杉木密度间伐试验林林分断面积生长效应

Long-term Effects of Thinning on Stand Basal Area Increment of Cunninghamia lanceolata

通过对26年生杉木密度试验林进行多次间伐后的结果进行比较研究,结果表明:(1)只要人工林立地条件相同,经过足够长的时间,林分断面积最终趋于一致,与是否间伐无关;(2)随间伐次数增加,获得的木材径阶也逐渐增大,未被间伐的保留木则多为大径材;(3)对于立地指数大于16的杉木宜林地,宜采用高密度造林、多次间伐的经营模式,以生产不同规格用材满足木材市场需求,还可提高林分累积断面积的生长量;对于立地指数小于14的杉木宜林地,应该采用稀植造林,以生产小、中径材为主;(4)应在立地条件好、低密度造林条件下培育大径材林木;(5)在立地指数小于14的杉木宜林地,间伐在促进林分断面积生长方面的贡献并不明显,对林分断面积生长起主要作用的因素是立地质量。

Discussed the thinned cumulative stand basal area dynamics after every thinning happened during the past 26 years. The results indicate that （1） As long as site index with the different plots is the same, the cumulative basal area will finally converge to one; （2） The diameter classes increases with thinning processes and the residual individual trees have larger diameter class in common; （3） The plantation with 16 site index should be planted high density and thinned with high frequency so that the different size logs can be obtained and the cumulative stand basal area growth can be promoted. As for 14 site index, we should plant spare plantation so that the small- and mediumsized logs can be produced through spare stand density; （4） The thinning have little effect on the cumulative stand basal area growth with 14 site index; （5） It is possible to obtain the larger diameter classes log which plants high site quality and low stand initial density.