The relationship between biodiversity and biomass has been a long standing debate in ecology. Soil biodiversity and biomass are essential drivers of ecosystem functions. However, unlike plant communities, little is known about how the diversity and biomass of soil microbial communities are interlinked across globally distributed biomes, and how variations in this relationship influence ecosystem function. To fill this knowledge gap, we conducted a field survey across global biomes, with contrasting vegetation and climate types. We show that soil carbon (C) content is associated to the microbial diversity–biomass relationship and ratio in soils across global biomes. This ratio provides an integrative index to identify those locations on Earth wherein diversity is much higher compared with biomass and vice versa. The soil microbial diversity-to-biomass ratio peaks in arid environments with low C content, and is very low in C-rich cold environments. Our study further advances that the reductions in soil C content associated with land use intensification and climate change could cause dramatic shifts in the microbial diversity-biomass ratio, with potential consequences for broad soil processes.

生物多样性和生物量之间的关系一直是生态学中长期存在的争论。土壤生物多样性和生物量是生态系统功能的重要驱动力。然而，与植物群落不同，人们对土壤微生物群落的多样性和生物量如何在全球分布的生物群落中相互关联，以及这种关系的变化如何影响生态系统功能知之甚少。为了填补这一知识空白，我们对全球生物群落进行了实地调查，并对比了植被和气候类型。我们表明，土壤碳 (C) 含量与全球生物群落土壤中的微生物多样性-生物量关系和比率相关。这个比率提供了一个综合指数来识别地球上那些多样性比生物量高得多的位置，反之亦然。土壤微生物多样性与生物量的比率在低碳含量的干旱环境中达到峰值，而在富含碳的寒冷环境中非常低。我们的研究进一步表明，与土地利用集约化和气候变化相关的土壤碳含量减少可能导致微生物多样性-生物量比率发生巨大变化，并对广泛的土壤过程产生潜在影响。