Annual fluctuation during a 15 year period (1993-2007) in the seed rain and seedling dynamics of Betula maximowicziana was investigated at the Ohtakizawa Research Site, Shizukuishi, Iwate Prefecture, to examine the masting habit, relationship between seed rain and seedling emergence, and changes in seedling survival depending on the time having elapsed since a disturbance caused by a typhoon. Significant sound seeds were produced in 1995, followed by medium production in 1998, 2000, 2003 and 2005 and substandard production in other years. The masting habit of B. maximowicziana synchronized with Fagus crenata. The densities of the emerged seedlings correlated with those of the seeds dispersed the preceding year, indicating that the seed rain of the preceding year is the key contributor to emerged seedlings. However, the seedling emergence ratio (relative number of emerged seedlings to the number of dispersed seeds of the preceding year) negatively correlated with the densities of the seeds having dispersed in the preceding year, suggesting that a constant amount of seedlings derived from buried seed bank was emerged regardless the amount of dispersed seeds. The cohorts having emerged earlier following the disturbance caused by a typhoon showed relatively good survival, while the latter cohorts, which emerged more than a decade after the disturbance, disappeared immediately, indicating that there is a limit on the period when seedling emergence and survival is enhanced by a disturbance.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract