Urbanization is an important factor affecting the pattern of regional ecological security. Clarifying the relationship between urbanization and ecosystem services can provide decision-making references for promoting ecological protection and high-quality development in the Middle Yellow River. Based on the analysis of the spatio and temporal patterns of urbanization and ecosystem services in the Middle Yellow River from 2000 to 2018, the study uses the coupling coordination degree model to analyze the spatio-temporal characteristics of the coupling relationship between urbanization and ecosystem services in the study area. The results show that between 2000 and 2018, the comprehensive urbanization level increased by 72.24%, and the spatial distribution was generally "high in the south and low in the north", with economically developed counties decreasing outward. Grain production, water resource conservation, soil conservation and carbon sequestration services all showed an increasing trend in different spatial distribution trends. Generally, the degree of coupling coordination between grain production, water resource conservation, soil conservation and carbon sequestration services and comprehensive urbanization level is on the rise, but the degree of coupling coordination in the Fenhe-Weihe Plain is low, while that in economically developed counties is high.

Based on the calculation of the ecosystem service supply, demand and coordination degree in the Yellow River Basin, we comprehensively analyzed the co-variation trend of land spatial pattern and coordination degree of supply-demand in this basin. Then, correlation analysis and quantile regression were used to analyze the influence of various land spaces on the coordination degree of supply-demand, and its regional heterogeneity. The results showed that: (1) Land spatial pattern, and supply and demand of ecosystem services showed significant spatio-temporal differentiation. The upper and middle reaches of the river and the lower reach are areas with densely distributed and significantly increased productive land and living land from 2000 to 2015. The increase in supply of ecosystem service was consistent with the distribution of cultivated land and forest land, and that in demand of ecosystem service was consistent with the distribution of population density and construction land. (2) The spatio-temporal change of the coordination degree was affected by the evolution of land spatial pattern. The influence of the land spaces on the coordination degree of supply and demand was different under different coordination levels, and there was significant regional heterogeneity in different regions. (3) According to different land spaces that had an impact on the coordination degree, different areas should rationally lay out land space and formulate development policies to promote effective ecosystem management.

The Yellow River Basin is an important ecological barrier and economic zone in China, and its upstream water-conserving areas play a decisive role in the sustainable ecological development of the Yellow River Basin. Therefore, scientific coordination of urban and rural development and reasonable delineation of urban growth boundary (UGB) are of great significance for ecological protection and high-quality urban development in the Upper Yellow River Basin. This paper takes Linxia, a typical prefecture-level city in the upper reaches of the Yellow River, as the research object, and assesses its ecological quality based on land use and related remote sensing data using remote sensing ecological index (RSEI) and ecological sensitivity analysis. On this basis, the future urban growth boundary development with and without ecological quality assessment conditions is analyzed in combination with CA-Markov comparison. The results show that: (1) From 2005 to 2015, the overall ecological environment of the study area was poor and decreased year by year, and the ecological quality (RSEI) result dropped to the lowest (0.38) in 2015. Meanwhile, the ecological sensitivity changed from moderate to low sensitivity. (2) The urban expansion area increased by 6.04 km², and the scale of urban construction land in 2030 obtained by CA-Markov simulation was 95.88 km², which exceeded the planned area by 3.2 km², and the urban expansion was not effectively restrained. (3) Simulation of RSEI-CA-Markov shows that the urban construction land in 2030 is 90.36 km², which is smaller than the planned government planning area of 3.3 km², and meets the requirements of urban sustainable development. Based on this, the designated UGB has stronger urban management capabilities. The delineation of UGB in the ecologically fragile area in the Upper Yellow River is conducive to guiding and realizing sustainable urban development, which can also provide reference for the sustainable development of other ecologically fragile cities in China.

Based on the analysis of the coupling mechanism of ecological protection and high-quality development, the provincial unit is taken as the research unit to evaluate the coupling coordination degree of ecological protection and high-quality development of the Yellow River Basin, compared with the Yangtze River Economic Belt. Finally, the panel VAR model is used to quantitatively analyze the interactive response relationship between ecological protection and high-quality development in the Yellow River Basin. The main conclusions are as follows: (1) During the study period, both the ecological protection index and the high-quality development index of the Yellow River Basin showed an increasing trend, and the overall pattern of the middle and lower reaches was higher than that of the upper reaches. (2) The coupling coordination degree of ecological protection and high-quality development in the Yellow River Basin showed an overall increasing trend. Among them, the coupling coordination degree from 2003 to 2011 was less than 0.5, which was an antagonistic stage; in 2012-2017, the coupling coordination degree is between 0.5-0.7, which belongs to the run-in stage. The metropolis in the Yellow River Basin presents a spatial pattern of downstream > middle reaches > upstream, with the highest coupling coordination between Shandong and Shanxi at the provincial level, and the lowest coupling coordination between Ningxia and Qinghai. (3) The ecological protection index of the Yellow River Basin is slightly higher than the national average. The high-quality development index and the coupling coordination degree are lower than the national average. The ecological protection index of the Yellow River Basin in the early stage (2003-2009) is lower than that of the Yangtze River Economic Belt, while it is higher in the later period (2010-2017). The high-quality development index and coupling coordination degree are lower compared with the Yangtze River Economic Belt in all the years. (4) Both the ecological protection and high-quality development of the Yellow River Basin have positive progressive effects and inertial development characteristics, and their effects on themselves are declining year by year, and the degree of attenuation of high-quality development is more obvious. The ecological protection and high-quality development of the Yellow River Basin play a positive role in promotion, but due to the overall low level of ecological protection and high-quality development and uneven internal development, the mechanism of action of the two is not significant.

The ecological environment in the upper reaches of the Yellow River is fragile, and ecological and environmental problems such as soil erosion and land degradation continue to threaten the health of the ecosystem and the quality of human settlements. In order to explore the safety status of the ecological environment in the ecological function area in the upper reaches of the Yellow River, this article quantitatively analyzed the spatio-temporal distribution of ecosystem service value and ecological risk index based on land use data in 2000, 2010 and 2018, with the help of ecosystem service models and ecological risk models, and built four types of ecological divisions through z-score standardized methods. The results show that: (1) During the study period, various land use types changed to varying degrees. Among them, construction land increased most significantly due to the transfer of cultivated land and grassland, with an increase area of 118 km² and a growth rate of 46.36%. (2) The overall service value of the study area has a small degree of change, the ecosystem services are mainly regulating services and the grassland provides the highest value. High service value areas are mainly distributed in areas with high vegetation coverage such as the southwestern part of Linxia prefecture and Zhuoni county. (3) The ecological risk level of the study area is generally low, showing the characteristics of "high in the north and south, but low in the middle". The low and low ecological risk areas account for more than 76% of the total area. (4) Little changes have taken place in the four types of ecological zoning, indicating that the ecological zoning is in a relatively stable state of development. The continuity of the spatial distribution of different ecological zones is poor, among which high ecosystem service value-high ecological risk area (I) is the most typical. Constructing ecological zoning through ecosystem services and ecological risks (value-risk) can provide a theoretical basis for coordinating the relationship between humans and land in the region and clarifying future development directions.