Wu Dan, Xu Chi, Wang Shaopeng, Zhang Lai, Kortsch Susanne
School of Mathematical Science, Yangzhou University, Yangzhou, China.
Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China.
J Anim Ecol. 2023 Feb;92(2):367-376. doi: 10.1111/1365-2656.13808. Epub 2022 Sep 11.
The relationship between biodiversity and ecosystem functions (BEFs) has attracted great interest. Studies on BEF have so far focused on the average trend of ecosystem function as species diversity increases. A tantalizing but rarely addressed question is why large variations in ecosystem functions are often observed across systems with similar species diversity, likely obscuring observed BEFs. Here we use a multi-trophic food web model in combination with empirical data to examine the relationships between species richness and the variation in ecosystem functions (VEFs) including biomass, metabolism, decomposition, and primary and secondary production. We then probe the mechanisms underlying these relationships, focusing on the role of trophic interactions. While our results reinforce the previously documented positive BEF relationships, we found that ecosystem functions exhibit significant variation within each level of species richness and the magnitude of this variation displays a hump-shaped relationship with species richness. Our analyses demonstrate that VEFs is reduced when consumer diversity increases through elevated nonlinearity in trophic interactions, and/or when the diversity of basal species such as producers and decomposers decreases. This explanation is supported by a 34-year empirical food web time series from the Gulf of Riga ecosystem. Our work suggests that biodiversity loss may not only result in ecosystem function decline, but also reduce the predictability of functions by generating greater function variability among ecosystems. It thus helps to reconcile the debate on the generality of positive BEF relationships and to disentangle the drivers of ecosystem stability. The role of trophic interactions and the variation in their strengths mediated by functional responses in shaping ecosystem function variation warrants further investigations and better incorporation into biodiversity-ecosystem functioning research.
生物多样性与生态系统功能（BEF）之间的关系引发了极大的关注。迄今为止，关于BEF的研究主要聚焦于随着物种多样性增加生态系统功能的平均趋势。一个引人入胜但很少被探讨的问题是，为什么在具有相似物种多样性的系统中，常常观察到生态系统功能存在巨大差异，这可能会掩盖所观察到的BEF关系。在此，我们使用一个多营养级食物网模型并结合实证数据，来研究物种丰富度与生态系统功能变化（VEF）之间的关系，这些功能包括生物量、新陈代谢、分解以及初级和次级生产。然后，我们探究这些关系背后的机制，重点关注营养相互作用的作用。虽然我们的结果强化了先前记录的正向BEF关系，但我们发现，在每个物种丰富度水平内，生态系统功能都表现出显著变化，且这种变化的幅度与物种丰富度呈现出驼峰状关系。我们的分析表明，当消费者多样性通过营养相互作用中更高的非线性增加时，和/或当生产者和分解者等基础物种的多样性降低时，VEF会降低。来自里加湾生态系统的一个34年的实证食物网时间序列支持了这一解释。我们的研究表明，生物多样性丧失不仅可能导致生态系统功能下降，还可能通过在生态系统之间产生更大的功能变异性来降低功能的可预测性。因此，它有助于调和关于正向BEF关系普遍性的争论，并厘清生态系统稳定性的驱动因素。营养相互作用的作用以及由功能反应介导的其强度变化在塑造生态系统功能变化中的作用，值得进一步研究，并更好地纳入生物多样性 - 生态系统功能研究中。
