不同密度南方型杨树人工林的主伐年龄研究

根据湖北省10个县、市31块标准地的11种主要密度类型林分的调查资料,从技术经济学的角度,以林分数量成熟与经济成熟为依据,对各密度类型林分的主伐年龄进行了研究,结果表明:①南方型杨树各种密度类型人工林的年均收益最大值出现在材积连年生长量最大值与数量成熟龄之间,一般早于数量成熟龄1～2a。②林分的主伐年龄与数量成熟龄表现出随着林分密度的减少而逐渐变大的总趋势,而主伐年龄时的最大年均净收益则随林分密度增大而增加,与林分单位面积蓄积量的变化趋势基本一致。③培育造纸、刨花板等小径材林分的轮伐期为5～6a,木芯板、火柴、家具等中径材的轮伐期为6～9a,培育胶合板等大径材的年限则需要10～12a。

Study on Ages of Final Cutting on Plantation for Southern Type of Poplar under Different Densities

On the basis of investigation data from 31 standard plots with 11 main density types at 10 counties and cities in Hubei province, ages for final felling on stands with various densities south poplar were studied from the angle of tech—economy and based on quantitative maturity and economic maturity in this paper. The results indicated that: ① Maximum value for annual mean benefit from all kinds of poplar plantation is occurred between quantitative maturity age and time when maximum value is occurred increment annual volume increment i.e. generally 1～2 years earlier than the quantitative maturity years. ② With decrement in stands density, stand age for final cutting will show a general (?)end toward progressive enlargement together with quantitative maturity age stands, but, the maximum annual mean net benefit during final cutting will increase along with increment in stand density i.e. basically identical with changing trend in stand stock per area. ③ The rotation is 5～6 years for cultivation of stand for small diameter timber used for paper—making and particle board, but 6～9 years for middle diameter of timber used for core board, match and furniture and 10～12 years for large diameter of timber used for plywood.