Wang Qing, Wang Dan, Wen Xuefa, Yu Guirui, He Nianpeng, Wang Rongfu
Resources and Environment College, Anhui Agricultural University, Hefei, China; Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
Resources and Environment College, Anhui Agricultural University, Hefei, China.
PLoS One. 2015 Feb 18;10(2):e0117033. doi: 10.1371/journal.pone.0117033. eCollection 2015.
The principle of enzyme kinetics suggests that the temperature sensitivity (Q10) of soil organic matter (SOM) decomposition is inversely related to organic carbon (C) quality, i.e., the C quality-temperature (CQT) hypothesis. We tested this hypothesis by performing laboratory incubation experiments with bulk soil, macroaggregates (MA, 250-2000 μm), microaggregates (MI, 53-250 μm), and mineral fractions (MF, <53 μm) collected from an Inner Mongolian temperate grassland. The results showed that temperature and aggregate size significantly affected on SOM decomposition, with notable interactive effects (P<0.0001). For 2 weeks, the decomposition rates of bulk soil and soil aggregates increased with increasing incubation temperature in the following order: MA>MF>bulk soil >MI(P <0.05). The Q10 values were highest for MA, followed (in decreasing order) by bulk soil, MF, and MI. Similarly, the activation energies (Ea) for MA, bulk soil, MF, and MI were 48.47, 33.26, 27.01, and 23.18 KJ mol-1, respectively. The observed significant negative correlations between Q10 and C quality index in bulk soil and soil aggregates (P<0.05) suggested that the CQT hypothesis is applicable to soil aggregates. Cumulative C emission differed significantly among aggregate size classes (P <0.0001), with the largest values occurring in MA (1101 μg g-1), followed by MF (976 μg g-1) and MI (879 μg g-1). These findings suggest that feedback from SOM decomposition in response to changing temperature is closely associated withsoil aggregation and highlights the complex responses of ecosystem C budgets to future warming scenarios.
酶动力学原理表明，土壤有机质（SOM）分解的温度敏感性（Q10）与有机碳（C）质量呈负相关，即碳质量-温度（CQT）假说。我们通过对从内蒙古温带草原采集的原状土、大团聚体（MA，250 - 2000μm）、微团聚体（MI，53 - 250μm）和矿物组分（MF，<53μm）进行实验室培养实验来验证这一假说。结果表明，温度和团聚体大小对SOM分解有显著影响，且存在显著的交互作用（P<0.0001）。在为期2周的实验中，原状土和土壤团聚体的分解速率随培养温度升高而增加，顺序如下：MA>MF>原状土>MI（P<0.05）。MA的Q10值最高，其次（按降序排列）是原状土、MF和MI。同样，MA、原状土、MF和MI的活化能（Ea）分别为48.47、33.26、27.01和23.18 KJ mol-1。在原状土和土壤团聚体中观察到的Q10与碳质量指数之间显著的负相关（P<0.05）表明CQT假说适用于土壤团聚体。累积碳排放量在不同团聚体大小类别之间存在显著差异（P<0.0001），最大值出现在MA中（1101μg g-1），其次是MF（976μg g-1）和MI（879μg g-1）。这些发现表明，SOM分解对温度变化的反馈与土壤团聚密切相关，并突出了生态系统碳收支对未来变暖情景的复杂响应。
