Dynamic patterns and resilience of cave-air CO₂ under tourism interferences in the Lushan National Geopark, north China

Cave-air CO₂, one of the key indicators of cave ecosystem stability and human disturbance, plays a significant role in regional carbon cycles but has long been overlooked. Existing studies have primarily focused on cave resource development and restoration, resulting in an insufficient understanding of tourism-induced CO₂ dynamics. This study conducted high-resolution monitoring in Jiutian Cave (northern China) for the first time and integrated tourist data. The results showed that the air CO₂ concentration in Jiutian Cave was lower during summer-autumn and winter-spring, with soil CO₂ identified as the primary carbon source. However, tourism activities disrupted the synergistic relationship between soil CO₂ and cave-air CO₂, causing pulsed increases in cave-air CO₂ concentration. From the perspective of cave resilience, factors such as the duration of tourist visits, the structural characteristics of different internal cave regions, and ventilation status all influence the recovery rate of cave-air CO₂ concentration.