Data from: Eating up the world's food web and the human trophic level

Trophic levels are critical for synthesizing species’ diets, depicting energy pathways, understanding food web dynamics and ecosystem functioning, and monitoring ecosystem health. Specifically, trophic levels describe the position of species in a food web, from primary producers to apex predators (range, 1–5). Small differences in trophic level can reflect large differences in diet. Although trophic levels are among the most basic information collected for animals in ecosystems, a human trophic level (HTL) has never been defined. Here, we find a global HTL of 2.21, i.e., the trophic level of anchoveta. This value has increased with time, consistent with the global trend toward diets higher in meat. National HTLs ranging between 2.04 and 2.57 reflect a broad diversity of diet, although cluster analysis of countries with similar dietary trends reveals only five major groups. We find significant links between socio-economic and environmental indicators and global dietary trends. We demonstrate that the HTL is a synthetic index to monitor human diets and provides a baseline to compare diets between countries.

营养级（trophic levels）对于整合物种食谱、刻画能量流动路径、解析食物网动态与生态系统功能，以及监测生态系统健康均具有关键意义。具体而言，营养级描述了物种在食物网中的位置，跨度从初级生产者到顶级捕食者（范围为1至5）。营养级的微小差异，即可反映食谱的显著差异。尽管营养级是生态系统中动物研究的最基础观测信息之一，但人类营养级（human trophic level, HTL）此前从未被明确界定。本研究测得全球人类营养级为2.21，即鳀鱼（anchoveta）的营养级水平；该数值随时间推移呈上升趋势，与全球人类食谱肉类占比升高的整体趋势相符。各国人类营养级介于2.04至2.57之间，反映出全球食谱的广泛多样性；而对饮食趋势相似的国家进行聚类分析后，仅识别出5个主要群组。本研究发现社会经济与环境指标和全球饮食趋势之间存在显著关联。研究证实，人类营养级是监测人类食谱的综合指标，同时可为跨国食谱对比提供基准参照。