The diversity of primary producers strongly affects the structure and diversity of species assemblages at other trophic levels. However, limited knowledge exists of how plant diversity effects at small spatial scales propagate to consumer communities at larger spatial scales. We assessed arthropod community β and γ-diversity in response to experimentally manipulated plant community richness in two long-term grassland biodiversity experiments (Jena, Germany and Cedar Creek, US) replicated over two years. We calculated arthropod species turnover among all plot combinations (β-diversity), and accumulated number of arthropod species occurring on (1) all pairwise plot combinations, and (2) 40 randomly selected six-plot combinations (γ-diversity). The components of arthropod diversity were tested against two measures of plant diversity, namely average plant α-diversity (P̅S̅R̅) and the average difference in plant α-diversity between plots (ΔPSR). Whereas P̅S̅R̅ points to the overall importance of plant α-diversity for arthropod community turnover and diversity on a larger scale, ΔPSR represents the role of habitat heterogeneity. We demonstrate that arthropod γ- diversity is supported by high, homogeneous plant α-diversity, despite lower arthropod β-diversity among high- compared to low-diversity plant communities. We also show that, in six-plot combinations, average plant α-diversity has a positive influence on arthropod γ-diversity only when homogeneity in plant α-diversity is also high. Varying heterogeneity in six-plot combinations showed that combinations consisting solely of plots with an intermediate level of plant α-diversity support a higher number of arthropod species compared to combinations that contain a mix of high- and low-diversity plots. In fact, equal levels of arthropod diversity were found for six-plot combinations with only intermediate or high plant α-diversity, due to saturating benefits of local and larger-scale plant diversity for higher trophic levels. Our results, alongside those of recent observational studies, strongly suggest that maintaining high α-diversity in plant communities is important for conserving multiple components of arthropod diversity. As arthropods carry out a range of essential ecosystem functions, such as pollination and natural pest-control, our findings provide crucial insight for effective planning of human-dominated landscapes to maximise both ecological and economic benefits in grassland systems.

中文翻译：

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植物多样性对草地无脊椎动物β-和γ-多样性的影响对比

初级生产者的多样性强烈影响其他营养级物种组合的结构和多样性。然而，关于植物多样性在小空间尺度上如何传播到更大空间尺度上的消费者社区的知识有限。我们评估了节肢动物群落 β 和 γ 多样性，以响应在两年内重复的两个长期草地生物多样性实验（德国耶拿和美国雪松溪）中实验操纵的植物群落丰富度。我们计算了所有地块组合中节肢动物物种的周转率（β-多样性），以及在（1）所有成对地块组合和（2）40 个随机选择的六地块组合（γ-多样性）上出现的节肢动物物种的累积数量。节肢动物多样性的组成部分根据植物多样性的两种措施进行了测试，即平均植物 α 多样性 (P̅S̅R̅) 和地块之间植物 α 多样性的平均差异 (ΔPSR)。P̅S̅R̅ 指出植物α多样性对节肢动物群落更新和更大规模多样性的整体重要性，而ΔPSR代表栖息地异质性的作用。我们证明，尽管与低多样性植物群落相比，高多样性植物群落中的节肢动物 β 多样性较低，但节肢动物 γ 多样性得到了高同质植物 α 多样性的支持。我们还表明，在六块地块组合中，仅当植物 α 多样性的同质性也很高时，平均植物 α 多样性才对节肢动物 γ 多样性产生积极影响。六块地块组合中不同的异质性表明，与包含高多样性和低多样性地块的组合相比，仅由具有中等植物 α 多样性水平的地块组成的组合支持更多数量的节肢动物物种。事实上，由于局部和更大规模植物多样性对较高营养水平的饱和益处，在只有中等或高度植物 α 多样性的六块地块组合中发现了相同水平的节肢动物多样性。我们的结果以及最近的观察性研究的结果强烈表明，在植物群落中保持高 α 多样性对于保护节肢动物多样性的多个组成部分很重要。由于节肢动物具有一系列重要的生态系统功能，例如授粉和自然害虫防治，