Center for Longleaf Pine Ecosystems, School of Forestry and Wildlife Sciences, Auburn University, Auburn, Alabama, 36849, USA.
Southern Research Station, USDA Forest Service, University of Vermont, 81 Carrigan Drive, Aiken Center, Room 208, Burlington, Vermont, 05405, USA.
Ecol Appl. 2017 Jan;27(1):244-259. doi: 10.1002/eap.1439.
Forests can partially offset greenhouse gas emissions and contribute to climate change mitigation, mainly through increases in live biomass. We quantified carbon (C) density in 20 managed longleaf pine (Pinus palustris Mill.) forests ranging in age from 5 to 118 years located across the southeastern United States and estimated above- and belowground C trajectories. Ecosystem C stock (all pools including soil C) and aboveground live tree C increased nonlinearly with stand age and the modeled asymptotic maxima were 168 Mg C/ha and 80 Mg C/ha, respectively. Accumulation of ecosystem C with stand age was driven mainly by increases in aboveground live tree C, which ranged from <1 Mg C/ha to 74 Mg C/ha and comprised <1% to 39% of ecosystem C. Live root C (sum of below-stump C, ground penetrating radar measurement of lateral root C, and live fine root C) increased with stand age and represented 4-22% of ecosystem C. Soil C was related to site index, but not to stand age, and made up 39-92% of ecosystem C. Live understory C, forest floor C, downed dead wood C, and standing dead wood C were small fractions of ecosystem C in these frequently burned stands. Stand age and site index accounted for 76% of the variation in ecosystem C among stands. The mean root-to-shoot ratio calculated as the average across all stands (excluding the grass-stage stand) was 0.54 (standard deviation of 0.19) and higher than reports for other conifers. Long-term accumulation of live tree C, combined with the larger role of belowground accumulation of lateral root C than in other forest types, indicates a role of longleaf pine forests in providing disturbance-resistant C storage that can balance the more rapid C accumulation and C removal associated with more intensively managed forests. Although other managed southern pine systems sequester more C over the short-term, we suggest that longleaf pine forests can play a meaningful role in regional forest C management.
森林可以部分抵消温室气体排放，并有助于减缓气候变化，主要是通过增加生物量。我们量化了美国东南部 20 个管理的长叶松（Pinus palustris Mill.）林的碳（C）密度，这些松林的年龄从 5 年到 118 年不等，并估计了地上和地下 C 的轨迹。生态系统 C 储量（包括土壤 C 的所有库）和地上活树 C 随林龄呈非线性增加，模型预测的渐近最大值分别为 168 Mg C/ha 和 80 Mg C/ha。生态系统 C 随林龄的积累主要是由地上活树 C 的增加驱动的，其范围从 <1 Mg C/ha 到 74 Mg C/ha，占生态系统 C 的 <1%到 39%。活根 C（残桩下 C、地面穿透雷达测量的侧根 C 和活细根 C 的总和）随林龄增加，并占生态系统 C 的 4-22%。土壤 C 与林分地位指数有关，但与林龄无关，占生态系统 C 的 39-92%。在这些经常被火烧的林分中，林下活木 C、枯枝落叶层 C、倒木 C 和枯立木 C 是生态系统 C 的小部分。林龄和地位指数解释了林分之间生态系统 C 变异的 76%。作为所有林分（不包括草本阶段林分）平均值计算的平均根冠比为 0.54（标准差为 0.19），高于其他针叶树的报告。活树 C 的长期积累，加上侧根 C 的地下积累比其他森林类型更大，表明长叶松林在提供抗干扰的 C 储存方面发挥了作用，这可以平衡更密集管理的森林中与更快速的 C 积累和 C 去除相关的作用。尽管其他管理的南方松系统在短期内固存更多的 C，但我们认为长叶松林可以在区域森林 C 管理中发挥重要作用。
