Analysis of ecological carrying capacity using a fuzzy comprehensive evaluation method

With the rapid development of the economy, environmental issues have become increasingly prominent and pose a threat to the sustainable development of human society. Maintaining the integrity of ecosystems and limiting human activity are prerequisites for sustainable economic development. Therefore, fully understanding the regional ecological conditions and related influential factors is important for promoting regional sustainable development. It is of great practical significance to study the ecological carrying capacity (ECC) from multiple perspectives. In this paper, Shannon entropy theory, a fuzzy comprehensive method and an analytic hierarchy process (AHP) are used to provide reasonable weights for ECC evaluation modelling by combining subjective and objective weights. Furthermore, based on ecological resilience and ecological pressure, a comprehensive system of evaluation factors is established for ECC assessments. For this study in Yunyang County in the Three Gorges Reservoir area of China, the following fifteen factors were selected: slope, land use, the land stress index, the habitat quality index, the water network density index, vegetation coverage, the geological hazard index, annual total rainfall, annual total temperature, the population density index, the proportion of construction land, the economic development index, the road network density index, the steep slope reclamation rate and the proportion of agricultural land. Additionally, an obstacle degree model was used to explore the response relationship between the regional ecological quality and the corresponding influential factors and to extract the major factors that affect the quality of the ecological environment. The results show that the area with a very low comprehensive evaluation rating is 119.54 km2, accounting for 3.30% of the study area, including Bayang Town, Shuangjiang Street and Qinglong Street, and the area with a low comprehensive evaluation rating is 519.29 km2, accounting for 14.34% of the study area. The main factor that influences the environmental quality of the study area is the economic development index, and the obstacle degree frequency is higher than 80%. Additionally, the steep slope reclamation rate, land stress index and proportion of agricultural land also have considerable impacts on the ECC of Yunyang County, with obstacle degree frequencies of 61.90%, 61.90% and 52.38%, respectively.