Pollen dispersion of Japanese ceder and cypress trees in Hiroshima prefecture

Abstract

We have been conducting an on-going survey of pollen dispersion from Japanese ceder and cypress trees (cryptomeria japonica and cypressaceae) since 1988 at the Hiroshima Mitsubishi Hospital in Horoshima city. We examined the correlation between the annual variations in the pollen counts of cedar and cypress trees and the annual changes in meteorological conditions. The sum of these pollen counts correlated with the sunshine duration in June and July of the previous year. In addition, the beginning of the pollination season correlated with the mean temperature from January 1st to January 20th. However, it is difficult to determine the pollen dispersion only based on meteorological factors.
Furthermore, we have also been conducted a survey on pollen dispersion over the past 6 years at 9 locations in Hiroshima prefecture. Hiroshima City, Hatsukaiti city (western Hiroshima prefecture), Kabe Town and Miyoshi city (northern Hiroshima prefecture), Onomichi city, Innoshima Island and Fukuyama city (eastern Hiroshima prefecture) and Kure city.
In Hiroshima prefecture, the dispersion patterns were simillar to those for Hiroshima city, Kure city and western Hiroshima prefecture, however the total pollen count was higher than that for northern Hiroshima prefecture. In addition, in eastern Hiroshima prefecture, it was only about half or a third as much as that for Hiroshima city. The results thus suggest that these three areas in Hiroshima prefecture need to be further analyzed in the future.