Niche differentiation and plasticity in soil phosphorus acquisition among co-occurring plants

First author: Gareth K. Phoenix; Affiliations: University of Sheffield (谢菲尔德大学): Sheffield, UK

Corresponding author: Gareth K. Phoenix

How species coexist despite competing for the same resources that are in limited supply is central to our understanding of the controls on biodiversity. Resource partitioning may facilitate coexistence, as co-occurring species use different sources of the same limiting resource. 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 soil. 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.

物种如何在竞争同一种有限的资源时是如何共存的，对于这一问题的理解有助于我们掌握如何控制生物多样性。资源分配（resource partitioning）可能促进物种共存，正如不同共存的物种对于同一种需求资源采取不同的来源获取方式。然而，在植物群落中，对于常见的限制性营养元素磷的资源分配缺少直接的证据，这是因为我们很难量化植物从土壤中获取的不同化学形态的P。为了对该问题进行研究，作者利用了同位素³³P来直接追踪草原土壤上生长的单一群落和混合群落从DNA、正磷酸盐和磷酸钙中吸收的P。作者发现共生的植物物种从这些重要的有机和矿物质来源获取的P的比例不同，并且P来源使用的差异与其对应植物物种根组织对于P获取的适应能力相一致。此外，在野外条件下，生态位可塑性的净收益，即混合群落中某物种的磷吸收相比于单一群落时的增益，与物种的丰富程度相关，说明了生态位对于P的可塑性是群落结构的驱动因素。本文所提供的P资源分配证据以及生态位可塑性可能解释了为何全球范围上磷受限生态系统中经常会发现生物多样性水平比较高。

p.s. 资源分配（resource partitioning）最开始的定义是物种响应于种间竞争的演化压力而产生的一种演化适应。而近来，“资源分配”这一概念逐渐指某一特定的生态位下，不同的物种在资源使用上面的差异，而不管导致这种差异的源头（参考Walter, G. H. What is resource partitioning? J Theor Biol. 1991, 150(2): 137-143）。

通讯：Gareth K. Phoenix (https://www.sheffield.ac.uk/aps/staff-and-students/acadstaff/phoenix)

研究方向：植物与环境的互作。

doi: https://doi.org/10.1038/s41477-020-0624-4

Journal: Nature Plants

Published date: March 23, 2020