Data from: Food webs obscure the strength of plant diversity effects on primary productivity

Plant diversity experiments generally find that increased diversity causes increased productivity; however, primary productivity is typically measured in the presence of a diverse food web, including pathogens, mutualists and herbivores. If food web impacts on productivity vary with plant diversity, as predicted by both theoretical and empirical studies, estimates of the effect of plant diversity on productivity may be biased. We experimentally removed arthropods, foliar fungi and soil fungi from the longest-running plant diversity experiment. We found that fungi and arthropods removed a constant, large proportion of biomass leading to a greater reduction of total biomass in high diversity plots. As a result, the effect of diversity on measured plant productivity was much higher in the absence of fungi and arthropods. Thus, diversity increases productivity more than reported in previous studies that did not control for the effects of heterotrophic consumption.植物多样性实验通常均发现，物种多样性提升可促进生产力提高；然而，初级生产力（primary productivity）的常规测定多是在包含病原菌、互惠共生生物与植食动物的复杂食物网背景下开展的。正如理论与实证研究的预测，若食物网对生产力的影响随植物多样性水平发生变化，则植物多样性对生产力影响的评估结果可能存在偏差。本研究在迄今运行时长最长的植物多样性实验样地中，通过实验手段移除了节肢动物、叶生真菌与土壤真菌。研究发现，真菌与节肢动物会恒定移除大量生物量，进而使得高多样性样地的总生物量降幅更大。因此，在去除真菌与节肢动物的样地中，多样性对实测植物生产力的提升效应显著高于既往研究结果。由此可见，相较于未控制异养消费（heterotrophic consumption）影响的相关研究，植物多样性对生产力的实际提升效应更强。