Study On The Function Of Water Conservation And Soil Conservation In Qilian Mountain National Park

Water and soil resources are the basic resources for human survival,and quantitative assessment of water conservation and soil conservation functions is the basis for rational use of resources,maintenance of ecological stability,and promotion of ecological protection and construction.The Qilian Mountain National Park is one of the important ecological function areas in China,and the functions of water conservation and soil conservation are its main ecological functions,so it is of great practical and long-term significance to carry out quantitative studies on these two functions.Based on the InVEST model and 3S technology,this study explored the spatial and temporal changes of these two functions in Qilian Mountain National Park during 1988-2019,analyzed the influence of land use,climate,soil,vegetation,and topography on the two functions,and discussed the correlation between the two functions,and finally made a typological classification based on their spatial distribution.The main conclusions of the study are as follows.（1）The land use types of Qilian Mountain National Park during 1990-2018 are mainly grassland,unused land and forest land,and grassland and unused land account for more than 80% of the total area.The interconversion of each land use shows an increase in the area of forest land and grassland and a decrease in the area of unused land and watershed,and forest land is mainly converted from grassland and unused land,grassland is mainly converted from unused land,and watershed is mainly converted to unused land.（2）The water conservation of the park fluctuates between 1988 and 2019,with more in the southeast and less in the northwest.32 years,the area of water conservation increased（89.95%）was 12 times larger than that of the area of decrease（7.27%）.The water conservation capacity of different types of land is woodland >grassland > unused land > water,and the total water conservation amount is grassland > woodland > unused land > water;precipitation is significantly and positively correlated with water conservation amount,which is the main factor to enhance water conservation amount;under different topographic conditions,there are some differences in the change patterns of regional water conservation capacity and total amount.（3）Spatially,the soil conservation capacity of the park gradually increased from northwest to southeast;temporally,the soil conservation capacity generally fluctuated and increased,and the area with increased soil conservation amount（84.43%）was much larger than that with decreased amount（1.39%）.The soil retention capacity of different land types in order is: forest > grassland > unused land > water,and the total soil conservation amount in order is: grassland > forest > unused land > water.On the altitude gradient,the changes of soil conservation capacity and soil conservation amount are roughly divided by 2750 m and 4000 m,respectively.On the gradient of slope,the changes of soil conservation capacity and soil retention amount are roughly divided by 65° and 25°,respectively.The soil conservation capacity of the Luvic Chernozems soil is the largest,and the soil conservation amount of the Gelic Leptosols soil is the largest.（4）The water conservation and soil conservation functions were generally positively correlated in time and space during the study period,but the spatial correlation gradually weakened,and with some variability in the temporal correlation in different regions.