摘要:土壤有机碳矿化是调节温室气体排放、土壤有机质形成以及土壤生物和植物营养供应的重要过程，植物残体分解释放CO₂对土壤有机碳矿化有着重要影响。通过对科尔沁沙地沙丘草地4种优势植物叶凋落物的混合培养试验，测定了凋落物培养过程中CO₂释放速率及其累积释放量，比较了混合凋落物CO₂释放量实测值与预测值的差异，分析了凋落物化学成分和物种多样性（包括物种丰富度和物种组成）与土壤有机碳矿化的相关关系，以期解释添加混合凋落物对土壤有机碳矿化的影响。结果表明，混合凋落物物种丰富度对土壤有机碳矿化的影响不显著，而凋落物一些化学性质与土壤有机碳矿化紧密相关；所有混合组合处理中，80%的凋落物组合处理对土壤有机碳矿化产生显著（P < 0.05）的非加和效应；氮含量较高的豆科植物达乌里胡枝子凋落物与禾本科植物凋落物混合后土壤有机碳矿化表现极显著（P < 0.001）的协同非加和效应，而禾本科植物凋落物交互混合后土壤有机碳矿化产生显著拮抗非加和效应，这可能是凋落物化学成分相似或凋落物叶片的空间异质性引起的。



Abstract:The mineralization of organic carbon in soil is an important process that regulates greenhouse gas emissions, soil organic matter formation, and nutrient availability for soil biota and plants. The decomposition and release of CO₂ from plant residue are important processes that affect soil organic carbon mineralization, and many studies have explored the changes in soil organic carbon following litter addition; however, these studies focus on the effects of single type of litter addition and failed to consider the effects of mixed litter. In both natural and managed ecosystems, plant litter, with different chemical compositions, generally become mixed by the influence of wind, water, or humans, and animals influence the degradation process of organic matter in the soil. Hence, examining the effects of the chemical traits of litter mixtures and litter species diversity on the mineralization of soil organic carbon is of considerable importance. In this study, litters of typical plants Setaria viridis, Phragmites communis Trin, Cleistogenes squarrosa, Lespedeza davurica, and sandy soil from the Horqin dune grassland was collected and incubated in a laboratory for 95 days. In order to explain the effects of mixed-species litter on soil organic carbon mineralization, four single litter species and their mixtures, consisting of all possible 2-, 3-and 4-species combinations, were added to soil in jars. We described the dynamics of organic carbon mineralization rates and calculated the cumulative release of CO₂ for all treatments and the difference between measured and predicted effects for the litter mixture. We also explored the effects of chemical traits and species diversity on soil organic carbon mineralization. The results showed that soil organic carbon mineralization was not influenced by the richness of the litter mixture but was closely related to the litter chemical properties, such as N, C/N, lignin/N, and LOMⅠcontents. This suggests that compared with litter mixture with few species, mixed litter with higher species diversity might have functional redundancy. In most instances, species mixing produced no-additive effect on soil organic carbon mineralization, and synergistic non-additive effects were more common than antagonistic non-additive effects, with 7 vs. 2. When the Lespedeza davurica litter was mixed with the gramineous plant litter, soil organic carbon mineralization showed synergistic effects. When the gramineous plant litter was mixed, soil organic carbon mineralization was antagonistic. This might be in part attributed to the similarity of litter chemical composition between the two litter types or from the spatial heterogeneity of the leaf litter.





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