Elevation modulates the effects of tourism disturbance on soil fungal and bacterial communities in a cold-temperate montane forest

Tourism activities in mountain forests can alter belowground ecological processes, yet how soil microbial communities respond to the combined effects of elevation and tourism disturbance remains unclear. Here, we investigated the diversity and composition of soil fungal and bacterial communities across different tourism disturbance intensities along an elevational gradient in the Kanas Lake forest area. Our results showed that both fungal and bacterial richness increased with elevation, while the effects of tourism disturbance on richness were modulated by elevation, with the lowest richness observed under high disturbance at the lowest elevation sites. Fungal richness was primarily associated with soil organic carbon (SOC), whereas bacterial richness was mainly related to soil water content (SWC) and total nitrogen (TN). Elevation significantly affected both fungal and bacterial community composition, whereas the interaction between elevation and tourism disturbance affected only fungal community composition. Compositional variation in both groups was related to SWC and SOC, with stronger correlations for fungi. Significant responses among dominant fungal taxa were detected only at the genus level, with Mortierella declining with increasing elevation and Solicoccozyma peaking at the middle elevation. Among dominant bacterial taxa, Pseudomonadota and Actinomycetota exhibited non-linear disturbance responses, with their highest mean relative abundances occurring under moderate disturbance, whereas Chloroflexota varied mainly with elevation. These findings suggest that areas at lower elevations and close to tourist trails are particularly sensitive to tourism disturbance, highlighting the need to reduce trampling and maintain soil habitat stability to support sustainable tourism management in mountain forest ecosystems.