Data from: Decoupled diversity dynamics in green and brown webs during primary succession in a salt marsh

1. Terrestrial ecosystems are characterised by a strong functional connection between the green (plant-herbivore-based) and brown (detritus-detritivore-based) parts of the food web, which both develop over successional time. However, the interlinked changes in green and brown food web diversity patterns in relation to key ecosystem processes are rarely studied.

2. Here, we demonstrate changes in species richness, diversity and evenness over a wide range of invertebrate green and brown trophic groups during 100 years of primary succession in a salt marsh ecosystem, using a well-calibrated chronosequence.

3. We contrast two hypotheses on the relationship between green and brown food web diversity across succession: i) ‘coupled diversity hypothesis’, which predicts that all trophic groups covary similarly with the main drivers of successional ecosystem assembly versus ii) the ‘decoupled diversity hypothesis’, where green and brown trophic groups diversity respond to different drivers during succession.

4. We found that, while species richness for plants and invertebrate herbivores (green web groups) both peaked at intermediate productivity and successional age, the diversity of macro-detritivores, microarthropod microbivores and secondary consumers (brown web groups) continuously increased towards the latest successional stages. These results suggest that green web trophic groups are mainly driven by vegetation parameters, such as the amount of bare soil, vegetation biomass production, and vegetation height, while brown web trophic groups are mostly driven by the production and standing stock of dead organic material and soil development.

5. Our results show that plant diversity cannot simply be used as a proxy for the diversity of all other species groups that drive ecosystem functioning, as brown and green diversity components in our ecosystem responded differently to successional gradients.

1. 陆地生态系统的典型特征为，食物网的绿色基（以植物-植食动物为基础）与棕色基（以碎屑-碎屑食动物为基础）两大组分之间存在紧密的功能联系，二者均随演替时间推进而发育。然而，针对绿色与棕色食物网多样性格局随关键生态系统过程发生的联动变化，相关研究仍较为匮乏。
2. 本研究采用一套经过严格校准的年代序列（chronosequence），针对盐沼（salt marsh）生态系统长达百年的原生演替过程，剖析了多类无脊椎动物绿色与棕色营养类群的物种丰富度、多样性及均匀度变化。
3. 本研究对比了两套关于演替过程中绿色与棕色食物网多样性关系的假说：① 耦合多样性假说（coupled diversity hypothesis），该假说预测所有营养类群会随演替生态系统组装的核心驱动因子呈现相似的协同变化；② 解耦多样性假说（decoupled diversity hypothesis），该假说认为演替过程中绿色与棕色营养类群的多样性会响应不同的驱动因子。
4. 研究结果显示，植物与无脊椎动物植食者（绿色食物网类群）的物种丰富度均在中等生产力水平与演替年龄阶段达到峰值；而大型碎屑食动物、微型节肢动物食微者与次级消费者（棕色食物网类群）的多样性则随演替推进至后期阶段持续升高。上述结果表明，绿色食物网营养类群主要受植被参数调控，如裸土面积、植被生物量生产力及植被高度；棕色食物网营养类群则主要受死亡有机质的生产与现存量以及土壤发育过程驱动。
5. 本研究结果表明，不能简单将植物多样性作为所有驱动生态系统功能的其他物种类群多样性的替代指标，因为该生态系统中的棕色与绿色多样性组分对演替梯度的响应模式存在显著差异。