period are the reasons for the gradual decrease in the impact of the NDVI value in the high water period on the habitat selection of the Siberian Cranes.After the NDVI value and PRI value of low water period reach a certain value,it is no longer suitable for the distribution of Siberian Cranes,indicating that moderate vegetation cover in the habitat is beneficial to attract the distribution of Siberian Cranes.With the increase of the landscape percentage of mudflat and the decrease of mudflat patchs density,the habitat suitability of Siberian Crane increased,but the growth rate was quite different.This is proportional to the size of the mudflat area and inversely proportional to the number of mudflat in the three wintering periods.During the three wintering periods,the consideration of the distance to dams is gradually increased.The average precipitation in 2015 is greater than that in 2014,and the appropriate precipitation will contribute to the increase of the Siberian Crane habitat suitability.(5)The sub-suitable habitat of the Siberian Cranes in Poyang Lake is increased and suitable habitat is decreased.This reflects the adaptation of Siberian Cranes to sub-suitable habitats and human disturbance to some extent.Protection vacancies of Siberain Cranes in Poyang Lake are mostly located in adjacent areas of wetlands and paddy fields with large human disturbances.The protection scope of reserves should be expanded or new protected areas should be established to strengthen protection.At the same time,we should pay attention to the current suitable habitats and the new suitable habitat areas,which is of great significance for the more comprehensive and effective protection of the Siberian Crane population.