Analysis of Production Processes of an Undergrowth of Subalpine Abies Forest, Pteridophyllum racemosum Population

1 Growth, Carbohydrate Economy and Net Production

抄録

Annual growth cycle and seasonal changes of carbohydrate reserves in various organs were studied with populations of Pteridophyllum racemosum, an evergreen perennial herb of Papaveraceae, grown as an undergrowth of the subalpine Abies forest (2, 250m in altitude) of northern Yatsugatake Mountains, central Japan. The plants unfolded late in May, soon after snow melting. The growth of new organs in dry weight was inclined to leaves and flower stalks in early growing season and to roots in late summer and autumn. The annual growth of new organs of the population reached 51.5g d. w./m².
Seasonal changes of sugar, starch and hemicellulose contents in leaves, roots and rhizomes were pursued. Carbohydrate reserves in the old organs decreased in the early growing season till the end of June, corresponding to the period of rapid development of new leaves and flower stalks. The old leaves as well as roots and rhizomes exported considerable amount of reserves in this period showing that they played in winter a role as the reserve organ. Reserves were filled again in overwintering old organs till the end of the growing season.
By combining monthly dry weight increments in new organs and the consumption or accumulation of reserves in old organs, monthly and annual net production of the population were calculated. The latter was 40.5g/m²•yr which corresponded to 3.6% of the annual net production of the canopy Abies trees. During the initial two and a half months of the growing season, till the end of July, the plant produced 72% of the annual net production.