Boundary delineation and grading functional zoning of Sanjiangyuan National Park based on biodiversity importance evaluations.

Recently, China advanced a policy of establishing a protected area system with national parks as the main body, and so the development of protected areas has entered a transitional period. However, to promote the coordinated development of economic construction and ecological protection of protected areas, their management needs to be more comprehensive and refined. Therefore, a more quantitative and refined spatial planning and management method for protected areas is urgently needed. This study took Sanjiangyuan National Park as the research object and considered the three biodiversity elements of species, ecosystems and landscape. The maximum entropy (MaxEnt) model, Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, and Fragstats software were used to determine the areas with highly suitable species habitat, areas of high ecosystem service value and areas of high landscape diversity. Based on these areas, Marxan software was used to calculate the irreplaceability value, identify the boundary of Sanjiangyuan National Park and clarify the gaps of the existing Sanjiangyuan National Park in the space. We suggest that at least 18,569 km2 of the eastern part of the Sanjiangyuan Region with a high irreplaceability value should be included in the existing Sanjiangyuan National Park. Moreover, the first-level zones were also classified based on irreplaceability, and the second-level functional zones were classified by K-means clustering based on the evaluation of ecological vulnerability and economic construction suitability. The first-level zones include "core conservation zones" and "general control zones", which had areas of 71,758.20 km2 (57.99%) and 51,980.13 km2 (42.01%), respectively. The core conservation zones were further zoned into primary vulnerable zones and secondary vulnerable zones. The subzones of the general control zones are multifunctional and they are tourism-grazing-living zones, grazing-living zones, tourism-living zones, tourism zones and other areas.