The United States Great Lakes Region (USGLR) is a critical geographic area for future bioenergy production. Switchgrass (Panicum virgatum) is widely considered a carbon (C)‐neutral or C‐negative bioenergy production system, but projected increases in air temperature and precipitation due to climate change might substantially alter soil organic C (SOC) dynamics and storage in soils. This study examined long‐term SOC changes in switchgrass grown on marginal land in the USGLR under current and projected climate, predicted using a process‐based model (Systems Approach to Land‐Use Sustainability) extensively calibrated with a wealth of plant and soil measurements at nine experimental sites. Simulations indicate that these soils are likely a net C sink under switchgrass (average gain 0.87 Mg C ha⁻¹ year⁻¹), although substantial variation in the rate of SOC accumulation was predicted (range: 0.2–1.3 Mg C ha⁻¹ year⁻¹). Principal component analysis revealed that the predicted intersite variability in SOC sequestration was related in part to differences in climatic characteristics, and to a lesser extent, to heterogeneous soils. Although climate change impacts on switchgrass plant growth were predicted to be small (4%–6% decrease on average), the increased soil respiration was predicted to partially negate SOC accumulations down to 70% below historical rates in the most extreme scenarios. Increasing N fertilizer rate and decreasing harvest intensity both had modest SOC sequestration benefits under projected climate, whereas introducing genotypes better adapted to the longer growing seasons was a much more effective strategy. Best‐performing adaptation scenarios were able to offset >60% of the climate change impacts, leading to SOC sequestration 0.7 Mg C ha⁻¹ year⁻¹ under projected climate. On average, this was 0.3 Mg C ha⁻¹ year⁻¹ more C sequestered than the no adaptation baseline. These findings provide crucial knowledge needed to guide policy and operational management for maximizing SOC sequestration of future bioenergy production on marginal lands in the USGLR.

中文翻译：

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预测气候变化和适应策略下边缘土地上柳枝switch的土壤碳变化

美国大湖区（USGLR）是未来生物能源生产的关键地理区域。柳枝（（Panicum virgatum）被广泛认为是碳（C）中性或C负生物能源生产系统，但是由于气候变化而导致的气温和降水预计增加可能会大大改变土壤有机碳（SOC）的动态和在土壤中的存储。这项研究检查了在当前和预期气候下在USGLR边缘土地上生长的柳枝long的长期SOC变化，并使用基于过程的模型（土地利用可持续性的系统方法）进行了预测，并对该模型进行了广泛校准，并对该模型进行了大量校准，九个实验点。模拟表明这些土壤可能是柳枝under下的净碳汇（平均增益为0.87 Mg C ha ^-1 - ^1年），尽管预测SOC累积速率会有很大变化（范围：0.2–1.3 Mg C ha - ¹ 年^-1）。主成分分析表明，SOC封存中预测的站点间变异部分与气候特征的差异有关，而在较小程度上与非均质土壤有关。尽管预计气候变化对柳枝plant植物生长的影响很小（平均下降4％–6％），但在最极端的情况下，土壤呼吸的增加预计会部分地使SOC积累降低到低于历史水平的70％。在预计的气候条件下，增加氮肥施用量和降低收获强度对SOC固存都有一定的好处，而引入更适合较长生长季节的基因型则是更为有效的策略。表现最佳的适应方案能够抵消超过60％的气候变化影响，从而导致SOC隔离0.7 Mg C ha^-1 年^-1在预计的气候下。平均而言，这比无适应基线多吸收了0.3 Mg C ha - ¹ 年^-1的C。这些发现提供了指导政策和运营管理所需的关键知识，以最大程度地限制USGLR边缘地区未来生物能源生产的SOC封存。