Contrasting elevational patterns of soil and root-associated fungal communities highlight host-driven filtering in Quercus wutaishansea forests.

The role of plant hosts in shaping root-associated microbial communities remains a central question in ecology, particularly in the face of changing environmental conditions. While considerable attention has been paid to soil microbial diversity, the interactive dynamics between plant individuals and soil microbial pool during root-associated fungi establishment across environmental gradients remain poorly understood. In this study, we explored the elevational variation in the diversity of soil and root-associated fungal communities of Quercus wutaishansea across ten elevational belts (1020 m-1770 m above sea level (asl)) on Dongling Mountain, Beijing, China. We found that root-associated fungal communities exhibited significantly increased alpha diversity with elevation (P < 0.05), whereas soil fungal communities showed no clear elevational trends (P > 0.05). Despite substantial variation in the soil fungal pool, the composition of root-associated fungal communities remained notably stable, suggesting a strong host filtering effect (P < 0.05). Compared with hump-shaped Sim and decreasing Morisita β-diversity of soil fungi as elevation increased (P < 0.05), the β-diversity of root-associated fungi did not exhibit a consistent elevational pattern nor mirror soil fungal β-diversity. These results suggest that, beyond environmental filtering, Q. wutaishansea plays an active role in shaping its root fungal community by selecting compatible fungal partners according to its physiological needs across altitudes. The findings reveal a significant and variable plant selectivity in the recruitment of microbiomes across different elevations, offering novel insights into plant-microbiome interactions within forest ecosystems in response to climate change.