Dendroid forms and fans were most numerous on tree trunks and understorey trees, whereas compact forms and tall turfs were most numerous in the forest canopy and restricted in the understorey to the crowns of young trees (zone U3). These results confirm that species with exposed life forms are more successful in the

understorey, where they are well-protected against radiation and desiccation and where their growth form helps them to access as much light as possible. In contrast, species with compact life forms can better cope with warmer and drier circumstances such as those found in higher canopy strata (León-Vargas et al. 2006). Lastly, branch structure such as diameter and inclination of twigs and branches, is an important factor determining the composition of learn more epiphytic bryophyte assemblages of the forest canopy (Yamada 1975–1977; Wolf 1996; Holz 2003). The high number of tall turf species in the canopy may

be due to the presence of horizontal braches and crutches, which provide optimal conditions for the see more establishment and growth of tall turfs. Vertical substrates characteristic for the understorey of the forest appear to be generally unsuitable for these species. In contrast, dendroids, tails and fans, which are generally only narrowly attached to the substrate, are less dependent on horizontal substrates as anchoring places and abound in the forest understorey. Conclusions We found significant differences in epiphytic bryophyte diversity on tree trunks and young trees in the understorey versus the crowns of the trees; nearly 48% of all click here species were restricted to the forest canopy trees. Our study was the first to include understorey trees in the analysis of vertical distribution of epiphytic bryophytes using standardized sampling methods. Although no more than 9% of the recorded species were only found on young trees of the understorey, diversity of dendroid and fan-like species was highest on trunks and understorey trees, and would have been underestimated or neglected when the understorey would have been excluded. The importance of young understorey trees as a habitat for epiphytes was earlier demonstrated for vascular

epiphytes by Krömer et al. (2007), who ID-8 found that more than 20% of total species diversity would have been missed when this habitat as well as shrubs would not have been sampled. The results indicate that conservation strategies aimed at preserving the variety of tropical habitats and recognition of suitable indicator species, should consider the understorey trees in addition to the mature canopy trees. Our study once more reveals the importance of undisturbed rainforests with a dense, closed canopy and a well-shaded, cool and moist understorey for the preservation of high levels of biodiversity (Sporn et al. 2009). Disruption of the forest canopy would inevitably risk levelling these habitat differences and pose a threat to the unique bryophyte flora of the forest understorey (Gradstein 2008).