Litter decomposition is a key process in the carbon balance of soils. Commonly, plant litters occur in mixtures where the species differ in quality traits such as the nutrient concentration and organic carbon quality. Many studies explored if mixing litters retards or speeds up litter decomposition compared to species decomposing alone, with varying results. To identify consistent trends with an overarching quantitative synthesis, we test in a meta-analysis whether on average across studies, the mass loss of mixed litters of two plant species is faster than the average mass loss of single litters. We hypothesise that larger trait divergence of the litter quality of the species in a mixture results in a faster mass loss of the mixture than expected based on the single species. Furthermore we hypothesise that part of the variation in litter mixture mass loss can be explained by experimental design and environmental factors. Explanatory variables used were chemical litter trait dissimilarity in the C, N, P, lignin, cellulose, phenolics concentration as well as soil properties, ecosystem, climate, the duration of litter decomposition and the experimental design. Interactions were studied if supported by mechanistic hypotheses. In the majority of studies and on average, we found that the mass loss of mixed litters is equal to the weighted average of the mass loss of the constituent single litters. None of the hypothesised explanatory variables was consistently associated with litter mixture effects on the mass loss and explained variation in mass loss of significant models was invariably only a few percent of all variation. While further data exploration might elucidate further, interactive, patterns, many of these could not be explored due to lacking data. This meta-analysis therefore refutes the notion that mixing litters in general enhances rates of decomposition. We conclude that the effects of litter mixing are in many cases predictable from the decomposition rates of the individual species. According to our results, any interactive effects (positive or negative) between litter species are contextual, and cannot be generalized and predicted beyond the context in which the results were obtained.

凋落物分解是土壤碳平衡的关键过程。通常，植物凋落物会以混合物的形式出现，其中物种的品质性状（例如营养物浓度和有机碳质量）有所不同。许多研究探讨了与单独分解的物种相比，混合凋落物是否会延迟或加速凋落物的分解，从而产生不同的结果。为了通过总体定量综合方法确定一致的趋势，我们在荟萃分析中测试了研究平均而言，两种植物混合凋落物的质量损失是否快于单个凋落物的平均质量损失。我们假设混合物中物种凋落物质量的较大性状差异导致混合物的质量损失快于基于单一物种的预期质量损失。此外，我们假设垫料混合物质量损失的部分变化可以通过实验设计和环境因素来解释。所使用的解释变量是碳，氮，磷，木质素，纤维素，酚类浓度以及土壤性质，生态系统，气候，凋落物分解的持续时间和实验设计方面的化学凋落物性状差异。如果有机制假设的支持，则对相互作用进行了研究。在大多数研究中，平均而言，我们发现混合垫料的质量损失等于单个垫料的质量损失的加权平均值。假设的解释变量都没有与垃圾混合物对质量损失的影响一致，解释的重要模型的质量损失变化始终只是所有变化的百分之几。尽管进一步的数据探索可能会阐明进一步的交互模式，但由于缺乏数据而无法探索其中的许多模式。因此，这种荟萃分析驳斥了这样的观点，即混合使用垃圾可提高分解速度。我们得出的结论是，在许多情况下，凋落物混合的影响是可以根据单个物种的分解速率预测的。根据我们的结果，垫料物种之间的任何交互作用（正向或负向）都是上下文相关的，并且不能在获得结果的上下文之外进行概括和预测。我们得出的结论是，在许多情况下，凋落物混合的影响是可以根据单个物种的分解速率预测的。根据我们的结果，垫料物种之间的任何交互作用（正向或负向）都是上下文相关的，并且不能在获得结果的上下文之外进行概括和预测。我们得出的结论是，在许多情况下，凋落物混合的影响是可以根据单个物种的分解速率预测的。根据我们的结果，垫料物种之间的任何交互作用（正向或负向）都是上下文相关的，并且不能在获得结果的上下文之外进行概括和预测。