Beech species (Fagus sp.) shows long interval reproduction known as masting event. Although (carbon) resource limitation is a candidate for the cause of long interval masting, there are some evidences that current photosynthates are primal carbon source for fruit maturation in beech species. On the other hand, considerable amount of carbon resources is also needed for maintenance and growth of non-photosynthesis parts during reproduction. Therefore, the existence of carbon sources other than current photosynthesis should play an important role in whole plant level during the reproductive period. In this study, we aimed to evaluate the effect of reserved carbon resource levels in individual scale on the reproduction in Japanese beech (Fagus crenata). To this end, we monitored a reproductive event of the beech in Mt. Naeba, central Japan. And 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.
Results/Conclusions
In the spring of the seeding year, all of the observed trees (n=20) flowered and the amount of flowers varied among trees. There was no relationship between root NSC concentration at any periods 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 decreased in the masting trees after reproduction but root NSC in the few seeding ones increased. These results suggested that the amount of carbohydrate at individual level was not direct key signal of reproduction event in Japanese 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.