Harris Lucas B, Woodall Christopher W, D'Amato Anthony W
Rubenstein School of Environment and Natural Resources University of Vermont Burlington Vermont USA.
USDA Forest Service, Research and Development Inventory Monitoring and Assessment Research Durham New Hampshire USA.
Ecol Evol. 2024 Aug 7;14(8):e70077. doi: 10.1002/ece3.70077. eCollection 2024 Aug.
Tree regeneration shapes forest carbon dynamics by determining long-term forest composition and structure, which suggests that threats to natural regeneration may diminish the capacity of forests to replace live tree carbon transferred to the atmosphere or other pools through tree mortality. Yet, the potential implications of tree regeneration patterns for future carbon dynamics have been sparsely studied. We used forest inventory plots to investigate whether the composition of existing tree regeneration is consistent with aboveground carbon stock loss, replacement, or gain for forests across the northeastern and midwestern USA, leveraging a recently developed method to predict the likelihood of sapling recruitment from seedling abundance tallied within six seedling height classes. A comparison of carbon stock predictions from tree and seedling composition suggested that 29% of plots were poised to lose carbon based on seedling composition, 55% were poised for replacement of carbon stocks (<5 Mg ha difference) and 16% were poised to gain carbon. Forests predicted to lose carbon tended to be on steeper slopes, at lower latitudes, and in rolling upland environments. Although plots predicted to gain and lose carbon had similar stand ages, carbon loss plots had greater current carbon stocks. Our results demonstrate the utility of considering tree regeneration through the lens of carbon replacement to develop effective management strategies to secure long-term carbon storage and resilience in the context of global change. Forests poised to lose C due to climate change and other stressors could be prioritized for regeneration strategies that enhance long-term carbon resilience and stewardship.
树木更新通过决定森林的长期组成和结构来塑造森林碳动态，这表明对自然更新的威胁可能会削弱森林替换因树木死亡而转移到大气或其他库中的活树碳的能力。然而，树木更新模式对未来碳动态的潜在影响却鲜有研究。我们利用森林清查样地来调查美国东北部和中西部森林中现有树木更新的组成是否与地上碳储量的损失、替换或增加相一致，采用了一种最近开发的方法，根据在六个幼苗高度等级中统计的幼苗数量来预测幼树补充的可能性。根据树木和幼苗组成对碳储量预测进行的比较表明，基于幼苗组成，29%的样地碳储量将减少，55%的样地碳储量将得到替换（差异<5 Mg/公顷），16%的样地碳储量将增加。预计碳储量减少的森林往往位于更陡峭的山坡、较低的纬度以及起伏的高地环境中。尽管预计碳储量增加和减少的样地林龄相似，但碳储量减少的样地当前碳储量更高。我们的结果表明，从碳替换的角度考虑树木更新对于制定有效的管理策略以确保在全球变化背景下的长期碳储存和恢复力具有实用价值。由于气候变化和其他压力因素而可能失去碳的森林，可以优先考虑采用增强长期碳恢复力和管理的更新策略。
