Urban land expanded closer to protected areas in China: a three decade investigation over 2622 protected areas

Various types of protected areas (PAs) are important for biodiversity conservation and essential for the 2050 Vision for Biodiversity. Rapid urban expansion affects the effectiveness of PAs in many ways. However, we still lack a clear understanding of the spatial relationship between urban expansion and different types of PAs in China during the last 30 years. Here, we analyzed the spatiotemporal changes in such relationship based on the boundaries of 2622 terrestrial PAs, as well as local Moran's and the Kruskal-Wallis H test during the period of 1992-2020 at the national, regional and provincial scales. The results showed that the number of PA threaten by urban expansion at the national scale fluctuated over time (10 to 80), while the median of the nearest distances between PAs and urban built-up areas decreased from 80.4 km to 2.6 km. At the regional scale, the PAs in east China were more affected by urban expansion than the ones in west China, with higher number of threatened PAs and closer distance between PAs and urban built-up areas. More importantly, non-national PAs were more severely affected by urban expansion than national PAs, and the proportion of threatened non-national PAs is 92.5% in 2020. Thus, future planning and management should place more attention to the non-national PAs that are severely affected by urban expansion. We investigate spatial relation between urban expansion and 2622 protected areas in China.Rapid urban expansion in recent years has posed a serious threat to PAs.Non-national PAs are more severely threatened than the national PAs.