The harmonious development of the ecological environment and the economy is extremely important to achieve regional ecological construction and sustainable development. To properly assess the status of the harmonious development of the ecosystem and the economy, this study constructed an improved ecosystem services value (ESV) and eco-economic harmony (EEH) model to analyze the coordination relationships between the ecosystem and the economy in this region, based on Landsat TM/OLI data of Anxi County in 1999, 2009, and 2019. The results were as follows. (1) Significant changes in land- use occurred in Anxi County between 1999 and 2019. While grassland, cultivated land, and water bodies decreased by 22.91%, 36.82%, and 8.18%, respectively, other land-use types expanded including construction land (206.10%), garden land (56.39%), forest land (10.37%), and unutilized land (90.43%). (2) The ESV decreased by CNY 41.02 billion during this period, with the largest contribution from forest land and the most important service function being regulating services, and mountainous townships made a great contribution to the total ESV. (3) The eco-economic system of Anxi County was at an inharmonic level. The evaluation model produced more favorable results, especially at the township scale, which is highly sensitive to economic policy. This can provide scientific evidence for inter-regional ecological compensation and sustainable development while providing reference and inspiration for similar areas around the world to carry out relevant research.

Studying the applicability of the SWAT model in the source area of the Yellow River is helpful for the comprehensive management of water resources and hydrological cycles in the source area of the Yellow River. The SWAT monthly runoff simulation model was constructed using DEM data, land use data, soil data and meteorological station data in the source area of the Yellow River, and the parameters were calibrated using the SUIF-2 algorithm in SWAT-CUP2012, with determation coefficients R² and Nash-Sutcliffe efficiency coefficients (NSE). The results show that the fit between the monthly runoff simulation process and the measured runoff process in the source area of the Yellow River is close. The R² and NSE were 0.77, 0.76, 0.90, and 0.89 in the model calibration period 2000∼2009 and verification period 2010∼2013, respectively. This shows that the SWAT model simulates the monthly runoff process of the source area of the Yellow River satisfactoriy, that is, the SWAT model e has good applicability in the Yellow River source area.

To obtain a scientific understanding of the spatial and temporal patterns of agricultural ecoefficiency (AEE) as well as its influencing factors in Fujian Province, effective recommendations were provided to promote agricultural green development. The Super-SBM model with undesired output was employed to assess AEE, and the GTWR model was used to analyze the main factors influencing AEE based on data from nine prefecture-level cities in Fujian Province spanning from 2000 to 2020. There are three conclusions to be drawn: Firstly, the AEE of Fujian Province has increased from 0.340 in 2000 to 0.971 in 2020, but it has not yet reached the efficiency frontier due to excessive input of agricultural factors and carbon emissions. The development of AEE across regions is unbalanced with a wide gap between them. Secondly, from a spatial correlation perspective, global correlation of AEE in Fujian Province showed random distribution while local agglomeration existed to varying degrees. Thirdly, AEE in Fujian Province was influenced by various driving factors that changed significantly over different periods and exhibited obvious regional differences. In summary, the AEE of Fujian Province has shown overall improvement; however, its effectiveness remains limited. The disparities among cities are evident, necessitating the formulation of differentiated strategies for agricultural ecological development to enhance regional synergistic driving forces and improve regional AEE.

Rapid urbanization has seriously interfered with the carbon sink function of forests, and has even led to an increased risk of forest carbon imbalance. It is important to explore the regional carbon compensation mechanism and zoning optimization path based on forest carbon accounting to achieve the “dual carbon” goal and sustainable forest management in Fujian Province. Based on remote sensing and GIS technologies, this study measured forest carbon emissions and carbon sequestration of each county in Fujian Province, revealed spatial and temporal evolution of forest carbon budget during the period from 2000 to 2020, and calculated carbon compensation value of each county, so as to realize scientific accounting of forest carbon compensation, and then explored zoning optimization pathways of forest carbon compensation in Fujian Province. The results show the following: (1) From 2000 to 2020, the forest carbon budget in Fujian Province as a whole showed a spatial pattern of “coastal deficit, northwest surplus”, with obvious spatial imbalance characteristics, and showed a high growth trend of net carbon sequestration. (2) From 2000 to 2020, the average carbon compensation rate in Fujian Province was 7.92, and compensation zones were mainly concentrated in the economically developed southeast coastal regins such as Fuzhou, Quanzhou, Xiamen, Zhangzhou, and Putian, while compensation-receiving zones were mainly concentrated in northwestern mountainous areas such as Nanping, Ningde, and Longyan, which had a high forest coverage rate. (3) From 2000 to 2020, there was a significant difference in growth rates of compensation amounts and compensation-receiving amounts in Fujian Province. The cumulative increase in compensation amounts was 322.82%, while the cumulative increase in compensation-receiving amounts was only 17.5%. (4) Based on priority levels, the counties in Fujian Province are classified into six types of forest carbon compensation zones—potential compensation zones, secondary compensation zones, priority compensation zones, potential compensation-receiving zones, secondary compensation-receiving zones and priority compensation-receiving zones—and optimization paths of differentiated zones are explored.

Exploring the simulation and optimization pathways of ecological networks under multiple scenarios is conducive to ensuring ecological security and achieving high-quality development of urban agglomerations. In this study, the PLUS model was utilized to perform spatial simulations of land use change in the urban agglomeration in the middle reaches of the Yangtze River under four alternative scenarios: natural development (ND), ecological protection (EP), cropland protection (CP), and economic development (ED). By integrating the InVEST and MSPA models with circuit theory, ecological networks and ecological security patterns were constructed within a dual-temporal framework of “past and future”. On this basis, ecological management zoning and corresponding optimization pathways were explored across different scenarios. The results indicated that: (1) During the period 2000–2020, land use in the urban agglomeration in the middle reaches of the Yangtze River was dominated by cropland and forestland. (2) Multi-scenario land use types showed divergent evolutionary trends. The ND scenario maintained the historical pattern; the EP scenario increased ecological land by 1.2%; the CP scenario expanded cropland by 11.74%; and the ED scenario raised construction land by 33.78%. (3) During the two decades, the habitat quality and landscape configuration of the study area remained largely stable. The connectivity of ecological corridors across scenarios ranked as EP > ND > ED > CP. Consequently, ecological networks under multiple scenarios and an ecological security pattern characterized by “three barriers, four corridors, three belts, and multiple nodes” were established. (4) The urban agglomeration was classified into three major categories of ecological priority conservation zones, namely ecological source conservation zones, ecological source coordination zones, and ecological source restoration zones, along with five levels of ecological management zones. Based on this classification, zoning optimization strategies were explored under multiple scenarios. This study provides valuable guidance for ensuring ecological security and implementing differentiated, multi-level ecological management strategies in the urban agglomeration in the middle reaches of the Yangtze River.