Is litter decomposition enhanced in species mixtures? A meta-analysis
Is litter decomposition enhanced in species mixtures? A meta-analysis
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DOI：
10.1016/j.soilbio.2020.107791
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发表时间：
2020-06-01
影响因子：
9.7
通讯作者：
Hoffland, Ellis
中科院分区：
文献类型：
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作者：
Porre, Rima J.;van der Werf, Wopke;Hoffland, Ellis
凋落物分解是土壤碳平衡的关键过程。通常，植物凋落物以混合物的形式出现，其中物种在质量性状如营养浓度和有机碳质量方面存在差异。许多研究探讨，如果混合凋落物延迟或加速凋落物分解相比，单独分解的物种，有不同的结果。为了确定与总体定量合成一致的趋势，我们在荟萃分析中测试了两种植物物种的混合凋落物的质量损失是否平均比单一凋落物的平均质量损失快。我们假设，较大的性状差异的凋落物质量的物种在混合物中的混合物的质量损失比预期的单一物种的基础上更快的结果。此外，我们假设凋落物混合物质量损失的变化的一部分可以解释实验设计和环境因素。解释变量包括C、N、P、木质素、纤维素、酚类物质含量的化学凋落物特性差异以及土壤性质、生态系统、气候、凋落物分解持续时间和试验设计。相互作用进行了研究，如果支持的机制假设。在大多数研究中，平均而言，我们发现混合窝的质量损失等于组成单窝质量损失的加权平均值。没有一个假设的解释变量始终与窝混合物对质量损失的影响相关，并且显著模型的质量损失的解释变化总是仅占所有变化的百分之几。虽然进一步的数据探索可能会进一步阐明互动模式，但由于缺乏数据，其中许多模式无法探索。因此，这项荟萃分析驳斥了混合垃圾通常会提高分解率的观点。我们的结论是，在许多情况下，凋落物混合的影响是可预测的个别物种的分解率。根据我们的研究结果，凋落物物种之间的任何相互作用的影响（积极或消极）是上下文，不能概括和预测超出的背景下，获得的结果。
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 metaanalysis 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.