data submission from Resource stoichiometry shapes community invasion resistance via productivity-mediated species identity effects

The diversity–invasion resistance relationships are often variable and sensitive to environmental conditions such as resource availability. Resource stoichiometry, the relative concentration of different elements in the environment, has been shown to have strong effects on the physiology and interactions between different species. Yet, its role for diversity–invasion resistance relationships is still poorly understood. Here, we explored how the ratio of nitrogen and phosphorus affects the productivity and invasion resistance of constructed microbial communities by plant pathogenic bacterium, <i>Ralstonia solanacearum</i>. We found that resource stoichiometry and species identity effects affected the invasion resistance of communities. Both high nitrogen concentration and resident community diversity constrained invasions, and two resident species, in particular, had strong negative effects on the relative density of the invader and the resident community productivity. While resource stoichiometry did not affect the mean productivity of the resident community, it favoured the growth of two species that strongly constrained invasions turning the slope of productivity–invasion resistance relationship more negative. Together our findings suggest that alterations in resource stoichiometry can change the community resistance to invasions by having disproportionate effects on species growth, potentially explaining changes in microbial community composition under eutrophication.群落多样性-入侵抗性关系通常具有变异性，且易受资源可获得性等环境条件的影响。资源化学计量比（resource stoichiometry），即环境中不同元素的相对浓度，已被证实会对物种生理过程及种间互作产生显著影响。然而，其在多样性-入侵抗性关系中所扮演的角色仍未得到充分解析。本研究探讨了氮磷比对人工构建微生物群落的生产力以及植物病原细菌青枯雷尔氏菌（Ralstonia solanacearum）入侵抗性的影响。研究发现，资源化学计量比与物种身份效应均会影响群落的入侵抗性。高氮浓度与本地群落多样性均可抑制入侵，且有两个本地物种对入侵者的相对密度及本地群落生产力表现出极强的抑制作用。尽管资源化学计量比对本地群落的平均生产力无显著影响，但它会促进那两个可强效抑制入侵的本地物种的生长，进而使生产力-入侵抗性关系的斜率变得更负。综上，本研究结果表明，资源化学计量比的改变可通过对物种生长产生差异化影响，进而改变群落的入侵抗性，这或可解释富营养化过程中微生物群落组成的变化。