Quantitative assessment of ecological conservation effectiveness and spillover effects of China's first group of national parks

National parks conservation effectiveness and its spillover effects is vital for the planning, establishment, assessment, and management of national parks. In this study, we used threshold regression and propensity score matching to quantitatively assess the conservation effectiveness and spillover effects of China's first group of national parks on habitat quality, human modification and forest cover. The results showed a significant heterogeneity in the conservation effectiveness and spillover effects across the national parks. Most conservation indicators in the inner areas of the national park achieved excellent conservation effectiveness, with no <7.51 %. Unlike within national parks, spillover areas exhibited weaker conservation effectiveness, with a minimum of 2.70 %. Moreover, negative spillover effects caused by spillover transfer were observed. Threshold phenomena were prevalent for the negative impacts of population density and road density on spillover effects, and crossing them increased negative impacts by 10 % to 437 %. Differences in the spatial distribution of anthropogenic pressures have resulted differences in conservation effectiveness and spillover effects across national parks. This prompts us to comprehensively account for ecological indicators and anthropogenic pressures in the allocation of conservation measures. This study offers theoretical guidance and methodological references for assessing conservation effectiveness, setting protection goals and improving the allocation of conservation measures in national parks.