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.

Rare and endangered plant species (REPs) are important in biodiversity conservation, and some REPs with narrow habitats are facing serious challenges from climate change. Encalypta buxbaumioidea T. Cao, C, Gao & X, L. Bai is an endangered bryophyte species that is endemic to China. To explore the consequences of climate change on the geographic distribution of this endangered species, we used maximum entropy to predict the potential distribution of this species in China under current and three future scenarios (RCP 2.6, RCP 4.5, and RCP 8.5) of two time periods (2050 and 2070) in China and assessed its conservation gaps. Twelve species occurrence sites and nine environmental variables were used in the modeling process. The results show that E. buxbaumioidea distribution is affected mainly by the annual mean temperature, isothermality, precipitation of the coldest quarter, and NDVI. According to species response curves, this species preferred habitats with annual mean temperature from −3 to 6 °C, precipitation of the coldest quarter from 14 to 77 mm, isothermality of more than 70%, and NDVI in the second quarter from 0.15 to 0.68. Currently, the most suitable habitat for this species is mainly distributed in the Qinghai–Tibet plateau, which is about 1.97 × 105 km2. The range would sharply reduce to 0.13–0.56% under future climate change. Nature reserves overlap with only 7.32% of the current distribution and would cover a much less portion of the area occupied by the species in the future scenarios, which means the current protected areas network is insufficient. Our results show that endangered bryophyte species are susceptible to environmental stress, especially climate change; therefore, the habitats of bryophytes should be taken into account when it comes to setting up protected areas.