Analysis of Pruning Effecting on Stand Structure and Growth of Pinus yunnanensis

In order to understand effects of pruning on changes of stand structure and growth, the L₄(2³) orthogonal design was applied (two treatments of non- and heavy-pruning as two controls) to implement the experiment of pruning method and intensity for a 10-year-old Pinus yunnanensis plantation which planted as the uneven row spacing schema of the 1 m × 2 m × 5 m in Jianshan Forest Zone, Lufengchun Forest Center, Yiliang County; and stand trees were mensurated before and after been pruned for 2 years. The results showed that diameter grads of the stand were 2-14 and 2-16 cm with the 8, 10 and 10, 12 cm comprised of dominant stand components before and after pruning, respectively. Mean increasing percents of diameters at breast height (DBHs), tree heights, timber volumes for four orthogonal-pruning treatment combination (TC) were 23.4%-28.7%, 28.6%-34.2%, 83.6%-100.3%, while which of the three parameters for non-pruning control were 21.9%, 20.2%, 68.9%, and foe severe-pruning control were 20.3%, 21.4%, 63.4%, respectively; The highest increasing percent of these 3 parameters was found out the TC of handsaw pruning with keeping three wheel branches, and the increasing percents of orthogonal-pruning TCs were higher than which of the non- and severe-pruning TCs. It was significantly improved juvenile stand growth of P.yunnanensis applied proper TCs of pruning method and intensity.