2018 Volume 100 Issue 4 Pages 102-109
Roles of bryophyte communities in germination and early growth of tree species were studied in a subalpine forest dominated by deciduous broad-leaved tree species in central Japan where logging was conducted approximately 60 years ago. Tree to subtree layers of the investigated stand were dominated by Betula ermanii and these trees produced many seeds. However, Abies veitchii and Abiesmariesii occupied the space under tree layers, implying that the B. ermanii-dominated forest was in a transition toward an evergreen coniferous forest dominated by Abies species. Analysis of undergrowth on the ground and fallen logs indicated that plant communities were classified into four types, namely, Cacalia adenostyloides type and Oxalis acetosella type on the ground, and Scapania bolanderi type and Pleurozium schreberi type on fallen logs. Many seedlings and saplings occurred in bryophyte communities of two types on fallen logs, and Abies species had the highest density in P. schreberi type. Height and age of Abies seedlings and saplings were higher in communities of P. schreberi type than in S. bolanderi type. We conducted field experiments on seed-retention effects of two bryophyte cover types (S. bolanderi and P. schreberi) and no cover on logs and on the survival rate of current-year A. veitchii seedlings until autumn in the four undergrowth types. These results suggest that bryophyte communities on a log can function not only as a seed trap but also as a seedling bed, and therefore, they have a driving role in forest succession.
