Journal of the Japanese Society of Snow and Ice

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Snow avalanche disturbances are important processes in subalpine forest ecosystems, but current knowledge of the interaction between avalanches and vegetation dynamics is largely lacking. This paper elucidates the role of avalanche disturbances in subalpine ecosystems on the northern slope of Mt. Fuji. Using ecological indicators and tree-ring analysis, we analyzed avalanche chronologies and vegetation patterns on avalanche tracks. We identified 19 snow avalanche tracks and divided them into two types based on topographic characteristics. The first type of track is formed by lava flows, occurs on steep stream gradients, and experiences frequent avalanches with 1.6-6-year return intervals. The second type is formed by volcanically erupted scoria, occurs on less steep inclines, and experiences infrequent avalanches with return intervals of greater than either 150 years or 300 years, depending on conditions.We found that return intervals and level of disturbance severity can provide insights into vegetation dynamics. Frequent snow avalanches maintain persistent characteristic communities̶such as pioneer herbaceous communities (Fallopia japonica and Aconogonon weyrichii), disclimax communities (deciduous broadleaved bushes, especially Alnus Maximowiczii), and edaphic climax communities (Betula ermanii forest)-in ecological succession. However, infrequent avalanches destroy climax forests, and forest development after avalanches follows one of three different pathways̶new recruitment of Larix kaempferi or of B. ermanii, or reorganization of surviving Abies veitchii seedlings̶according to event severity. These findingssuggest that snow avalanche disturbances create plant communities in various stages of succession and contribute to increased diversity of subalpine forest ecosystems on the northern slope of Mt. Fuji.

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