Beech (Fagus crenata) shows long interval reproduction known as masting event, and resource limitation is a candidate for the cause of masting. To evaluate the effect of carbon resource levels in individual scale on the reproduction in beech, the concentrations of root non-structural carbohydrate (NSC, an indicator of individual level of carbon status) were compared between masting trees and no/few reproductive ones at the three periods; pre-seeding summer (at the flower formation), pre-seeding winter and post-seeding winter.

In the spring of the seeding year, all of observed trees flowered and the amount of flowers varied among trees. There was no relationship between root NSC concentration and the amount of flowers. On the other hand, masting trees had higher root NSC concentrations than few seeding ones at the pre-seeding winter. The root NSC concentration in masting trees decreased after reproduction but root NSC in few seeding ones increased. These results suggested that the amount of carbohydrate at individual level was not direct key signal of reproduction event in beech but they constrained seeding success, and that carbohydrate reserve was used for growth and maintenance of root and stem during the reproductive period in masting trees because current income was consumed for reproduction.