Thinning Trial and Its Benefit Analysis of Populus בBeijingensis’

This paper deals with the thinning trial for plantation of PopulusבBeijingensis' from 1981 to 1989. The planting spacing of the plantation was 2m×4m. The cutting was conducted beginning from the spring of 1985, and the cutting intensity was 63.0%, 47.4% and 42.0% respectively. The results showed that there was great difference in tree growth, structure and economic benefit in stands with different cutting intensity; The cutting intensity had a great influence on the diameter grade of the trees, year of maturity and stem form. The values of breast height diameter, volume growth and increment volume of the 9-year-old plantation of the check stand were 17.0cm, 0.1832m3 and 229.00 m3/ha in average respectively, while those for the stands with thinnings of 42.0%, 47.3% and 63.0% of the trees were 19.8cm, 0.2402m3, 172.94m3/ha, 21.0 cm,0.2683m3, 176.54 m3/ha and 22.4 cm, 0.3017m3, 139.39 m3/ha in average respectively; The timber yield of the check stand was the highest, though its price was low, its total production value was still the biggest: 52670.00 yuan/ha for 9-year-old plantation, 5 852.22 yuan/ha per year in average. While those for the stand with a thinning of 63% of the trees were the lowest: 38 210.75 yuan/ha and 4 245.64 yuan/ha respectively. Stands with thinning of 47.3% and 42.0% of the trees got better results among the different cutting intensities. On the whole, thinning utilization was not worth-while in the respect of timber yield and economic benefit. Spacing 2m×4m is suitable only for culturing middle-diameter timber, while 7 year clear felling is the best.