| Maintaining the sustainability of ecosystem functions is of great significance to regional and even global sustainable development and ecological security.Tightening resource constraints,serious environmental pollution,and ecosystem degradation have severely restricted the sustainable development of my country’s social economy.To this end,the Chinese government has put forward an important strategy to comprehensively promote"ecological civilization construction"and"ecological protection and high-quality development in the Yellow River Basin."The Hehuang Valley is located in the ecologically fragile area in the upper reaches of the Yellow River Basin—the ecological environment is fragile and plays an important ecological function,which ecological status is related to the ecological security of the middle and lower reaches of the Yellow River and even the whole country.However,in the past few decades,the significant increase in human activities and the significant warming of the climate have had a profound and significant impact on its ecological environment.Therefore,we should study the past,present and future trends of ecosystem services in the Hehuang Valley,as well as their temporal and spatial differentiation laws,reveal the trade-off and synergistic relationship between different services and their scale effects,and clarify the contribution of different land types to ecosystem services to the overall ecosystem services,which has important theoretical value and practical significance for scientific and rational development of river basin ecological management and restoration.In this paper,based on the land use/cover change of the Hehuang Valley in the past20 years,the InVEST model was used to quantitatively evaluate the water production,carbon storage,soil conservation,and habitat quality in 2000,2005,2010,2015 and2020.On this basis,the temporal and spatial variation characteristics of various ecosystem services and their temporal and spatial differentiation laws were explored,the trade-off and synergistic relationship of ecosystem services,important functional areas and their scale effects were identified,and the trade-off and synergy laws of four ecosystem services were explored.At the same time,the PCA model is used to identify important areas of ecological functions as the basis for restrictive setting of ecological scenarios.In addition,the optimal geographic detector model is used to identify the dominant driving factors,and the MGWR is used to detect its spatial influence range,reveal its driving force mechanism,and finally couple CA,The Markov,PLUS and InVEST models predict the ecosystem services and trade-off synergies at the global and watershed scale of land use/cover change in the Hehuang Valley in 2030,and finally propose regional ecosystem management strategies.Provide reference for management,land use and ecological management.The main results are as follows:(1)Grassland is the largest and most widely distributed land use/cover type in the study area,accounting for about 56%of the total area of??the Hehuang Valley;From2000 to 2020,the land types with the largest area changes were grassland,cultivated land,forest land and construction land,and the grassland degradation trend was obvious.Due to the implementation of the policy of returning farmland to forest and grassland,the area of forest land increased;the conversion comparison between various types Frequent,especially the mutual conversion between grassland,forest land,cultivated land and unused land and the conversion of water area to cultivated land are more significant.In the past 20 years,the land use cover/type combination of each secondary watershed is relatively stable.According to the distance from the main and tributaries of the river,the main land types of each secondary watershed basically show the spatial distribution characteristics of"construction land-arable land-grassland-forest land"from near to far,which is also related to the typical landform features of"three mountains and two valleys"in the Hehuang Valley.In the mountainous areas,forest land and grassland are mainly distributed.The higher the altitude,the higher the proportion of forest land area,while the valley land(that is,each secondary watershed,here mainly refers to the Huangshui watershed and the main stream from Longyang Gorge to Lanzhou)The area is mainly distributed in water area,construction land,cultivated land and grassland.(2)The ecosystem services of the Hehuang Valley in the past 20 years have the law of spatial heterogeneity,and have spatial dependence and differences.Forest land,grassland and unused cultivated land are the four services with relatively strong capabilities.Among them,forests and grasslands are located in the three mountains(Lenglongling in Qilian Mountains,Daban Mountain in Qilian Mountains,Nanshan in the south)—the high-value aggregation area of ecosystem services,and the low-value ecosystem services in the two valleys(Huangshui Valley and Yellow River Valley).Over the past 20 years,due to human engineering,ecosystem services have gradually improved.Using the InVEST model,the water production service,soil conservation service,carbon storage service,and habitat quality service in the Hehuang Valley were evaluated,and the global and local spatial autocorrelation relationships were measured.The global spatial autocorrelation mainly reflects high-high aggregation and low-low Aggregation coexists,and there is a spatial differentiation law.The water production volume and water production depth in 2000,2005,2010,2015 and 2020 are:3.12×10~8m~3(88.63mm),4.49×10~8m~3(127.47mm),3.84×10~8m~3(109.16mm),3.26×10~8m~3t(92.76mm)and 6.40.×10~8m~3(181.92mm),soil retention and modulus are:282.80.62×10~8t(8027.99t·ha·a),282.76.34×10~8t(8026.78t·ha·a),283.15.95×10~8t(8038.02t·ha·a),283.16×10~8t(8038.21t·ha·a),283.18×10~8t(8038.03 ha·a),the carbon storage is 232.11×10~6t(65.89ha·a),232.86×10~6t(65.82ha·a),234.85×10~6t(66.67ha·a),234.43×10~6t(66.55ha·a),234.22×10~6t(66.49 ha·a);habitat quality:0.6516,0.6516,0.6481,0.6484,all showing a fluctuating small rise.In the spatial distribution pattern,the high value is distributed in the three mountains(Lenglongling,Daban Mountain in the Qilian Mountains,and the Nanshan area in the south),and the low value is distributed in the two valleys(Huangshui Valley,Yellow River Valley)and the desert area in the north.(3)The relationship between the four ecosystem services in the Hehuang Valley was basically stable during the study period,and the synergistic relationship between the various service functions of soil conservation,habitat quality,water production,and carbon storage in the whole area was dominated by synergy;There is an obvious scale effect—the trade-off relationship of ecosystem service functions in each watershed is different from that of the whole watershed,and also among the secondary watersheds—each ecosystem service function as a whole shows obvious watershed differences and regional laws.(4)Based on the PCA and SOM models,we divide the ecosystem service functions of the Hehuang Valley into two ecosystem service-dominant functional areas-area I is the dominant functional area for carbon storage and habitat maintenance services,and area II is for water production and soil conservation services.Dominate the ribbon.On the basis of functional zoning,we propose 1 extremely important unit of ecological protection,4 core units of individual ecological service functions,and 4 units of ecological service improvement,which provide the basis for limiting development boundaries for ecological scenario setting.(5)The prediction of future land use/cover change in Hehuang Valley shows that under the ecological protection scenario,the forest and grassland areas are more than the natural development scenario and the economic development scenario.Under the three land use/cover forecast scenarios,there are obvious differences in the change space and change status of ecosystem services.Based on the three land use/cover prediction scenarios,it is found that the relationship between the four ecosystem services at the global scale and the watershed scale is basically moderated,the global scale is in a state of coordination,and some are in a state of trade-off.state of existence.The high-quality development of the Yellow River Basin and the construction of ecological civilization in Qinghai Province need to pay special attention to the importance of ecosystem services,but at the same time,we should also weigh the complex relationship between ecosystem services and regional human well-being based on different temporal and spatial scales—in order to strengthen policies at different levels connection ability. |
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