Microbial utilization of low molecular weight organic carbon substrates in cultivated peats in response to warming and soil degradation
Microbial utilization of low molecular weight organic carbon substrates in cultivated peats in response to warming and soil degradation
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DOI：
10.1016/j.soilbio.2019.107629
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发表时间：
2019-12
影响因子：
9.7
通讯作者：
Yuan Wen;H. Zang;B. Freeman;S. Musarika;C. Evans;D. Chadwick;Davey L. Jones
中科院分区：
文献类型：
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作者：
Yuan Wen;H. Zang;B. Freeman;S. Musarika;C. Evans;D. Chadwick;Davey L. Jones
泥炭地在全球陆地生物圈中储存了大量的碳（C）。泥炭土的排水和耕作导致土壤迅速退化和碳损失，在变暖的情况下，由于土壤不再受到厌氧条件的保护，这种情况可能会恶化。为了预测土壤碳流失的速率并设计有效的减缓策略，重要的是要了解是什么控制着这些土壤中的有机质矿化。使用0-10厘米的厚和薄（退化）农业泥炭土壤的土壤深度，我们调查的命运低分子量有机基质（LMWOS）和微生物生物量消耗这些基板如何响应温度。我们将土壤在逐渐升高的温度（4、10、20和30 °C）下培养72小时。将~（14）C标记的葡萄糖或氨基酸添加到土壤中，测定它们的分解速度、分解/同化过程和微生物碳利用效率（CUE）。在72小时的培养过程中，无论泥炭层的厚度，从土壤中的总14 CO2损失显着增加，随着温度的升高。变暖通过改变碳分配和不同微生物碳库的周转率改变了LMWOS矿化的动态。当温度从4 ° C升高到30 °C时，两种基质的LMWOS半衰期降低超过50%。泥炭土的CUE始终高于厚泥炭土，且均随温度升高而降低0.002-0.005 °C-1。薄泥炭减少基质C分配到快速循环的C池相比，厚泥炭，但没有整体效果池周转率。我们的工作表明，气候变暖将加速碳矿化和土壤流失排水泥炭土，与厚泥炭土预计更大的影响。这项研究提供了一个重要的第一步，在表征不稳定碳的微生物利用的温度变化和土壤退化的反应，在耕作泥炭地。
Peatlands store vast amounts of carbon (C) within the global terrestrial biosphere. Drainage and cultivation of peat soils lead to rapid soil degradation and C losses, and this may worsen under warming as the soils are no longer protected by anaerobic conditions. To predict the rates of soil C loss and design effective mitigation strategies, it is important to understand what controls organic matter mineralization in these soils. Using the 0–10 cm soil depth of thick and thin (degraded) agricultural peat soils, we investigated the fate of low molecular weight organic substrates (LMWOS) and how the microbial biomass consuming these substrates responded to temperature. We incubated the soils under increasing temperatures (4, 10, 20, and 30 °C) for 72 h. Either14C-labelled glucose or amino acids were added to the soils and their speed of breakdown, partitioning into anabolic/catabolic processes and microbial C use efficiency (CUE) were determined. The total14CO2loss from soil increased significantly with increasing temperature during 72-h incubation, regardless of peat layer thickness. Warming altered the dynamics of LMWOS mineralization by changing C allocation and the turnover rate of different microbial C pools. The half-life of LMWOS decreased more than 50% when temperature increased from 4 to 30 °C for both substrates. CUE was always higher for thin than thick peat soil and both declined by 0.002–0.005 °C-1with increasing temperature. Thin peat decreased substrate C allocation into the fast cycling C pool compared to the thick peat, but had no overall effect on pool turnover rate. Our work suggests that climate warming will accelerate C mineralization and soil loss in drained peat soils, with larger effects expected in thick peat soil. This study provides an important initial step in characterizing the response of the microbial utilization of labile C to temperature change and soil degradation in cultivated peatlands.