Data from: Pyramids of species richness: the determinants and distribution of species diversity across trophic levels

How species richness is distributed across trophic levels determines several dimensions of ecosystem functioning, including herbivory, predation, and decomposition rates. We perform a meta-analysis of 72 large published food webs to investigate their trophic diversity structure and possible endogenous, exogenous, and methodological causal variables. Consistent with classic theory, we found that published food webs can generally be described as ‘pyramids of species richness’. The food webs were more predator-poor, prey-rich and hierarchical than is expected by chance or by the niche or cascade models. The trophic species richness distribution also depended on centrality, latitude, ecosystem-type and methodological bias. Although trophic diversity structure is generally pyramidal, under many conditions the structure is consistently uniform or inverse-pyramidal. Our meta-analysis adds nuance to classic assumptions about food web structure: diversity decreases with trophic level, but not under all conditions, and the decrease may be scale-dependent.

物种丰富度沿营养级的分布格局，决定了生态系统功能的多个维度，包括植食作用、捕食作用以及分解速率。本研究对72个已发表的大型食物网（food web）开展元分析，以探究其营养多样性结构，以及可能存在的内源性、外源性与方法学层面的因果变量。与经典理论相符，我们发现已发表的食物网整体上可被描述为‘物种丰富度金字塔’。相较于随机过程、生态位模型或级联模型的预期结果，这些食物网更偏向于捕食者匮乏、猎物富集且具有层级结构的特征。物种丰富度的营养级分布还受到中心性、纬度、生态系统类型以及方法学偏差的影响。尽管营养多样性结构整体呈金字塔形，但在诸多条件下，其结构会持续呈现均匀分布或倒金字塔形态。本元分析为食物网结构的经典假设增添了细节：物种多样性随营养级升高而降低的规律并非适用于所有场景，且这种降低趋势可能存在尺度依赖性。