PRIMARY PRODUCTION OVER 10 YEARS IN EVERGREEN CONIFEROUS (CHAMAECYPARIS OBTUSA SIEB. ET ZUCC.) PLANTATION IN MT. WATAMUKI-YAMA, SHIGA

Abstract

The primary production in a 48-year-old plantation of C.obtusa reported in the privious papers was studied at Mt.Watamuki-yama in Shiga Prefecture. Eight sample trees were felled and weighed after the stratified clip technique. Allometric relations between D^2H and amounts of various tree parts were used for estimating the biomass and annual increment of the stand per hectare. Branch and leaf biomass in August obtained this time (branch 24.0,leaf 19.2 t ha^<-1> in oven-dry wt.) agreed well those obtained 8 years ago on the same stand. Judging from this and the fact that there was no difference in the number of living trees in the stand during 8 years, it can be said that the biomass increase of above-ground parts was limitted in stem. Mean of annual net production rate among the 10 years from 1967 to 1976 was estimated at 16.5 t ha^<-1>y^<-1> (13.9 t ha^<-1>y^<-1> for aboveground). The range of the net production rates through over 10 years was estimated from 13 to 20 t ha^<-1>y^<-1> in terms of annual changes in stem increment rates and in sum of production rates of stem, leaf and reproductive organs. Net production rate in 1976 was amounted to 15.9 t ha^<-1>y^<-1> (14.3 t ha^<-1>y^<-1> for aboveground).