Effect of dry-wet cycles on carbon dioxide release from two different volcanic ash soils in a Japanese temperate forest
Effect of dry-wet cycles on carbon dioxide release from two different volcanic ash soils in a Japanese temperate forest
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DOI：
10.1080/00380768.2019.1649976
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发表时间：
2019-08
影响因子：
2
通讯作者：
Hirohiko Nagano;M. Atarashi-Andoh;J. Koarashi
中科院分区：
文献类型：
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作者：
Hirohiko Nagano;M. Atarashi-Andoh;J. Koarashi
摘要在目前的研究中，两个火山灰土壤（土壤A和B）从温带阔叶林在日本东部有氧培养下反复干湿循环和连续恒定的湿度条件。主要目的是量化由于水波动增加而增加二氧化碳释放的潜力，并研究具有不同物理化学性质的火山灰土壤的反应差异。土壤B是典型的灰壤，而不是土壤A。在20°C下孵育120天并进行5次干湿循环期间，定期测量CO2释放速率。通过测定CO2中稳定碳同位素（δ 13 C-CO2）的变化，研究了干湿循环对土壤有机质分解的影响。干湿循环下的CO2释放速率高达49%，高于预测值从一个抛物线的CO2释放和水分含量在培养过程中的连续恒定的水分条件下的关系。土壤B中CO2释放的增加幅度是土壤A的2.7倍。干湿交替条件下的δ 13 C-CO2值比连续水分条件下的δ 13 C-CO2值增加了0.3-2.3‰，表明干湿交替促进了代谢较好和/或较老的有机质的分解。因此，本研究表明，被认为具有很强的有机质稳定能力的土壤，是容易受到干湿循环。那么，在未来更温暖的世界中，水波动的增加将有很大的潜力刺激土壤中的CO2释放。
ABSTRACT In the present study, two volcanic ash soils (soil A and B) from a temperate broad-leaved forest in eastern Japan were aerobically incubated under repeated dry-wet cycles and continuously constant moisture conditions. The primary aims were to quantify the potential for enhancement of carbon dioxide (CO2) release owing to increased water fluctuation and to examine differences in the responses of volcanic ash soils with different physicochemical properties. Soil B, rather than soil A, was a typical Andosol. During incubation at 20°C for 120 days with five dry-wet cycles, the CO2 release rate was measured periodically. Abundance of the stable carbon isotope in CO2 (δ13C-CO2) was measured to capture changes in the origin of decomposed soil organic matter (SOM) owing to the dry-wet cycles. The CO2 release rate under the dry-wet cycles was up to 49% higher than the values predicted from a parabolic relationship between CO2 release and water content during incubation under the continuously constant moisture condition. The magnitude of CO2 release enhancement was 2.7-fold higher in soil B relative to that in soil A. The δ13C-CO2 value in the dry-wet cycles was enriched by 0.3–2.3‰ compared to that during incubation under the continuously constant moisture conditions, suggesting that the decomposition of well-metabolized and/or old SOM was enhanced by the dry-wet cycles. Thus, the present study suggests that Andosols, which have been believed to have a strong SOM stabilization ability, are vulnerable to dry-wet cycles. Then, increased water fluctuation in a future warmer world would have significant potential to stimulate CO2 release from soils.