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山杨系我省天然次生林的主要树种之一。本文对东峡地区39年生山杨天然次生林生物量进行了测定。结果表明,林分生物量为80.75t/ha。其中乔木层生物量65.46t/ha,占总量的81.07%,乔木层生物量在各器官的分配规律是:干材>根系>树叶>枝条>树皮。树龄30年左右时,乔木层总净生产量及干材净生产量均处于速生阶段,此后,逐年下降,但到39年时,仍比该期第一性净生产力大。因此,确定山杨皆伐年龄应在39年以上。
Mountain Yang Department of natural secondary forest in our province one of the main species. In this paper, the biomass of the natural secondary forest of 39-year-old Populus euphratica in Dongxia was measured. The results showed that stand biomass was 80.75 t / ha. Among them, the biomass of arbor layer was 65.46t / ha, accounting for 81.07% of the total. The distribution rule of arbor layer biomass in different organs was as follows: stem> root> leaf> branch> bark. When the tree age was about 30 years old, the total net production of tree layer and the net production of dry biomass were both at the fast-growing stage, and then decreased year by year. However, by 39 years, the net primary production was still larger than that of the first generation. Therefore, the definition of aspen clear-cut age should be 39 years.