Data from: Shifts and linkages of functional diversity between above- and below-ground compartments along a flooding gradient

1. Trait-based approaches have the potential to reveal general and predictive relationships between organisms and ecosystem functioning. However the mechanisms underlying the functional structure of communities are still unclear. Within terrestrial ecosystems several studies have shown that many ecological processes are controlled by the interacting above and belowground compartments. However, few studies have used traits to reveal functional relationships between plants and soil fauna. Mostly, research combining plants and soil fauna solely used the traits of one assemblage in predictive studies.

2. Above (plants) and belowground (Collembola) compartments were sampled over a flooding gradient in northern France along the Seine River. First, we measured the effect of flooding on functional and taxonomic assembly within both communities. We then considered the linkages between plant and Collembolan species richness, community traits and assessed whether traits of both compartments converged at high flooding intensity (abiotic filtering) and diverged when this constraint is released (biotic filter).

3. Species richness of both taxa followed the same bell-shaped pattern along the gradient while a similar significant pattern of functional richness was only observed for plants. Further analyses revealed a progressive shift from trait convergence to divergence for plants but not for Collembola as constraints intensity decreased.. Instead, our results highlighted that Collembola traits were mainly linked to variations in plant traits. This lead, within Collembola assemblages, to convergence of a subset of perception and habitat-related traits for which the relationship with plant traits was assessed.

4. Synthesis: Using a trait-based approach, our study highlighted that functional relationships occur between above and belowground compartments. We underlined that plant communities functional composition plays a key role in structuring Collembola assemblages in addition to the role of abiotic variables. Our study clearly shows that functional diversity provides a new approach to link the above and belowground compartments and might, therefore, be further considered when studying ecological processes at the interface between both compartments.

1. 基于功能性状的研究方法有望揭示生物与生态系统功能之间通用且可预测的关联。然而，群落功能结构背后的调控机制仍未明确。在陆地生态系统中，多项研究已证实诸多生态过程受地上与地下生态组分的交互作用调控。但目前鲜有研究通过功能性状来揭示植物与土壤动物之间的功能关联。绝大多数结合植物与土壤动物的预测类研究，仅采用了其中一类生物集合的功能性状。
2. 本研究沿法国北部塞纳河沿线的洪水梯度对地上（植物）与地下（弹尾纲（Collembola））组分进行了采样。首先，我们分析了洪水对两类群落的功能组装与分类群组装的影响；随后，我们探究了植物与弹尾纲物种丰富度、群落功能性状之间的关联，并评估了两类组分的性状是否在高洪水强度下（即非生物过滤作用下）发生趋同，而在该约束解除时发生分化（即生物过滤作用下）。
3. 两类类群的物种丰富度沿该梯度均呈现一致的钟形分布模式，但功能丰富度的相似显著模式仅在植物类群中被观测到。进一步分析显示，随着约束强度降低，植物类群的功能性状呈现出从趋同向分化的渐进式转变，而弹尾纲则未出现该规律。与之相反，本研究结果表明弹尾纲的功能性状主要与植物性状的变异相关联。这一关联使得弹尾纲群落中感知相关与栖息地相关的性状子集发生趋同，本研究同时评估了该类性状与植物性状之间的关联。
4. 综合与结论：本研究基于功能性状方法，证实了地上与地下生态组分之间存在功能关联。研究明确指出，除非生物变量的作用外，植物群落的功能组成在弹尾纲群落的结构构建中同样发挥关键作用。本研究清晰表明，功能多样性为地上与地下生态组分的关联研究提供了全新思路，因此在探究两类组分界面处的生态过程时，可进一步考虑采用功能多样性研究方法。