The slope aspect is one of the most critical topo-graphic factors in mountainous areas.Little is known,how-ever,about the effect of the aspect on the ectomycorrhizal(ECM) fungal community.Additionally,we know very little about the composition of ECM fungal communities associ-ated with Quercus variabilis,which is widely distributed in East Asia.In this study,we compared the richness,commu-nity composition,and exploration types of ECM fungi asso-ciated with Q.variabilis between predominantly south- and north-facing slopes in the Taihang Mountain,North China for the first time.DNA was extracted from the root tips of Q.var-iabilis,and Illumina MiSeq sequencing was used to identify ECM fungi.In total,168 operational taxonomic units belong-ing to 28 genera were detected,and the ECM community was found to be dominated by Russula,Inocybe,Tomentella,Scle-roderma,and Cortinarius.Compared with the north-facing slopes,the ECM communities on the south-facing slopes had higher diversity.The community composition and explora-tion types were directly affected by the slope aspect.Also,the aspect-induced edaphic variables,such as total phosphorus,total nitrogen,total potassium,pH,and soil water content,were important sources of variation in ECM fungal rich-ness and distributions of exploration types.Different genera tended to be distributed in various slope aspects.Cenococ-cum,Genea,and Clavulina were significantly enriched in north-facing slopes,while Geopora,Helvelosebacina,Scle-roderma,Gyroporus,Astraeus,Boletus,Ticholoma,Hebe-loma,Cortinarius and unclassified Thelephoraceae were more abundant in south-facing slopes.Hydrophobic ECM fungi were obviously enriched in the south-facing slope,but there was no statistical difference between hydrophilic among the south- and north-facing slopes.Our study deepened our knowledge of the aspect-driven variation in ECM fungal communities associated with Q.variabilis.