The species pool concept has advanced our understanding for how biodiversity is coupled at local and regional scales. However, it remains unclear how species pool size - the number of species available to disperse to a site - influences community assembly across spatial scales. We provide one of the first studies that assesses diversity across scales after experimentally assembling grassland communities from species pools of different sizes. We show that species pool size causes scale-dependent effects on diversity in grasslands undergoing restoration by altering the shape of the species-area relationship (SAR). Specifically, larger species pools increased the slope of the SAR, but not the intercept, suggesting that dispersal from a larger pool causes species to be more spatially aggregated. This increased aggregation appears to be caused by sampling effects due to fewer individuals arriving per species, rather than stronger species sorting across variation in soil moisture. These scale-dependent effects suggest that studies evaluating species pools at a single, small scale may underestimate their effects, thereby contributing to uncertainty about the importance of regional processes for community assembly and their consequences for ecological restoration.

中文翻译：

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物种池大小在实验群落组装过程中改变物种-区域关系

物种库概念加深了我们对当地和区域范围内生物多样性如何耦合的理解。然而，目前尚不清楚物种池的大小——可分散到一个地点的物种数量——如何影响空间尺度上的群落组装。我们提供了在实验性地从不同大小的物种库中组装草原群落后评估跨尺度多样性的首批研究之一。我们表明，通过改变物种-面积关系 (SAR) 的形状，物种库的大小会对正在恢复的草原的多样性产生规模依赖性影响。具体来说，较大的物种池增加了 SAR 的斜率，但没有增加截距，这表明从较大池中分散会导致物种在空间上更加聚集。这种增加的聚集似乎是由采样效应引起的，因为每个物种到达的个体较少，而不是在土壤水分变化中更强的物种分类。这些与规模相关的影响表明，在单一、小规模上评估物种库的研究可能会低估它们的影响，从而导致区域过程对群落组装的重要性及其对生态恢复的影响的不确定性。