Abstract:
In Lufengcun Forestry Centre of Yiliang County, the Centre of Yunnan, in a 25yearold 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 00%, 258%, 315% and 277% thinning intensity on densities of 7311, 4933, 6733 and 4211 tree/hm2 After 10 and 53year 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 10 and 53year 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 53year of stand thinned, mean diameters at breast height (DBH) and tree heights for 1-4 sampling plots were increased to 96, 96, 103, 110 cm and 92, 95, 105, 121 m from which of 77, 62, 81, 89 cm and 64, 57, 85, 85 m, respectively, before stands thinned. Thirdly, compared to thinned stands, there was 136% increment of timber volume in the control sampling plot, while which were 1568%, 495% and 375% in 2-4 thinned sampling plots, respectively, in terms of timber volume increments of thinned stands overwhelmingly higher than which of unthinned stand. In 00% thinned forest, there was 550% dead standing trees, while in thinned forests, the valvue was 80%-196%. The results implied that practical thinned intensities could be properly increased in this kind of P. yunnanensis forest.