Forest Change And Its Impact On The Habitat Of Yunnan Snub-nosed Monkey(Rhinopithecus Bieti) In Yunling Region

Yunnan snub-nosed monkey(Rhinopithecus bieti)is an endemic and endangered species in China.R.bieti is mainly distributed in Yunling mountain region between Jinsha River and Lancang River in Hengduan Mountains.Forest ecosystem dominated by spruce-fir forest is main habitat of R.bieti.However,land use change and forest degradation have exacerbated habitat loss and habitat fragmentation,posing a major threat to R.bieti conservation.Therefore,it is important to identify the spatiotemporal change processes of key ecosystem types in Yunling region,and to assess their impacts on the habitat of R.bieti.It not only plays an important role in the protection of R.bieti,but also has significant impact in maintaining biodiversity hotspots in Hengduan Mountains.At present,all populations of R.bieti are distributed in Yunling region,mainly including Mangkang County of Tibet Autonomous Region,Deqin County,Weixi County,Yulong County,Lanping County and Yunlong County of Yunnan Province.We selected above six counties as the study area in Yunling region.Based on the Google Earth Engine(GEE)platform,we explored the impacts of various classification methods and multi-source classification features on the accuracy of ecosystem classification in 2019.Secondly,Using Land Trendr algorithm combined with NDVI(Normalized Difference Vegetation Index,NDVI)time series spectral curve,we realized the sample migration from 2019 to 1990,and completed the ecosystem type identification in 1990.We used Land Trendr algorithm and Normalized Burn Ratio(NBR)spectral index to identify the forest disturbance in the study area during 1991-2019,and analyzed the variation characteristics of forest disturbance.Finally,based on the data of ecosystem types distribution,the distribution points of R.bieti and other environmental factors in 1990 and 2019,we used Max Ent model to simulate the spatiotemporal changes of R.bieti's habitat and analyzed the response of R.bieti's habitat to forest disturbance.Main research conclusions are as follows:(1)Using the random forest classification algorithm and multi-source classification features can significantly improve the classification accuracy.Finally,the overall classification accuracy was 94.13%,and the Kappa coefficient was 0.93 in 2019.The classification accuracy of random forest algorithm was better than that of support vector machine and classification and regression tree algorithm.Based on multi-spectral bands,spectral index and texture features,the introduction of terrain features such as altitude and slope could significantly improve the classification accuracy,and the backscattering features had a relatively small improvement in the classification accuracy.Through sample migration,we obtained the training samples in 1990 and finally realized the ecosystem classification in 1990.The overall accuracy was 91.77%,and the Kappa coefficient was 0.91.(2)Forest disturbance was identified in the past 30 years,the overall accuracy of forest disturbance identification was 89.84%.The total area of forest disturbance was876.17 km~2,among which spruce-fir forest disturbance mainly happened before 2000,while the pine forest,oak forest and other forest types showed a large inter-annual fluctuation.As a whole the protected areas of R.bieti could restrain forest disturbance,and the establishment and conservation level upgrading of nature reserve could effectively restrain forest disturbance.Hot spots of forest disturbance were mainly distributed at the south of the study area,including the surrounding townships of Yunling nature reserve and the northern townships of Yunlong County.The clod spots of forest disturbance were mainly distributed at the north of study area,including the surrounding townships of Mangkang Hongla mountain nature reserve.(3)In the past 30 years,different suitable habitat types of R.bieti were declined,among which the most suitable habitat decreased by 20.58 km~2,the moderate suitable habitat decreased by 35.45 km~2,and the low suitable habitat decreased by 104.19 km~2.At present,there are still some conservation gaps for R.bieti,and conservation efficiency of protected areas needs to be improved.Forest disturbance had significant impact on the habitat of R.bieti,the disturbed habitat area for R.bieti was 156.34 km~2,which were mainly composed of moderate and low suitable habitats.And most of region would become unsuitable habitat under the influence of forest disturbance.