Quantifying multidimensional urbanization responses around national nature reserves in China

Alongside rapid urbanization in China, a large number of protected areas have been established. However, their relationships with multiple dimensions of surrounding urbanization pressure remain insufficiently understood. In this study, we examined 322 national nature reserves in China and used GDP, population density, impervious surface, and PM2.5 concentration data from 2000 to 2020 to quantify the spatiotemporal dynamics of urbanization around reserves. The results show that all four urbanization variables exhibit pronounced distance gradients within 5 km of reserve boundaries, with spatial heterogeneity being more prominent in areas immediately adjacent to reserves. Growth rates of GDP and impervious surfaces were generally lower in areas surrounding terrestrial animal reserves, larger reserves, and reserves with higher forest cover. Reserves with higher internal proportions of impervious surfaces and natural landscapes showed higher surrounding GDP growth but lower impervious surface expansion. PM2.5 concentrations and population density tended to be higher around reserves with greater internal water-body proportions, while lower values of these two variables were observed around reserves located in Yunnan, Sichuan, Chongqing, and Inner Mongolia. Overall, these findings highlight the need for differentiated planning and management strategies around nature reserves that consider reserve attributes, regional context, and multiple dimensions of urbanization pressure.