Vegetation Types Attributed to Deforestation and Secondary Succession Drive the Elevational Changes in Diversity and Distribution of Terrestrial Mosses in a Tropical Mountain Forest in Southern China

(1) Background: Detailed diversity information regarding terrestrial mosses in a tropical forest ecosystem and an understanding of the drivers behind moss distribution provide crucial data for the management and conservation of forest ecosystems. Mosses are critical components of tropical forest ecosystems due to their high diversity and biomass, and they also fulfill essential ecological functions. Here, we report the first study into the relative importance of vegetation types and elevational gradient for the diversity, distribution and community structure of terrestrial moss species in southern China. (2) Methods: Five elevations spaced 200 m apart in the tropical mountain forest on the northern aspect of Tai Mo Shan were selected. The diversity, distribution, and geographical patterns of terrestrial mosses in response to altitudinal changes were examined. Differences in the biotic variables of terrestrial mosses between elevations were tested using a one-way ANOVA. Curve estimation regression models were used to describe the responses of the biotic variables to the elevation gradient. Canonical correlation analysis (CCA) was performed to identify and measure the associations among biotic variables of terrestrial mosses and abiotic environmental factors. (3) Results: Fifty-three terrestrial moss species belonging to 20 families and 31 genera were recorded along the altitudinal gradient on Tai Mo Shan. Microclimate factors including dew point and rainfall were strongly associated with the cover and thickness of the ground moss species. There were no obvious richness changes of terrestrial mosses along the elevation gradient. In total, 33 of the 51 species were tropically distributed, 14 species were found across East Asia and the tropical regions, 10 species had an East Asian pattern and 8 were temperate species. (4) Conclusions: Vegetation types significantly affect the diversity and distribution of terrestrial moss species. Although they are influenced by the East Asian and temperate climate with frequent human activities, terrestrial mosses on Tai Mo Shan are primarily tropical in nature. Forest conservation and restoration should be implemented to sustain and improve the diversity of terrestrial mosses and understory plants on Tai Mo Shan, especially at higher elevations.