摘要:凋落物分解速率及其温度敏感性Q₁₀能够影响凋落物对土壤的碳归还及其对全球变暖的响应。然而，凋落物有机碳质量对凋落物分解及其温度敏感性的影响研究仍不充分。以黄河三角洲芦苇（Phragmites australi）为例，通过凋落物袋法、室内模拟实验及固态¹³C核磁共振技术，研究有机碳质量对凋落物分解及其温度敏感性的影响，探讨预测凋落物分解及其温度敏感性的指标。结果表明：（1）随着凋落物分解，易分解碳组分（烷氧碳、双烷氧碳）相对含量逐渐降低，而难分解碳组分（芳香碳）相对含量显著增加，疏水碳/亲水碳、芳香碳/烷氧碳比值逐渐增大，凋落物有机碳更加稳定，凋落物呼吸速率及失重率呈下降趋势。（2）凋落物失重主要受烷基碳、烷氧碳相对含量及C/N的影响，凋落物CO₂累积释放量主要受烷氧碳及双烷氧碳相对含量的影响。羰基碳相对含量可以用来解释Q₁₀的变异。因此，相对于生态化学计量比，烷基碳、烷氧碳、双烷氧碳、羰基碳相对含量是预测凋落物分解及其温度敏感性的敏感性指标。



Abstract:The decomposition rate of litter and its temperature sensitivity Q₁₀ could affect the return of organic carbon to the soil, and in turn, its response to global warming. However, exactly how the quality of organic carbon affects litter decomposition and its temperature sensitivity is still relatively unknown. In this study, field and laboratory incubation experiments were conducted to investigate how the quality of organic carbon affects litter decomposition and its temperature sensitivity. The leaf litter of reed (Phragmites australi) was collected in the Yellow River Delta, China, and the quality of organic carbon was assessed through solid-state ¹³C nuclear magnetic resonance spectroscopy (¹³C NMR). The results showed that (1) the relative abundance of O-alkyl and di-O-alkyl C was reduced, and the relative abundance of aromatic C was increased following litter decomposition. The ratios of hydrophobic to hydrophilic C and aromatic to O-alkyl C were also increased at the last stage of litter decomposition. These results indicate that the stability of organic carbon was enhanced during litter decomposition. The respiration and mass loss rate of litter also decreased during litter decomposition, and (2) the mass loss of litter was mainly controlled by the relative abundance of alkyl and O-alkyl C and C/N, whereas the cumulative CO₂ production of litter was mainly controlled by the relative abundance of O-alkyl and di-O-alkyl C. Furthermore, the Q₁₀ value of CO₂ production was affected by the relative abundance of carboxyl C. In general, the relative abundance of alkyl, O-alkyl, di-O-alkyl, and carboxyl C are more effective in predicting litter decomposition and its temperature sensitivity compared to litter stoichiometry.





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