Data from: Recasting the dynamic equilibrium model through a functional lens: the interplay of trait-based community assembly and climate

1. According to the dynamic equilibrium hypothesis (DEH), plant species richness is locally controlled by productivity and disturbance. Given that regional conditions widely affect local environmental variables such as soil nutrient availability, the DEH predictions could be improved by considering how climate influences local controls of species richness. Further, a trait-based approach to community assembly has the potential to reveal a deeper, mechanistic understanding of species richness variation across environments. Here we bring together DEH and trait-based community assembly expectations to examine if and how local relationships between diversity, disturbance and productivity are affected by habitat filtering and regional climate. 2. We specifically tested how gradients of local nutrient availability and disturbance intensity interact with climatic conditions to drive the species richness of grassland communities. Further, we recast the DEH through a functional lens by exploring how disturbance-diversity and nutrient availability-diversity relationships are shaped by the functional space occupied by species in a community and species packing within this functional space. 3. The functional space occupied by co-occurring species and the way they are functionally packed are quantified using multi-trait indices calculated with five core plant functional traits. Working with grassland communities spread across differing regional climatic conditions, we used mixed models to test if the variation in taxonomic and functional metrics corresponded to the dynamic equilibrium model's predictions as well as to determine the relationship between those metrics. 4. Contrary to the expectations based on the relation between species richness and the functional components considered, taxonomic and functional metrics did not vary in accordance along environmental gradients. Climate strongly interacted with the local environment to modulate local diversity patterns, sometimes even inversing a given trend and falsifying the DEH predictions. 5. Synthesis. Our findings quantitatively highlight the interplay between regional and local environmental gradients in driving community assembly. We demonstrate that, depending on climatic conditions, observed patterns of both taxonomic and functional community composition can be opposite to expected productivity-diversity and disturbance-diversity relationships. This emphasizes the relevance of multi-faceted studies of biodiversity and the need for a more systematic quantification of regional controls in community assembly studies.

1. 动态平衡假说（Dynamic Equilibrium Hypothesis, DEH）提出，植物物种丰富度在局域尺度上受生产力与干扰的共同调控。鉴于区域环境条件会广泛影响土壤养分有效性等局域环境变量，若纳入气候对物种丰富度局域调控过程的影响，可优化动态平衡假说的预测效能。此外，面向群落构建的基于性状的研究方法，有望揭示不同环境下物种丰富度变异的深层机制性认知。本研究整合动态平衡假说与基于性状的群落构建理论预期，旨在探究多样性、干扰与生产力之间的局域关联是否受生境过滤与区域气候的调控，以及具体的作用路径。
2. 本研究专门检验了局域养分有效性梯度与干扰强度梯度如何与气候条件相互作用，进而驱动草原群落的物种丰富度格局。此外，本研究从功能性状视角重新阐释动态平衡假说：通过探究群落内物种占据的功能空间，以及该功能空间内的物种充填（species packing）情况，解析干扰-多样性与养分有效性-多样性关系的形成机制。
3. 本研究利用基于5种核心植物功能性状（plant functional traits）计算得到的多性状指数，对共存物种占据的功能空间及其功能充填方式进行量化。本研究以分布于不同区域气候背景下的草原群落为研究对象，采用混合效应模型（mixed models）检验分类学与功能学指标的变异是否符合动态平衡模型的预测结果，并明确两类指标间的关联关系。
4. 与基于物种丰富度与所考量的功能组分之间关联的预期相悖，分类学与功能学指标并未随环境梯度呈现一致的变化规律。气候与局域环境存在强烈的交互作用，进而调控局域多样性格局，有时甚至会逆转既定趋势，证伪动态平衡假说的预测结果。
5. 综合与结论：本研究的结果定量阐明了区域与局域环境梯度在调控群落构建过程中的交互作用。研究表明，受气候条件的影响，观测得到的分类学与功能学群落组成格局，可能与预期的生产力-多样性及干扰-多样性关系相悖。这一结果凸显了生物多样性多维度研究的重要性，同时也指出在群落构建研究中，需要更系统地量化区域环境的调控作用。