Study On The Dynamic Changes And Driving Forces Of Alpine Wetland In The Three River Source National Park,Yellow River Source Zone

Global sustainable development is facing serious challenges due to the impact of climate warming and human activities,and in response,the United Nations Sustainable Development Summit in 2015 adopted 17 sustainable development goals,pointing out in the sixth one to protect and restore water-related ecosystems,including mountains,forests,wetlands,rivers,aquifers and lakes.As the natural ecosystem with the fastest rate of carbon accumulation on land,wetland ecosystems are important for achieving carbon peak and carbon neutrality.Based on random forest model,object-based classification,landscape pattern analysis,and correlation analysis,this study conducted scientific research on the spatial and temporal evolution and drivers of alpine wetlands in the Three River Source National Park,Yellow River Source Zone,constructed a remote sensing identification and classification method for alpine wetlands in the Three River Source National Park,Yellow River Source Zone with the help of Google Earth Engine(GEE)platform,analyzed the spatial and temporal evolution patterns of alpine wetlands,and identified the dominant drivers affecting the evolution of alpine wetlands in the Three River Source National Park,Yellow River Source Zone.The main conclusions of this study are as follows:(1)The average overall accuracy of remote sensing identification and classification of alpine wetlands in the Three River Source National Park,Yellow River Source Zone from 1991 to 2020 was 0.85,and the average Kappa coefficient was 0.80.Sentinel-2 remote sensing images had higher remote sensing recognition and classification accuracy than Landsat 8 remote sensing images because of the red-edge band.Meanwhile,the addition of radar data could effectively improve the remote sensing recognition and classification accuracy of alpine wetlands.And the random forest classification model had higher accuracy compared with the object-based classification.In addition,the importance of the classification features obtained by using the random forest classification model indicated that elevation was the most important classification feature affecting the remote sensing identification and classification accuracy of alpine wetlands in the Yellow River Source National Park.(2)From 1991 to 2020,the area of alpine wetland in the Three River Source National Park,Yellow River Source Zone decreased from 470,200 hectares in 1991 to423,300 hectares in 2020,the area of river wetland decreased by 20,900 hectares,the area of lake wetland increased by 6900 hectares,the area of marsh wetland decreased by 7600 hectares,and the area of marsh meadow decreased by 25,100 hectares,which gradually gathered and distributed to the central region in space.(3)From 1991 to 2020,the annual precipitation in the Three River Source National Park,Yellow River Source Zone increased at a rate of 3.01 mm per year,while the precipitation during the warm season increased at a rate of 1.27 mm per year.The annual average temperature increased at a rate of 0.029℃per year,and the warm season average temperature increased at a rate of 0.028℃per year.The annual potential evapotranspiration increased at a rate of 0.48 mm per year,while the potential evapotranspiration during the warm season increased at a rate of 0.20 mm per year.In summary,in the Three River Source National Park,Yellow River Source Zone was in the warm–humid climate trend.(4)Soil moisture is the primary driving force affecting the changes in alpine wetland area in the Three River Source National Park,Yellow River Source Zone from2000 to 2020,The soil moisture increased at a rate of 0.00127 m~3/m~3 per year.Followed by annual average temperature,warm season potential evapotranspiration,warm season precipitation,warm season average temperature,annual potential evapotranspiration,and annual precipitation.Population density had a negative impact on the alpine wetland area in the Three River Source National Park,Yellow River Source Zone from2000 to 2020,while the population density decreased at a rate of 0.00423 people/square kilometer per year.(5)The future forecast results show that by 2035,the area of various types of alpine wetland in the Three River Source National Park,Yellow River Source Zone will increase,and grassland is the main land use type transformed into alpine wetland.