Key message The use of reduced planting spacings is an important strategy to increase the carbon storage in the above-belowground biomass and should be recommended for future exploitation of forest energy plantations when the purpose intended is the production of biomass for energy. Context Recent concerns about global warming have resulted in more concerted studies on quantifying carbon storage in forest systems. Forest energy plantations play an essential role in the carbon storage. Aims We proposed to evaluate the carbon storage and partitioning in short-rotation forest plantations and to characterize the elemental composition and energetic properties of the forest species Eucalyptus grandis W. Hill ex Maiden, Mimosa scabrella Benth, and Ateleia glazioviana Baill, grown under four planting spacings in Southern Brazil. Methods A field study was conducted in order to evaluate forest carbon stock and wood composition using samples collected by direct method. The four spacings evaluated were 2.0 × 1.0, 2.0 × 1.5, 3.0 × 1.0, and 3.0 × 1.5 m. Results The Eucalyptus grandis stored 327.1 Mg C ha −1 at 2.0 × 1.5-m spacing. When compared with the 3.0 × 1.5-m spacing, we observed a reduction of 29% in carbon stored. All forest species showed higher carbon storage in the following partitioning pattern: trunk>roots>branches>leaves>litter. Forest species energetic properties and elemental composition were not affected by planting spacing. On the other hand, variations according the tree portions were observed. For the carbon stocks in the soil, we observed an average accumulated carbon stock for the forest species studied of 77.4 Mg C ha −1 (0–40 cm). Conclusion Forest managers can accelerate growth and increase the forest carbon storage and biomass yield by using reduced planting spacing that are smaller than the current pattern used by the majority of the forest producers, which is 3.0 × 1.5 m. For Eucalyptus grandis and Mimosa scabrella , the planting spacings recommended to produce biomass and improve carbon stocks were 2.0 × 1.5 and 2.0 × 1.0 m, respectively.

中文翻译：

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减少种植间距下短轮伐林系统的碳储量、分区和木材组成

关键信息 减少种植间距的使用是增加地上地下生物量碳储存的重要策略，应推荐用于未来森林能源种植园的开发，目的是生产生物量作为能源。背景 最近对全球变暖的担忧导致了对量化森林系统碳储存的更一致的研究。森林能源种植园在碳储存中发挥着重要作用。目的 我们建议评估短轮伐期森林人工林的碳储存和分配，并表征在四种种植条件下生长的森林物种 Eucalyptus grandis W. Hill ex Maiden、Mimosa scabrella Benth 和 Ateleia glazioviana Baill 的元素组成和能量特性巴西南部的间距。方法 为了使用直接方法收集的样品评估森林碳储量和木材成分，进行了实地研究。评估的四个间距为 2.0 × 1.0、2.0 × 1.5、3.0 × 1.0 和 3.0 × 1.5 m。结果 大桉树以 2.0 × 1.5 米的间距储存了 327.1 Mg C ha -1。与 3.0 × 1.5 米的间距相比，我们观察到储存的碳减少了 29%。所有森林物种在以下分区模式中均表现出较高的碳储量：树干>根>枝>叶>凋落物。林种能量特性和元素组成不受种植间距的影响。另一方面，观察到根据树部分的变化。对于土壤中的碳库，我们观察到所研究的森林物种的平均累积碳库为 77.4 Mg C ha -1 (0–40 cm)。结论 森林经营者可以通过使用比大多数森林生产者目前使用的模式（3.0 × 1.5 m）更小的种植间距来加速生长并增加森林碳储存和生物量产量。对于巨桉和含羞草，推荐用于生产生物量和改善碳储量的种植间距分别为 2.0 × 1.5 和 2.0 × 1.0 m。