Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA.
Department of Botany and Microbiology, University of Oklahoma, Norman, OK, 73019-0245, USA.
Glob Chang Biol. 2015 Dec;21(12):4293-7. doi: 10.1111/gcb.13074.
Elevated atmospheric CO2 concentrations increase plant productivity and affect soil microbial communities, with possible consequences for the turnover rate of soil carbon (C) pools and feedbacks to the atmosphere. In a previous analysis (Van Groenigen et al., 2014), we used experimental data to inform a one-pool model and showed that elevated CO2 increases the decomposition rate of soil organic C, negating the storage potential of soil. However, a two-pool soil model can potentially explain patterns of soil C dynamics without invoking effects of CO2 on decomposition rates. To address this issue, we refit our data to a two-pool soil C model. We found that CO2 enrichment increases decomposition rates of both fast and slow C pools. In addition, elevated CO2 decreased the carbon use efficiency of soil microbes (CUE), thereby further reducing soil C storage. These findings are consistent with numerous empirical studies and corroborate the results from our previous analysis. To facilitate understanding of C dynamics, we suggest that empirical and theoretical studies incorporate multiple soil C pools with potentially variable decomposition rates.
大气中二氧化碳浓度的升高会提高植物的生产力，并影响土壤微生物群落，这可能会影响土壤碳（C）库的周转率，并对大气产生反馈。在之前的分析（Van Groenigen 等人，2014 年）中，我们使用实验数据为一个单库模型提供了信息，并表明升高的 CO2 会增加土壤有机 C 的分解速率，从而否定了土壤的储存潜力。然而，双库土壤模型可以在不考虑 CO2 对分解速率影响的情况下，潜在地解释土壤 C 动态的模式。为了解决这个问题，我们重新拟合了我们的数据到一个双库土壤 C 模型中。我们发现，CO2 富集增加了快和慢 C 库的分解速率。此外，升高的 CO2 降低了土壤微生物的碳利用效率（CUE），从而进一步减少了土壤 C 的储存。这些发现与众多经验研究一致，并证实了我们之前分析的结果。为了便于理解 C 动态，我们建议经验和理论研究纳入具有潜在可变分解速率的多个土壤 C 库。
