The leaf litterfall patterns of Alnus alnobetula subsp. maximowiczii Chery at the timberline of Mt. Fuji, central Japan

Abstract Alnus alnobetula subsp. maximowiczii Chery is a dwarf shrub found at the timberline of Mt. Fuji. This species has been suggested to promote soil eutrophication in two ways: it can fix aerial nitrogen through symbiosis with nitrogen-fixing bacteria in its root system, and its fallen leaves are rich in nitrogen. In this study, we investigated the defoliation and leaf dispersal pattern of A. alnobetula subsp. maximowiczii at the timberline of Mt. Fuji. The petioles of all leaves of A. alnobetula in the research plots were marked with vinyl tape. The marked leaves were collected in November, when all leaves had fallen, and their locations were recorded. We found that leaf litter of this species was scattered above the dwarf shrub community, with the distribution of fallen leaves likely influenced by prevailing winds. The fallen leaves trapped in herbaceous patches above the timberline may contribute to soil eutrophication and accelerate the upward elevational movement of the timberline.