Ecological and Physiological Studies on the Vegetation of Mt. Shimagare VI

Growth and dry matter production, and consumption of dry matter by respiration and shedding of a young Abies stand about 15 years old were estimated in the subalpine zone (at altitude of 2, 340m) of Mt. Shimagare, Nagano Prefecture, Central Honshu. Seasonal changes of biomass of new organs were pursued by samplings at intervals of one or two months during the growing season of 1960. The dry weight of new leaves increased till the end of August, while that of new branches increased till the end of October. The total biomass of the stand at the end of the growing season was 3.3kg d. w./m2. Leaf biomass of 1.0kg d. w./m2 of this young stand was about a half of that in the mature subalpine Abies stand of the adjacent region.Net production of the young stand, 0.74kg/m2•yr, was about 65% of that of the mature. Both stands were nearly equal in production of leaves and branches, so the difference in the net production was mainly attributed to that in the production of stems and roots. About 70% of the net production of the young stand contributed to the increase of biomass, and the rest was lost by shedding of leaves.Annual respiratory loss was estimated at 1.25kg/m2 by the measurements of seasonal change in respiratory activity of each organ. This amount was about 63% of the gross production, which was estimated to be 1.99kg/m2•yr as the sum total of the net production and the respiration.