| The products and services provided by ecosystem are not only closely related to the current economic and social development,but also affect the future survival and well-being of mankind.Quantitative assessment of ecosystem services and analysis of the influencing factors of ecosystem services are the basis for protecting the natural environment and taking into account good ecological conditions and economic development.At present,the ecological and environmental problems in arid and semi-arid areas in China are extremely serious.How to protect ecosystem services scientifically and reasonably based on regional characteristics is a situation that must be considered in the overall development of these areas.Ningxia Hui Autonomous Region is located in the northwest arid and semi-arid transition area,and in the upper reaches of the Yellow River Basin.The outline of ecological protection and high-quality development planning for the Yellow River Basin shows that the protection and utilization of the Yellow River Basin has become one of the key undertakings of national strategic concern.As a leading area for watershed ecological protection and high-quality development,Ningxia is an important window to show the coordinated development of the West and even the whole country.Taking Ningxia Hui Autonomous Region as the research area,this paper analyzes the land use change in Ningxia in 2010,2015 and 2020 through the land use transfer matrix,and clarifies the structural change of land use;Secondly,four ecosystem functions,including water production service,soil conservation,wind prevention and sand fixation,and carbon fixation,were selected to explore the spatio-temporal evolution of ecosystem services at the provincial and municipal levels,and to measure the comprehensive level of ecosystem services;Finally,the factor detection and interaction detection modules of the geographical detector are selected to detect the factors that affect the function of the regional ecosystem.Finally,policy suggestions are put forward in order to provide reference for the arid and semi-arid areas and other provinces and cities in the Yellow River Basin,promote the longterm development of the arid and semi-arid areas and the sustainable utilization of resources,and promote the coordinated governance of the Yellow River Basin.The specific research results are as follows:(1)Land use status and changes.The grassland area in Ningxia is the largest,mainly distributed in Zhongwei city and Wuzhong City.The water area is the smallest,mainly distributed in Yinchuan city and Shizuishan city.Cultivated land is concentrated in Yinchuan plain and areas along the Yellow River.From 2010 to 2020,the construction land area increased significantly,the grassland area decreased significantly,and the conversion between grassland and cultivated land was the largest.(2)The spatiotemporal changes in ecosystem functions.From 2010 to 2020,the total volume of water production in the water production function showed a trend of “first decreasing and then increasing”,with an overall increase.The spatial distribution showed an increasing trend from north to south.The average annual water production per unit area is 15.02 mm,and the average annual total volume of water production is 778 million cubic meters.Guyuan City has the largest water production,while Shizuishan City has the smallest water production.Cultivated land and grassland are the land use types with the highest total water production volume in Ningxia,while unused land has the lowest water volume.From 2010 to 2020,the total amount of soil conservation in the soil conservation function first decreased and then increased,and in 2020,it was higher than in 2010.The average annual total amount of soil conservation was 656 million tons.In terms of spatial distribution,it is high in the north and south while low in the middle,distributed in a strip shape along the mountain.Guyuan City has the largest amount of soil conservation,while Yinchuan City has the smallest total amount of soil conservation among various administrative regions.Grassland,as a land type,has the greatest contribution to soil conservation in the entire region,reaching 54.17%.From 2010 to 2020,the amount of wind proof and sand fixation per unit area and the total amount of wind proof and sand fixation in the function of wind proof and sand fixation first decreased and then increased,but in general,2020 was lower than 2010,and the average annual quality of wind proof and sand fixation was 17.6124 million tons.In terms of spatial distribution,the high value areas are distributed in the middle,East and south,and the low value areas are distributed in the north and West.The high value areas tend to shift to the East and south over time.Wuzhong has the largest amount of windbreak and sand fixation,while Yinchuan has the least.Grassland is the land use type that contributes the most to windbreak and sand fixation,accounting for 48.68%.The average annual wind break and sand fixation rate is 0.675,and the variation is small.From 2010 to 2020,the total carbon storage in the carbon sequestration function showed a downward trend,with an average annual decline of 33 million tons,and the multi-year average was 250.3 million tons.In terms of spatial distribution,the high-value areas of carbon sequestration are mainly distributed in the eastern and Northern Helan Mountains and the southern Liupan Mountains,which are dotted and linear in each city,while the low-value areas are concentrated in the northwest and Yinchuan plain.The carbon storage of Wuzhong City ranks first in Ningxia.Grassland is the largest carbon pool in Ningxia,accounting for 53% of carbon sequestration.From 2010 to 2020,the comprehensive level of ecosystem services in Ningxia declined slightly,only 4.2%.Jingyuan County and Jinfeng district are respectively the highest and lowest values of the comprehensive level of ecosystem services.The area proportion of important and above levels has increased,indicating that the overall situation of ecosystem services in Ningxia is improving.(3)Detection of factors affecting ecosystem function.The factor detection results of the geographical detector show that the single factor with the highest degree of spatial heterogeneity affecting water production function,soil conservation function,wind prevention and sand fixation function,and carbon fixation function are annual precipitation,terrain gradient,annual precipitation,and annual average temperature,respectively;In general,the influence of natural factors on ecosystem function is dominant.The results of interaction detection show that the explanatory power of the interaction of two factors on various ecosystem functions is more obvious than that of single factor,which also reflects the complexity of the process of spatial differentiation of ecosystem services and factor interaction. |
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