Effect of bryophytes on survival of conifer seedlings in subalpine forests of central Japan

Bryophytes form the major seedbed for coniferous trees in the subalpine forests of central Japan. Field experiments were conducted on the floor of a closed stand dominated by Tsuga on Mt Fuji to examine the seedling survival of Abies veitchii and Tsuga diversifolia in seven substrate types in relation to the morphological characteristics of the seeds and seedlings. Neither Abies nor Tsuga seedlings could survive on dwarf‐bamboo litter beyond 2 years after the seed rain. Abies seedlings survived not only in all types of bryophyte communities but also in larch litter. In contrast, the survival of Tsuga seedlings was restricted to communities of smaller‐statured bryophytes found on logs. The seeds and 1st year seedlings of A. veitchii were larger than those of T. diversifolia. Abies seedlings produced hypocotyls taller than any bryophyte community and radicles which were long enough to penetrate into the moist humus layer, whereas Tsuga seedling radicles presumably penetrate into humus only in bryophyte communities forming a thin mat on logs. The effect of bryophytes on survival of tree seedlings therefore depends on the relationships between the morphology of seeds and seedlings and the structure of bryophyte communities.