Tree Species Drive the Diversity of Epiphytic Bryophytes in the Alpine Forest Ecosystem: A Case Study in Tibet

Epiphytic bryophytes can maintain water, recycle nutrients, and provide habitats for many other organisms in the forest ecosystem. Describing the spatial change of epiphytic bryophytes plays an important role in understanding the potential factors of diversity distribution. The study aimed to determine the influence of environmental factors on their diversity and assemblage in the alpine forest ecosystem of Sygera Mountain. We considered 72 trees, taking into account 1152 quadrats to research the study. Our results showed bryophyte richness first exhibited a hump-shaped pattern and then increased along elevation, reaching a peak at 3500 m. The richness of the eastern aspect was higher than that of the west. Diversity of Quercus semecarpifolia was the highest. There was significant variation among elevations of bryophytes assemblages, especially for the biotopes at 3900 m and 4100 m. The differences among bryophytes assemblages on aspects and tree species were less apparent. Diameter at breast height and elevation influenced assemblage composition. Elevation, tree species, and tree properties drive the diversity of epiphytic bryophytes, and tree species were significantly related to the variation in the diversity of bryophytes. These results are helpful for understanding the relationship between the spatial distribution pattern of bryophytes and the environment.