Planting Density Effects on the Growth, Stem-form Quality and Stand Differentiation of Manglietia yuyuanensis Plantation

The effects of planting density on the growth, stem-form quality and stand differentiation of Manglietia yuyuanensis plantation were analyzed by using 10 years old data from the experiment stand (including treatments of 2 500, 3 000, 3 600, 4 500 trees/hm² respectively), and then the comprehensive evaluation of the different planting densities were evaluated by the multi-objective decision-making method. The results showed that it had significant planting density effects on 5 growth indices including height, DBH, crown width, individual volume and stand volume, 5 stem-form quality indices including stem straightness, stem fullness, crown length ratio, diameter height ratio, branch height, and 2 stand differentiation indices including the number ratio of below grade II and III wood. With the increase of planting density, average DBH, crown width, crown length ratio, and single volume of M. yuyuanensis decreased; with the increase of planting density, tree height, stem straightness, stem fullness, ratio of height to diameter, branch height and the number ratio of below grade II and III forest wood of M. yuyuanensis increased; with the increase of planting density, stand volume of M. yuyuanensis increased first and then decreased. The planting density had no significant effect on survival rate, breast height factor of M. yuyuanensis. It had significant planting density effect on the comprehensive performance of M. yuyuanensis, it showed that is necessity to reasonable planting density, through analysised and gave the conclusion that 2 500−3 600 trees/hm² was the reasonable plantation densities for the cultivation of large diameter timber of M. yuyuanensi.