How species coexist despite competing for the same resources that are in limited supply is central to our understanding of the controls on biodiversity^1,2. Resource partitioning may facilitate coexistence, as co-occurring species use different sources of the same limiting resource^3,4. In plant communities, however, direct evidence for partitioning of the commonly limiting nutrient, phosphorus (P), has remained scarce due to the challenges of quantifying P acquisition from its different chemical forms present in soil⁵. To address this, we used ³³P to directly trace P uptake from DNA, orthophosphate and calcium phosphate into monocultures and mixed communities of plants growing in grassland soil. We show that co-occurring plants acquire P from these important organic and mineral sources in different proportions, and that differences in P source use are consistent with the species’ root adaptations for P acquisition. Furthermore, the net benefit arising from niche plasticity (the gain in P uptake for a species in a mixed community compared to monoculture) correlates with species abundance in the wild, suggesting that niche plasticity for P is a driver of community structure. This evidence for P resource partitioning and niche plasticity may explain the high levels of biodiversity frequently found in P-limited ecosystems worldwide^6,7.

尽管竞争争夺数量有限的相同资源，物种如何共存是我们对生物多样性控制^1,2理解的关键。资源共存可能促进共存，因为共生物种使用同一限制资源^3,4的不同来源。然而，在植物群落中，由于量化从土壤^5中存在的不同化学形式获取的磷的挑战，因此缺乏通常限制营养素磷（P）分配的直接证据。为了解决这个问题，我们使用了³³P可以直接将DNA，正磷酸盐和磷酸钙中P的吸收情况追踪到草原土壤中单一培养物和植物的混合群落中。我们表明，共生植物从这些重要的有机和矿物质源中以不同比例获取磷，磷源用途的差异与该物种对磷的根部适应一致。此外，生态位可塑性的净收益（与单一栽培相比，混合群落中物种对磷的吸收增加）与野生物种的丰富度相关，这表明磷的生态位可塑性是群落结构的驱动力。磷资源分配和生态位可塑性的这一证据可能解释了在全球范围内磷限制的生态系统中经常发现的高生物多样性水平^6,7。