Effects of snow pressure on growth form and life history of tree species in Japanese beech forest

. In the cool temperate zone in Japan Fagus crenata (beech) is a highly dominating climax species, especially in the snow‐rich regions at higher altitudes. The explanation for this dominance was studied with special reference to the tolerance of tree trunks to snow pressure. Traits of six tree species: trunk bend, trunk height decrease, trunk damage and basal sprouting rate were measured in Fagus forest in the Echigo Mountains, central Japan along a snow pressure gradient. The following general trends were recognized: (1) trunk bend and trunk height decrease; (2) snow pressure caused trunk injury; (3) when the trunk bend exceeded a critical angle, the number of sprouts increased remarkably. Although the tolerances were different among the six species, most of them were seriously damaged by snow pressure, and many trunks were reduced in size. On the other hand, many sprouts emerged from deformed trunks and contributed to the maintenance of the population under heavy snow pressure. F. crenata was the only species whose trunk form and maximum size were hardly influenced by snow pressure.