In tropical and subtropical forests, the forest canopy is one of the most species-rich habitats and it supports a variety of epiphytes, including many bryophytes. However, previous studies on the vertical gradient with tree height have been limited by the difficulties of canopy access. 

In a recent study published in Journal of Vegetation Science, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of Chinese Academy of Sciences used canopy cranes to sample epiphytic bryophytes along the entire vertical gradient, from tree base to outer canopy, in two bryophyte diversity hotspots of Yunnan Province, China. 

Taking advantage of the establishment of two new canopy cranes, in tropical lowland seasonal rain forest in Bubeng (21°36′N) in 2014 and in subtropical montane moist evergreen broad-leaved forest in Xujiaba (24°32′N) in 2015, researchers sampled bryophytes from 1600–2400 cm² of bark surface in 14 vertical segments in three canopy layers on 142 trees, using canopy cranes. 

They compared the diversity within and between forests by using Analysis of Variance (ANOVA). 

By recording totally 184 bryophyte species, in 106 genera and 39 families, researchers found that both tropical forest and subtropical forest had very high species diversity, which reflects the diversity of microhabitats along the vertical gradient, and the subtropical forest had richer bryoflora than the subtropical forest. 

Besides, they discovered that more species occurred in the canopy than the subcanopy and understorey in both tropical and subtropical forests. The fan life-form was dominant in the lower two layers of both forests, while mats were more common in the canopy of tropical forest and tall turfs in subtropical forest. 

Five red-listed bryophyte species, and 15 new bryophyte records for Yunnan, were also found in this study. 

“Our study demonstrates the value of canopy cranes for complete sampling of the epiphytic bryoflora in complex forests,” said Ms. SHEN Ting, the first author of this study.