Spatial pattern and screening framework of national park agglomerations in the Greater Shangri-La region, China

National park agglomerations are a collection of multiple types of regional protected areas, and these agglomerations are of great importance for giving play to the functions of various ecosystem services in protected areas, establishing ecological corridors, and improving the level of regional ecological protection. The Greater Shangri-La region is located at the junction of Sichuan, Yunnan, and Tibet Provinces in China and is in the transition zone of two major biogeographical regions, the Palearctic and Indo-Malay regions, with numerous and rich types of protected areas. This study summarizes the practice of combined national park protection globally, analyzes the spatial pattern of 87 protected areas in the Greater Shangri-La region, proposes a framework for the spatial identification and screening of national park agglomerations based on ecoregions, and establishes the ecosystem, landscape type, cultural heritage, spatial distance, and protection management used as indicators for the screening framework of national park agglomerations. Five national park agglomerations, namely, Three Parallel Rivers, Shaluli Mountain-Daxue Mountain, Southeast Tibetan Plateau, Liangshan Mountain, and Panxi Rift, are present in this area, covering 52 protected areas, with characteristics of spatial agglomeration, diverse types, and natural and cultural heritage-rich features. These results help improve the environmental protection system in the Greater Shangri-La region and better promote the construction of national park agglomerations in other places of the world