[Pollen dispersion of Cryptomeria japonica in autumn]

To clarify the significance of pollen dispersion of Cryptomeria japonica in autumn, the distribution pattern of pollen dispersion using specimens collected from 1987 to 1995 by Durhum collector was examined. After the dispersion period in the spring, the pollen count was suddenly decreased. The total pollen count from October to December showed no relation to the total pollen count for that of in spring of the same year; but it was closely correlated (r = 0.877) with the total pollen count during the dispersion period in the spring of the next year. In particular, accurate correlation between the total pollen count during November and that in January to May of the following year was observed with the correlation index of r = 0.909. Patients with a pollinosis probably for Cryptomeria japonica were also observed in the autumn. These results suggest that we can forecast the degree of pollen dispersion of Cryptomeria japonica in the coming year from the total pollen count during November of the year before.