Effect of Stem Pruning on Growth and Knot Free Timber Production of Fokienia hodginsii Plantation

The pruning of 6 year-old Fokienia hodginsii plantation in Nanjing State-owned Forest Farm of Fujian were studied.The results showed that:Stem pruning accelerated the growth and biomass accumulation of Fokienia hodginsii plantation.4 years after stem pruning,the height,DBH,biomass and stem volume of single tree,growth rate of stem volume and stem volume accumulation increased by 10.5%～20.9%,2.6%～8.1%,14.9%～37.2%, 18.2%～44.3%, 18.74%～39.44% and 6.84～16.68 (m3·hm-2) respectively.The pruning intensity of 50% in all treatment had the best accelerating effect. Stem pruning reduced the acuminate intensity and increased the chubbiness intensity, the value of H/D increased by 7.0%～14.1% compared with CK;The pruning start age of 6 year-old was most effective in reducing acuminate intensity,increasing growth rate of stem volume and accelerating concrescence,the secondly effective treatment was 5 year-old,the worst was 11 year-old.In the condition of 6 year-old pruning start age and 50% pruning intensity,the holding density of 1 200 plant.hm-2 was most effective in increasing height,DBH, biomass and stem volume of single tree,and growth rate of stem volume. The pruning intensity and alternation time can be decided by relative growth curve of side branch.