Author(s)

O. Hanada, Y. Yamada & M. Takezawa

Abstract

Type of trees vary over different localities in Japan but the Japanese cedar and the Japanese cypress cover a wide area. The Japanese cedar and the Japanese cypress were specifically planted from the 1950s. The Japanese cedar and the Japanese cypress have been growing thickly in recent times as a result of not thinning out the forest. A relevant factor in this lack of forest tending is the large quantity of cheap lumber imported from some foreign countries. As a result, a large quantity of pollen is scattered over the country and many cases of allergy to cedar pollen are reported. The rate of allergy to cedar pollen is gradually increasing every year and the number of people suffering is about 10,000,000 in Japan at present. Bronchial asthma has also taken a turn for the worse due to allergy to cedar pollen. The Japanese cedar and the Japanese cypress will also seek less crowded areas or will produce a greater quantity of seeds when blossoming, which will contribute to pollen allergies. Potential countermeasures are as follows: (1) Adequate thinning out of forests; (2) a change in the type of tree planted from the cedar and cypress to other trees to reduce the amount of airborne pollen; and (3) an increase in the number of trees with fruits or nuts. Keywords: forest, forestry, Japanese cedar, Japanese cypress, allergy, fruit, nut. 1 Introduction Recently, cases of allergy to cedar pollen and damage caused to farms by wild animals is increasing because of a lack of forest tending in Japan. It is generally accepted that cedar pollen and exhaust gases contribute to allergies in Japan.

Keywords

forest, forestry, Japanese cedar, Japanese cypress, allergy, fruit, nut.