Background and aims: Filmy ferns ( Hymenophyllum , Hymenophyllaceae) depend on moist microsites, but the factors determining their habitat assemblage remain unclear. This study investigated how five habitat variables-stem orientation (N, S, E, W), phorophyte species, presence of climbers, diameter at breast height (DBH), and canopy cover-affect the composition of filmy fern communities in a temperate forest.<br /> M&M: The four orientations of 120 trees (480 microsites) were sampled along a transect drawn through the centre of the forest. At each microsite, the presence or absence of ferns was assessed up to a height of 2.3 metres on the trunk. Data analysis was performed using PERMANOVA with 10000 permutations followed by multiple comparisons to detect differences in fern composition between forophyte species.<br /> Results: DBH (Pseudo-F = 21.617; p < 0.001) and host tree species identity (Pseudo-F = 4.123; p < 0.001) significantly influenced the fern assemblages. Multiple comparisons revealed significant differences (pseudo-T, p < 0.05), especially between Eucryphia cordifolia, which had a more diverse fern composition, and Laureliopsis philippiana, with a simpler composition.<br /> Conclusions: The physical and biotic characteristics of the host tree seem to be key to the structuring of filmy fern communities. Other environmental factors may be less important or may be masked by homogeneous sampling conditions, insufficient sample size or anthropogenic disturbances.