Balancing environmental benefits and accessibility for national park buffer zones in China

National parks conserve species and ecosystems while offering educational, scientific, cultural, and recreational opportunities, which should extend beyond park boundaries to benefit surrounding areas. However, existing research often neglects both the recreational value of national parks and the development of their surrounding buffer zones. Using Baishanzu National Park, China, as a case study, this research proposes an integrated framework to assess the synergies and trade-offs between environmental effects and accessibility within a 30-km buffer zone. Results show that: (1) The park produces significant cooling and air purification effects, with a cooling intensity of 2.57 °C and a PM2.5 reduction of 0.97 µg/m³, extending over 2,474.08 km² and 3,039.43 km², respectively. (2) Favorable environmental conditions are mainly concentrated in Jingning and Qingyuan counties. (3) Accessibility analysis indicates relatively stable travel times and developed road networks, yet high travel costs persist, with the best accessibility observed in central Longquan and eastern Jingning counties. (4) Spatial autocorrelation analysis reveals a significant negative relationship between environmental effects and accessibility (Binary Moran’s I = − 0.392). Synergies (high-high clusters) occur near the northern park entrance, while trade-offs (high-low/low-high clusters) are found in southeastern and western buffer zones. Quantitative comparisons suggest that improving accessibility by 21.4% in high–low areas and enhancing environmental quality by 17.8% in low–high areas could mitigate spatial mismatches. These findings provide scientific support for differentiated buffer-zone planning for national parks and inform strategies to enhance their recreational potential while promoting sustainable development.