Functional dissimilarity across trophic levels as a driver of soil processes in a Mediterranean decomposer system exposed to two moisture levels
Functional dissimilarity across trophic levels as a driver of soil processes in a Mediterranean decomposer system exposed to two moisture levels
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DOI：
10.1111/oik.01917
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发表时间：
2015-10-01
期刊：
影响因子：
3.4
通讯作者：
Haettenschwiler, Stephan
中科院分区：
文献类型：
--
作者：
Coulis, Mathieu;Fromin, Nathalie;Haettenschwiler, Stephan
生物多样性对土壤过程的作用仍然知之甚少。现有证据表明，与土壤功能相关的是功能多样性，而不是物种丰富度。然而，很少在一个以上的营养水平上同时评估功能多样性的重要性，这严重限制了对生物多样性丧失对土壤功能后果的预测。在实验室微观实验中，我们验证了一个假设，即增加凋落物取食土壤动物和凋落物混合物的功能差异会相互影响与凋落物分解相关的五种不同土壤过程的速率。利用法国南部地中海灌丛生态系统中常见的两种腐植物的5种组合和两种凋落物的5种混合物，建立了基于性状的功能差异梯度。随着未来地中海生态系统干旱期的增加，我们增加了两种不同的浇水频率来评估干旱对土壤过程的影响以及干旱如何与功能差异相互作用。不同的动物组合和凋落物组合对凋落物质量损失、土壤有机碳和氮淋失以及土壤微生物活动有较强的影响。多达20%的响应变量的变化可以用功能差异来解释，这表明功能多样性对土壤过程速率的生态相关影响。当凋落物的多样性增加时，食腐物功能差异的影响更大，这表明性状差异在营养水平上相互作用。干旱影响了几个土壤过程，但没有改变功能差异与过程速率之间的关系。研究结果表明，腐殖物组合和凋落物混合物的性状多样性是土壤过程速率的重要预测因子。我们研究中使用的常见且易于测量的特征表明，可以直接应用于不同类型的生态系统和环境条件。
The role of biodiversity for soil processes remains poorly understood. Existing evidence suggests that functional diversity rather than species richness is relevant for soil functioning. However, the importance of functional diversity has rarely been assessed simultaneously at more than one trophic level, critically limiting the prediction of consequences of biodiversity loss for soil functioning. In a laboratory microcosm experiment, we tested the hypothesis that increasing functional dissimilarity of both litter-feeding soil fauna and litter mixtures interactively affects the rates of five different soil processes related to litter decomposition. We created trait-based functional dissimilarity gradients using five assemblages of two detritivore species and five mixtures of two plant litter species commonly found in Mediterranean shrubland ecosystems of southern France. With increasing drought periods predicted for Mediterranean ecosystems in the future, we additionally included two different watering frequencies to evaluate the impact of drought on soil processes and how drought interacts with functional dissimilarity. The different fauna assemblages and litter mixtures showed strong effects on litter mass loss, soil organic carbon and nitrogen leaching, as well as on soil microbial activities. Up to 20% of the variation in response variables was explained by functional dissimilarity, suggesting an ecologically relevant impact of functional diversity on soil process rates. Detritivore functional dissimilarity tended to have stronger effects when combined with increasingly dissimilar litter mixtures, suggesting that trait dissimilarity interacts across trophic levels. Drought affected several soil processes but did not modify the relationships between functional dissimilarity and process rates. Our results indicate that trait diversity of detritivore assemblages and litter mixtures is an important predictor of soil process rates. The common and easily measurable traits used in our study suggest straightforward application across different types of ecosystems and environmental conditions.