Dynamic of Forest Density and Growth for Inferior Plantation Thinned of Pinus yunnanensis in the Centre Yunnan

In Lufengcun Forestry Centre of Yiliang County, the Centre of Yunnan, in a 25yearold Pinus yunnanensis plantation which regenerated by seeds directly sowed at a small spot of site preparation, the first thinning was implemented in four 30m×30m sampling plots based 00%, 258%, 315% and 277% thinning intensity on densities of 7311, 4933, 6733 and 4211 tree/hm2 After 10 and 53year of the forest thinned, tally was carried out, and forest densities, tree growth, dead standing trees were calculated The results showed that the thinning effectively facilitated forest growth. Firstly, after 10 and 53year of forest thinned, stands densities of 1-4 sampling plots were declined to 6744、3604、4579、2989 and 3856, 3000, 4278, 2611 tree/hm2, respectively Secondly, after 53year of stand thinned, mean diameters at breast height (DBH) and tree heights for 1-4 sampling plots were increased to 96, 96, 103, 110 cm and 92, 95, 105, 121 m from which of 77, 62, 81, 89 cm and 64, 57, 85, 85 m, respectively, before stands thinned. Thirdly, compared to thinned stands, there was 136% increment of timber volume in the control sampling plot, while which were 1568%, 495% and 375% in 2-4 thinned sampling plots, respectively, in terms of timber volume increments of thinned stands overwhelmingly higher than which of unthinned stand. In 00% thinned forest, there was 550% dead standing trees, while in thinned forests, the valvue was 80%-196%. The results implied that practical thinned intensities could be properly increased in this kind of P. yunnanensis forest.