綿向山山麓にあるヒノキ林のリターフォールの季節変化

抄録

Litterfallrates in Chamaecyparis forest planted in 1929 on a gentle slope of Mt. Watamuki-yama was measured from 1966 to 1976. The peak of leaffall was found in autumn, but the fall of fresh and green leaves occurred irregularly in all seasons associated with storms or heavy snowfall. The death of older leaves occurred in October once a year, but the leaffall continued until the following early spring. The yellow coloring of leaves in autumn began after the daily minimum temperature had dropped under 7℃ and finished at -9 to -10℃・d of the accumulative temperature expressing the degree of coldness during the final period of growing season. It is possible to measure the death rate of leaf, the production rates of cone, seed and male flower, and the fall rates of green leaf, branch and bark, with catching the fall by litter traps. The standard deviations of the fall rates decreased with increase in the mean fall rate for all organs except for cone, For the cone it increased in proportion to the mean fall rate for the year of high production.