STUDIES ON PRODUCTIVITY OF PINUS TABULAEFORMIS STANDS IN TAI YUE MOUNTAIN, SHANXI PROVINCE
Forest Ecology Research Group,Forestry College of Beijing Tai Yue Mountain Forest Bureau
Biomass production of pinus tabulaeformis plantations in Tai Yue MountainShanxi province was determined.Data of 8 sample plots from stands of differentdensities were collected for analysis.Current biomass production of parts aboveground was 57. 5T/ha in average,and that of 24-year plantation was 79. 6T/ha.Mean annual growth was 7.8T/ha,net assimilation 0.885T/ha/yr, and relativerate of growth was 16.8%. Productivity of the plantation is considered to beof middle level. As shown by regression,relative growth rate of stands is closely correlatedwith density of the plantation. A maximal value was found in stands withdensity of 6000 stems/ha,while that of stand with density 20,000 stems/hawas in minimum.Relation of relative growth rate to leaf area ratio and netassimilation rate can be expressed by following equations. RGR = 3. 5028NAR-0. 1488 r= 0. 997 RGR = 0. 1859LAR-D. 1746 r= 0. 989 Over density is a factor holding back the current growth of the plantation.Form growth analysis indicated that plantation should be thinned at 13-15years of age.