裏日本系スギ林の生殖器官生産量および花粉と種子生産の関係

抄録

Annual production rates(by dry weight/number)of pollen, male flowers, seeds and cones in three natural stands, A, B and C(100-200 years old), and an artificial stand D(50 years old)of Sugi(Cryptomeria japonica D. DON)of Japan Sea Type were measured by litter traps and analyzed. Production rates of pollen dispersed into the air were estimated from enumeration of fall rates of open male flowers per hectare and dry weight/number of pollen grains per flower sample before anther opening. Pollen production rates in 1981-1986 were in the range of 3.4-430kg/ha・yr and 0.43×10¹²-49×10¹² no./ha・yr, and the mean values of four stands over the seven years' period were 63kg/ha・yr and 6.6×10¹² no./ha・yr, which were nearly equal to those described in Japanese red pine and Siebold walnut stands. In accordance with the numerical ratio of pollen to seed production, two types of dry matter production over reproductive organ are distinguished ; one being a high proportion(60-70%)of male parts to the total dry matter production, and the other, a low proportion (40-50%). Of the numerical ratios of pollen grains to seeds and male flowers to seeds, the former is about four times higher than the latter, which had no relation to mast and lean years. Stands A, B and D were classified into the former type, and C into the latter.