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在 6～ 18年生湿地松、火炬松用材林中布置了 10片间伐强度试验林 ,对不同间伐处理的林分测树因子和间伐作业经济效益进行了分析 ,最后确定了两个树种工业用材林密度调控方案。正常情况下 ,2 0 0 0株· hm-2以下密度林分 8年生后间伐即有收益 ,而首次间伐龄应在 12年生之前方能使保留木生长速率获得提高。通过间伐可使立木规格材出材率略有提高 ,但伐后 4～ 6 a间 ,立木蓄积量、规格材出材量、林分总收获量基本上随间伐强度加大而减少 ,两次间伐的间隔期至少应在6 a以上。综合考虑立地条件、生长效应和经营目的 ,认为两个树种工业用材林营建应选择立地指数14～ 18林地 ,培育纸浆材林分 ,初植密度 2 0 0 0～ 16 6 7株· hm-2 ,或 15年生主伐 ,或 8～ 10年生作中强度间伐至 12 0 0株· hm-2左右 ,18～ 2 0年生主伐 ;培育建筑材 ,初植密度 16 6 7～ 1111株·hm-2 ,10～ 12年生第 1次间伐至 110 0～ 80 0株· hm-2 ,16～ 18年生第 2次间伐至 80 0～ 50 0株·hm-2 ,2 0～ 2 5年生时主伐
In the 6 to 18 year wetland pine, loblolly pine timber plantation layout of 10 thinning strength test forest, different thinning treatment of the tree measuring tree factor and thinning operation economic benefits were analyzed, and finally determine the two species of industrial timber density control Program. Under normal circumstances, the planting density of 2000 logs · hm-2 or below can benefit from thinning after 8 years, and the growth rate of reserved wood can be increased before the initial cutting of 12 years. Through thinning, the timber yield of timber can be slightly increased. However, between 4 and 6 months after cutting, the storage volume of timber, the amount of timber of timber for specification and the total amount of forest stand basically decreased with the increase of thinning strength. Thinning interval should be at least 6 a. Considering site conditions, growth effects and business purposes, it is considered that the establishment of industrial timber forests for the two tree species should select site indices of 14 to 18 forestlands, cultivating pulpwood stands with initial planting density of 2000 to 1667 plants · hm-2, Or 15-year-old cutting, or 8-10-year-old medium-density thinning to about 12 0 · hm-2, 18 to 20 years of primary cutting; cultivate building materials, initial planting density of 16 6 7 ~ 1111 plants · hm- 10 ~ 12-year-old first thinning to 110 0 ~ 80 0 plant · hm-2, 16 to 18 year-old second thinning to 80 0 ~ 50 0 plant · hm-2, 20 to 25 years old when the main cutting