Spatiotemporal Multi-scale Habitat Selection Of Red-crowned Crane In Yancheng Coastal Wetland And Its Influencing Mechanism

The red-crowned crane is an endangered species in the world and a national first-class protected animal.It is a large wading bird that depends on wetlands for survival.The habitat selection of red-crowned cranes is limited by spatial and temporal scales and has the characteristics of multi-scale selection.The coastal wetland in Yancheng,Jiangsu Province,is the world's largest wintering ground for red-crowned cranes.In recent years,affected by rapid regional economic development,intense reclamation of coastal wetlands,increasing human disturbance,huge changes in vegetation communities and obvious changes in hydrological and soil environment,the habitat of red-crowned cranes has been seriously lost and degraded.Therefore,based on the theories of landscape ecology,geography and environmental science,a systematic study was carried out by using field investigation,GPS tracking,remote sensing and GIS technologies,as well as maximum entropy and generalized additive model methods.The characteristics and changes of habitat selection of red-crowned cranes were analyzed at regional,landscape and home range scales,as well as temporal scales,such as diurnal and seasonal scales,to reveal the driving mechanism of landscape pattern factors.In addition,the impacts of landscape process factors on habitat selection of red-crowned cranes were revealed from the perspectives of hydrology and soil.Finally,a multi-scale habitat restoration model was proposed.The research can provide scientific basis for the conservation and restoration of red-crowned crane population and habitat.The main conclusions of the study were as follows:(1)Regional habitat selection of red-crowned cranes is affected by habitat type change,land use/cover disturbance,and wind power disturbance.During the period from 1984 to 2017,great changes in regional land use resulted in a direct decrease in the total habitat area of red-crowned cranes from 971.1 to 200.1 km~2,with a loss of 79.4%.At the same time,habitat fragmentation was serious,spatial isolation was enhanced,and functional connectivity decreased by 95.6%.The contribution percentage of land use disturbance in each period was 54.1%-75.7%.In addition,habitat type change was the second most important factor affecting habitat selection,contributing 25.2%-43.5%.Wind power disturbance was also an important influencing factor,contributing 12.0%-26.3%.(2)Habitat selection at landscape scale was influenced by landscape pattern factors such as habitat type,area coverage,and road disturbance,and the influencing factors have spatial and temporal multi-scale differences.Red-crowned cranes mainly inhabit natural wetlands in the core area.The suitable habitat area of red-crowned cranes varied from day to night:the suitable habitat area of day was 8.6-30.0 km~2,the suitable habitat area of night was 7.3-16.1 km~2,and the suitable habitat area decreased from spring to winter.The habitat selection of red-crowned cranes was the result of the interaction of influencing factors,and there were significant scale differences:the food factor(area coverage rate of Scirpus mariqueter)at the scale of 200-500 m was very important,and it was the most important driving variable for habitat selection at night and day in different seasons,with a contribution rate of 57.8%-72.2%.In daytime habitat selection,the hidden and disturbance factors at 200-500m scale were relatively important,which showed the scale selection characteristics of selecting Phragmites australis habitat,avoiding road and Suaeda salsa habitat.In night habitat selection,the 50 m scale water source and safety factor(area coverage rate of pond)were of relatively importance,and their contribution rate accounts for 6.5%-26.2%.(3)Interaction between hydrology and soil was a landscape process factor that affects habitat selection of red-crowned cranes.Tidal creeks were important driving factors for habitat selection of red-crowned cranes.The interaction related to the distance of the tidal crevice was the most important influencing variable,and showed certain threshold characteristics:the habitat suitability of the red-crowned crane decreased rapidly when the distance from the tidal creeks was 1000-1200m;Within 1000-1200 m of the tidal creek,the habitat selection of the red-crowned crane responded to the distance of the pond and the soil salinity.The interaction between hydrology and soil had seasonal and diurnal differences.In spring and summer,red-crowned cranes choose habitats with medium to low and moderate soil salinity near ponds and tidal creeks.In autumn and winter,red-crowned cranes selected habitats with moderate or higher soil salinity near ponds and tidal creeks.The day-night difference was mainly reflected in the driving effect of the interactive variable of pond distance.Red-crowned cranes mainly selected the night habitat within 50-200 m from the pond,while the influence of pond was weaker in the day habitat selection.Red-crowned cranes selected the day habitat within 400 m from the pond in winter and spring,and the influence was not obvious in other seasons.(4)Based on the study of multi-scale influencing factors of habitat selection,a comprehensive habitat restoration model was proposed from the structural and functional aspects.Firstly,the habitat spatial network structure was constructed at the regional scale.Key nodes and connected corridors were the key points of regional structural restoration,and priority should be given to the restoration of extremely important nodes in the core area and the surrounding buffer zone as well as the important links of the southern corridors of the region.Secondly,the restoration model of the internal habitat pattern was proposed,including area restoration,vegetation coverage restoration,and habitat combination allocation.It was suggested to set up a restoration area of 63.25 km~2 inside the core area,and restore the habitat area of Phragmites australis,Scirpus mariqueter and Suaeda salsa at a area ratio of 1:1:2.The coverage of Phragmites australis habitats should be managed,and the"high coverage","medium and high coverage"and"medium and below coverage"habitats were restored according to the area ratio of 3:4:3.The"mosaic habitat pattern"was constructed,including the"Phragmites australis-Scirpus mariqueter mosaic pattern"for the day habitat and the"Phragmites australis-Scirpus mariqueter-pond mosaic pattern"for the night habitat.Finally,based on the interaction of landscape pattern,process and function,some suggestions for restoration of habitat function were proposed.Reasonably removing Spartina alterniflora and Phragmites australis,opening tidal channels and restoring healthy intertidal water and salt processes were the key to restoring habitat function.