Spatial variability of phyllosphere fungal assemblages: genetic distance predominates over geographic distance in a European beech stand (Fagus sylvatica)

► We quantified the spatial variability of phyllosphere fungal assemblages in beech. ► The highest variability is at the smallest spatial scale, between leaves. ► At the stand scale, the structure is explained by the genetic variation of trees. ► The effect of genetic variation on associated assemblages can be studied at low cost.