Distribution of species of the Bryum Hedw. genus on the foreland of the Maly Aktru glacier (Severo-Chuisky range, Central Altai Mountains)

Mosses are an impotent component of developing plant communities of glacier forelands of the Russian Altai Mountains. Species of the Bryum genus appear already in the first years after the glaciers retreat and play a significant role at the initial stage of the formation of a closed ground cover.

A study of mosses distribution by successional stages and age fragments on the foreland of the Maly Aktru glacier (Central Altai Mountains) was carried out to assess the species diversity of the Bryum genus.

The Bryum genus is the largest in the floristic list of mosses of the study area and includes seven species (16.3% of the bryoflora, numbering 43 species). It is the species of the Bryum genus among plants that are among the earliest settlers and occur at all three successional stages on the foreland of the Maly Aktru glacier. Four species of Bryum genus, such as B. intermedium, B. caespiticium, B. creberrimum and B. elegans, appear at the pioneer stage of vegetation development, which is characterized by a minimal species diversity of mosses and vascular plants. Six species, such as B. caespiticium, B. capillare, B. creberrimum, B. elegans, B. intermedium and B. lonchocaulon, were found at the second willow-moss successional stage. Six species were identified at the third larch-birch-moss stage of succession, as at the previous stage, but B. pseudotriquetrum appears for the first time and B. lonchocaulon disappears here.

In general, the great diversity of species of the Bryum genus on the foreland of the Maly Aktru glacier is mainly due to the wide distribution of open and rather moist calcium-containing fine earth, which is the optimal substrate for many species of the genus.

The highest frequency of occurrence of species was observed at the second stage (Table). At the same time, a third of the species of the Bryum genus is rare, and another third part is sporadic. Most of the Bryum species noted by us in the studied area grow at all three successional stages. The exceptions are B. lonchocaulon, which is limited in its distribution only to the second stage, as well as B. pseudotriquetrum, which occurs only in the third stage. B. caespiticium is distinguished by the highest frequency of occurrence on the foreland.