The Anthropocene is defined by human‐driven environmental change, with one consequence being the modern dramatic decline in biodiversity globally. This is especially worrisome given the long‐acknowledged causal linkage between biodiversity and ecosystem functioning and the delivery of ecosystem services. However, the exact mechanisms driving biodiversity–ecosystem function (BEF) relationships remain unclear, specifically the linkages between species differences, measured by trait and phylogenetic distances, and how interactions, such as competitive inequality and stable coexistence via niche partitioning, influence these relationships. Using complementary plant biodiversity experiments, a synthetic‐assembled one that combined species in different phylogenetic distance treatments with a semi‐natural functional group removal experiment, we assessed how species differences influence the mechanisms underpinning BEF relationships. We calculated the net biodiversity effect (ΔY) of biomass production and partitioned it into two additive parts: the complementarity and selection effects at species and functional group level to test how phylogenetic diversity and functional diversity capture the influences of the complementarity and selection effects. For both experiments, we found that phylogenetic and functional diversity explained biodiversity effects through similar mechanisms, with a positive relationship with the complementarity effect, and a negative relationship with the selection effect. However, we found that the selection effect was best predicted by a negative relationship with functional dispersion (FD_is) of height where the selection effect was strongest in plots with similarly tall species and weakest with a greater diversity of heights, while higher complementary effects were best explained by increasing phylogenetic diversity (i.e. high MPD_a). Our work revealed that the mechanisms underpinning biodiversity–ecosystem function relationships are dependent on species differences and how these differences influence competitive inequalities and niche differences.

中文翻译：

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功能和系统发育多样性解释了多样性对生物量生产的不同影响

人类世的定义是人类驱动的环境变化，其结果是全球生物多样性急剧下降。鉴于长期以来公认的生物多样性与生态系统功能和生态系统服务提供之间的因果联系，这尤其令人担忧。但是，尚不清楚驱动生物多样性与生态系统功能（BEF）关系的确切机制，特别是物种差异之间的联系（通过性状和系统发育距离来衡量）以及相互作用（例如竞争性不平等和通过生态位分配的稳定共存）如何影响这些关系。利用互补的植物生物多样性实验，通过合成组装将不同系统发生距离处理中的物种与半天然官能团去除实验结合在一起，我们评估了物种差异如何影响支撑BEF关系的机制。我们计算了生物量生产的净生物多样性效应（ΔY）并将其分为两个相加部分：物种和功能组水平上的互补和选择效应，以测试系统发育多样性和功能多样性如何捕获互补和选择效应的影响。对于这两个实验，我们发现系统发育和功能多样性通过相似的机制解释了生物多样性的影响，与互补效应呈正相关，与选择效应呈负相关。然而，我们发现选择效果最好通过与功能分散（FD_是）的高度，在具有类似高种的地块中选择效果最强而在高度差异更大的情况下选择效果最弱，而更高的互补效应最好通过增加系统发育多样性（即高MPD _a）来解释。我们的工作表明，支撑生物多样性与生态系统功能关系的机制取决于物种差异以及这些差异如何影响竞争性不平等和生态位差异。