Effects of pruning on growth dynamic and veneer quality of Eucalyptus urophylla×E. grandis

Using Eucalyptus urophylla×E. grandis plantation as the research material in this paper, the effects of pruning on the growth dynamic and veneer quality were studied by setting four pruning intensities of CK (no pruning), light pruning (cut 25% of the whole canopy), moderate pruning (cut 33.3% of the whole canopy) and heavy pruning (cut 50% of the whole canopy), and pruning in consecutive 2 years with applying split-plot experiment design. The results showed that the growth of young E. urophylla×E. grandis was most influenced by pruning intensity, especially with the increasing of trees age. The increase of diameter at breast height (DBH) was affected under the principle of nearby allocation of biomass; however the growing on the height of tree was affected quite less than that for DBH. The reason of this phenomenon was mainly related to the height of canopy and net photosynthetic rate after pruning. The tree volumes for both bi-monthly continuous and regular growth in 2013 were nearly the same under four pruning intensities after two consecutive pruning in 2011 and 2012. The veneer quality was improved by the heavy pruning, which was able to increase green knots and decrease dead knots per unit area. The heavy pruning is most appropriate method for directive breeding of clear wood based on the growth and veneer quality of E. urophylla×E. grandis.