## 4 Discussion
For example, some scholars established the nonlinear quantitative relationship between economic development and environmental quality through the environmental Kuznets curve (EKC). Still, this method can only reveal the results of the coupling and fails to explore the causes of how they form a mutual coupling [2; 56]. Therefore, this study differs from the previous ones in that it establishes a framework for assessing the population-urbanization-ecological environment by combining the coupling coordination degree model and the decoupling index. The innovation of this study is that, firstly, this study combines the practicality of each index, proposes a Pressure-State-Response-Service ecological environment index system, and combines the population census index and urbanization index to measure the relationship between humans and the land under the new type of urbanization more comprehensively. Secondly, this study combines the coupling coordination degree model with the decoupling index to comprehensively and systematically understand the coupling coordination degree relationship and decoupling relationship of the population-urbanization-ecological environment and explores the human-land configuration effects of population change, urbanization level, and ecological environment change across time and space, thus providing a basis for the differentiated formulation of urban development policies. Finally, this study quantified the contribution value of various indicators for alleviating environmental pressure, deepened the understanding of the coupling interaction of the population-urbanization-ecological environment, and provided a scientific basis for diagnosing the inconsistency of the internal mechanism of the population-urbanization-ecological environment. This research can provide a new research perspective for discovering internal problems related to new urbanization and can also provide China's quantitative data and development path reference for the United Nations Sustainable Development Goals. At the same time, this study provides a methodological reference for future research on regions with the same regional characteristics, such as the study of ecology and environment, spatial coupling of water resources, and global trade transfer. However, this study only clearly illustrates the relationship between the population, urbanization, and ecological environment from the typical angle of human activities. Therefore, it has the following limitations: (1) future studies should fully recognize the complexity and comprehensiveness of human activities, land change, and ecological impacts and construct more comprehensive measurement indicators; (2) the spatial scale of this study is province-based, and subsequent studies need to consider spatial transformation and scale effects so that the research questions can be more focused on local reality. (3) The research data have certain limitations. This study did not consider the impact of Earth observation data, land use and urbanization simulation results, mobility data, etc. Subsequent research is needed to integrate more extensive data in order to more realistically present the relationship between urbanization and natural systems.