Land Use/Cover Change And It's Effects On The Habitat Of Black-Grus Nigricollis In Dashanbao,Yunnan

With the global change and intensification of human impacts,habitat change has become a serious threat to wild animals.Dashanbao National Nature Reserve of Yunnan is the most important winter habitat for Black-Necked Crane,a national key protected animal.Taking Dashanbao Nature Reserve as the research area,the land use /cover change(LUCC)in the year from 1992 to 2016 was studied based on the Landsat images.Habitat quality change of the Black-Necked Crane was evaluated by the analytic hierarchy process(AHP)and the habitat suitability index model(HSI).The results are as follows:(1)At present,cultivated land in Dashanbao Nature Reserve was 4209hm2,accounting for 21.9% in the whole region.Forest land was 3071hm2,accounting for16%.Shrub land had an area of 937hm2,accounting for 4.8%.Grassland was9865hm2,accounting for 51.4%.The area of the marsh meadow was 278hm2,accounting for 1.5%;Building and Road had 501hm2,accounting for 2.6%.Water body was 337hm2,accounting for 1.8%.Grassland is the dominant land use type in research area,followed by the cultivated land.The sum of the two types area accounts for 73.2%in the reserve.(2)Suitable habitats of Black-Necked Crane were effected by land use type.The area of most suitable habitat was 189hm2,only accounting for 1% of the total area.The suitable habitat's area was 6863hm2,accounting for 35.7%.Sub-suitable area was9101hm2,accounting for 47.4%.And the unsuitable habitat area is 3056hm2,accounting for 15.9%.The most unsuitable habitat was woodland,Building and Road,and the adjacent areas of residential.The main reason was that the black necked crane likes open area with great view of the terrain,so the natural enemies could be found in time.Food shortage in those area was also another reason.Additionally,human activities had strong effects on the habitat suitability.(3)During the period of study,the largest area change happened to cultivated land,which continuous reduction,and reduced 1788hm2 in total,mainly because that cultivated land changed into grassland.Forest land increased by 559hm2,and the areaof shrub land increased by 620hm2 year by year,mainly due to the conversion of cultivated land to forest and barren hills.Grassland reduced by 148hm2 from 1992 to2008,increased by 472hm2 from 2008 to 2016,and increased by 324hm2 in total,which was transformed from cultivated land,and transformed to woodland,building and roads at the same time.Marsh meadow increased by 48hm2 from 1992 to 2000,reduced by 90hm2 from 2000 to 2016,and reduced by 42hm2 in total,mainly due to the conversion of marsh meadow and water body in different seasons.Building and roads increased year by year,and the total area increased by 229hm2.Cased by tourism prosperity in the Dashanbao Nature Reserve.Water body area increased by 98 hm2.It was transformed from grassland and marsh meadow partially.Due to the conversion of marsh meadow and water body in different seasons,besides Le Li Zhai reservoir was built.(4)Effects of LUCC on the habitat of Black-Necked Crane.During the study period,main changes of LUCC was cultivated land decreased,and the increased of woodland,grassland and water area.Among them,the reduction of cultivated land had the greatest impact on the habitat of black necked crane,which led to a food reduction and a decreased in habitat suitability of black-necked cranes.Besides,new constructed reservoir made the area of the water increased 98hm2,while implemented fence protection to marsh meadow increased it's production,and grassland added could also provided food for black-necked Crane to a certain extent.On the whole,the most suitable habitat of Black-Necked Crane was reduced by 86hm2,0.4%.In addition,the area of forest land,shrub land and cultivated land increased,which resulting in the range reduction of Black-Necked Crane foraging activities,made the sub suitable and unsuitable habitat area increased by 42hm2 and 16hm2 respectively.In general,LUCC in Dashanbao caused the area of the most suitable reduced,the area of sub suitable and unsuitable creased,the habitat suitability of Black-Necked Crane decreased.(5)The purpose of returning farmland to grassland was to reduce human interference and protect Black-Necked Crane's habitat.However,the food provision of grassland and meadow was low,and the productivity in the alpine water body was lowalso.Main food resources of Black-Necked Crane were residual crops left in farmland.The implementation of returning cultivated land to grassland did not ameliorate the habitats or provides more food for Black-Necked Crane,on the contrary,the suitable habitat area of black necked cranes was reduced,which not conducive to the life of black necked cranes during the winter.In term of food source,cultivating land without harvesting in foraging area would provide more food for the black-necked crane.In order to improve roost sites,it was of great significance to build shallow water dams,to protect meadow and promote wetland restoration.The government should increase investment subsidies,and to reduce grazing and tourism,so as to protect the black necked crane in a fundamental sense.