Bryophyte societies on the fallen logs of Pinus armandii with different decay classes in Sygera Mountains

Aims Fallen logs play important roles in maintaining the health and the renewal of forest ecosystems, but the difference of bryophyte societies on fallen logs with different decay classes is unclear.
Methods To understand the regularity and influencing factors of changes in bryophyte societies, we investigated the bryophytes with quadrats along the trunks on four fallen logs of Pinus armandii with different decay classes at the same site in Sygera Mountains, Xizang. Then, the measured data were collected and analyzed.
Important findings There were 22 families and 52 species of bryophytes inhabiting the four fallen logs, including 13 families and 38 species of Musci, 9 families and 14 species of Hepaticae. According to the characteristics of the shared dominant species, 14 societies were obtained. With the increase of decay classes of fallen logs and changes in surrounding environment, the bryophyte diversity increased gradually, while the number of societies and the total bryophyte coverage fluctuated. Bryophyte species varied from drought-tolerant tall turfs, such as Orthotrichaceae and Leucobryaceae, to fast-growing cushions or mats in humid and shady environments, such as Mniaceae, Thuidiaceae and Brachytheciaceae. The complexity of spatial structure of bryophytic society increased gradually. Fallen logs are important growth substrates for a variety of bryophytes. Bryophyte societies on fallen logs vary with decay classes, moisture and light conditions.