Vertical patterns of epiphytic bryophyte diversity in a montaneNothofagusforest in the Chilean Andes

Structural heterogeneity of trees influences epiphyte distributions in a northern temperate rainforest

“…There were clear trends within the branch zones that showed turnover in species composition from the inner to the outer crown, which were driven by changes in branch diameter and moss depth, suggesting that canopy humus influences epiphyte distributions. These results are supported by those in tropical rainforests that show epiphyte distributions are influenced by branch diameter and the presence of canopy humus (Freiberg, ; Hietz & Hietz‐Seifert, ; ter Steege & Cornelissen, ; Woods et al., ) as well as in other temperate rainforests that showed that epiphyte distributions are influenced by the presence of canopy humus or “duff” (Hofstede et al, ; Mellado‐Mansilla et al., ) and location on branches (Pike et al., ). This suggests that species in the inner and mid‐branch zones, such as the moss Rhytidiadelphus loreus and the lycophyte Selaginella oregana , establish on large surface areas, and either require thick moss mats because of the underlying canopy humus, which can provide nutrients or water (Aubrey, Nadkarni, & Broderick, ; Freiberg, ; Woods et al., ), or create the thick moss mats themselves by their growth patterns.…”

“…The unique composition of epiphytic species in the lower trunk is consistent with another study that examined epiphyte distributions up to 5 m on A. macrophyllum trees at varying sites in British Columbia and found turnover in species composition with height (Kenkel & Bradfield, ). Height was also found to influence epiphyte communities in other temperate forests (Bates, ; Coxson & Coyle, ; Hofstede et al, ; Lyons, Nadkarni, & North, ; Mellado‐Mansilla et al., ; Oksanen, ). Canopy cover was significantly higher in the lower trunk zones than in all other tree zones and declined with increasing tree height, which was also found in beech trees in Japan (Omura, Nishihara, & Hosokawa, ), and in an old‐growth Douglas fir and Western Hemlock Forest in Southern Washington State (Parker, ).…”

“…We found that a single tree can host up to 13 different epiphyte species, many of which were dominant in particular areas within the trees. Variations in structural features, more than microclimatic features, influenced the distribution of epiphytes, which adds to the growing body of literature on the importance of habitat heterogeneity for epiphyte species diversity and distribution (Hofstede et al, ; Mellado‐Mansilla et al., ; Pike et al., ; Woods et al., ). In northern temperate rainforests, large bigleaf maple trees house the greatest biomass of epiphytes of all tree species in the forest, a biomass that can be four times that of their host tree (Nadkarni, ).…”

“…Canopy cover was significantly higher in the lower trunk zones than in all other tree zones and declined with increasing tree height, which was also found in beech trees in Japan (Omura, Nishihara, & Hosokawa, ), and in an old‐growth Douglas fir and Western Hemlock Forest in Southern Washington State (Parker, ). This suggests that the species that dominated in the lower trunk zones ( Leucolepis acanthoneura and Metaneckera menziesii ) are likely shade tolerant, while those that dominated in the outer branch zones may have higher temperature or light tolerances (Mellado‐Mansilla et al., ; Turetsky, ). Kenkel and Bradfield () argued that light and the availability of water influences epiphyte distributions in A. macrophyllum as varying heights and inclinations of the trunk can influence moisture and light availability.…”

“…We used the metaMDS function in the vegan package in R to run our NMDS (Oksanen et al, 2010). A Monte Carlo test was performed with 1,000 iterations in order to determine to what degree the NMDS ordination differed from random; the stress level of the Monte Carlo test had to be greater than the stress level of the NMDS analysis to be considered different from random (McCune, & Grace, 2002). We fit the mea-…”