Research on the evaluation of mountain ecological environment quality based on the perspective of supply and demand of ecosystem services

Global environmental changes, combined with various human activities, pose a significant threat to the availability of ecosystem services, which may ultimately fail to meet the increasing demands of populations. Therefore, scientific assessment of regional ecological environment quality has become an urgent scientific research topic. Based on this, this study assesses the supply and demand of ecosystem services from 2000 to 2018. A human activity intensity index was constructed, and a four-quadrant analysis model is employed to couple the supply and demand of ecosystem services with human activities, thereby exploring the ecological quality of the environment. The research results are as follows: (1) from 2000 to 2018, the remaining amount of ES was relatively large; four types of ESs are in surplus. (2) Significant variation in human activity levels is observed spatially, decreasing from the east to the west. Urban areas with high population density primarily host elevated activity levels, whereas regions characterized by lower activity are typically found in colder alpine areas. (3) The environmental conditions throughout a large area are typically advantageous; however, 13.64% of the pixels and 20 counties display inadequate eco-environmental quality. In recent years, considerable improvements in this quality have been achieved because of the execution of ecological engineering projects. (4) 91% of the pixels indicate a low-risk classification, primarily located in the western high-altitude sections. Conversely, areas classified as high risk constitute 7.42% and are chiefly influenced by the disparities in economic development among different regions. Increased human activity is increasingly likely to negatively influence the environment and increase ecological threats. By investigating this interaction, we can gain critical insights that are essential for the effective regulation and management of mountain ecosystems.