Dynamics of soil CO2 efflux under varying atmospheric CO2 concentrations reveal dominance of slow processes
Dynamics of soil CO2 efflux under varying atmospheric CO2 concentrations reveal dominance of slow processes
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DOI：
10.1111/gcb.13713
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发表时间：
2017-09
影响因子：
11.6
通讯作者：
Dohyoung Kim;R. Oren;James S. Clark;S. Palmroth;A. C. Oishi;H. McCarthy;C. Maier;K. Johnsen
中科院分区：
文献类型：
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作者：
Dohyoung Kim;R. Oren;James S. Clark;S. Palmroth;A. C. Oishi;H. McCarthy;C. Maier;K. Johnsen
我们通过改变 15 年+200 ppmv 环境下的 CO2 浓度，评估了光合速率突然变化对土壤 CO2 流出量 (FCO2) 的影响。每隔五天暴露于环境浓度 1.0-1.8 倍的升高的 CO2 (eCO2) 环境中不会影响 FCO2。直到长期 eCO2 处理终止后 4 个月，FCO2 才下降，比实验性阻止碳流向地下后观察到的 FCO2 下降 10 天长，但比开始 eCO2 后 FCO2 增加所需的约 13 个月短。富集终止后 FCO2 的减少（~35%）不能用叶面积（~15%）和相关碳水化合物生产和分配的减少来解释，这表明地下生态系统组成部分不成比例地收缩；这与基础呼吸和 FCO2 温度敏感性的降低是一致的。这些不对称响应对试图隔离单个过程对 FCO2 影响的基于过程的模型提出了易于处理的挑战。
We evaluated the effect on soil CO2 efflux (FCO2) of sudden changes in photosynthetic rates by altering CO2 concentration in plots subjected to +200 ppmv for 15 years. Five‐day intervals of exposure to elevated CO2 (eCO2) ranging 1.0–1.8 times ambient did not affect FCO2. FCO2 did not decrease until 4 months after termination of the long‐term eCO2 treatment, longer than the 10 days observed for decrease of FCO2 after experimental blocking of C flow to belowground, but shorter than the ~13 months it took for increase of FCO2 following the initiation of eCO2. The reduction of FCO2 upon termination of enrichment (~35%) cannot be explained by the reduction of leaf area (~15%) and associated carbohydrate production and allocation, suggesting a disproportionate contraction of the belowground ecosystem components; this was consistent with the reductions in base respiration and FCO2‐temperature sensitivity. These asymmetric responses pose a tractable challenge to process‐based models attempting to isolate the effect of individual processes on FCO2.