Many tree fern taxa have a skirt, an encircling structure of persistent dead fronds or stipes around the growing crown at the top of the trunk. Page and Brownsey (1986) hypothesised that the function of these skirts was to protect tree ferns against damage from large epiphytes, hemiepiphytes, and climbing plants. Tree fern trunks provide both suitable establishment surfaces for a range of woody epiphytes and hemiepiphytes in New Zealand, as well as attachment surfaces for climbing rātā (Metrosideros spp.).
Tree fern trunks provide establishment surfaces and habitat for a range of plant taxa including many understorey shrubs and canopy trees. The importance of these habitats for augmenting forest biodiversity and woody plant regeneration processes has been the subject of conjecture but has not been robustly assessed.
The quantitative composition of ground and epiphytic vegetation, consisting predominantly of bryophytes, is recorded from a lowland stand of climax beech-podocarp forest at Jacksons Bay, South Westland, together with briefer accounts from five pre-climax transitional stands. A survey of epiphylls, indicators of very high humidity, is included and comparisons are made with stands on Secretary Island and Stewart Island