The ecological literature reports little empirical evidence from biodiversity–ecosystem functioning (BEF ) experiments in wetland systems, even though wetlands are widely known for their water filtering capacity. Experiments comparing the effect of plant monocultures and mixtures on water quality to improve pollutant removal efficiency in treatment wetlands share the characteristics of classical BEF experiments, and so could provide insights for wetland management. To add to our understanding of BEF relationships in wetlands, we evaluated plant diversity effects on water purification through a meta‐analysis of freshwater experimental wetlands comparing monocultures to mixtures. We found 28 studies that matched our criteria for BEF analysis, for a total of 561 diversity effects on pollutant removal. Overall, the meta‐analysis shows no significant effect of plant richness on removal of total suspended solids, but a positive effect on chemical oxygen demand and total nitrogen removal, and a marginal effect on phosphorus removal. Thus, the results of this meta‐analysis are consistent with reports of an overall positive biodiversity effect on ecosystem properties. An analysis of moderator variables shows that the experimental context (size of the experimental units, nutrient load, duration of the experiment) does not explain much of the residual variance. For pollutants that benefit from a positive plant richness effects on removal, mixtures do not perform better than the best monoculture. We found no evidence that plant richness effects are due to functional complementarity among species rather than to the presence of particularly efficient species. Complementarity effects may be less prevalent in highly productive, nutrient‐rich wetlands, compared to nutrient‐limited environments such as natural grasslands. Although findings must be confirmed by long‐term field experiments under natural conditions, result from experimental wetland systems may contribute to a better understanding of biodiversity effect on ecosystem functions in wetlands, in addition to guide practices in natural wetland restoration and the use of constructed wetlands for water treatment.

中文翻译：

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植物多样性对湿地水质的影响：基于实验系统的荟萃分析。

尽管湿地因其滤水能力而闻名，但生态文献报道的湿地系统中生物多样性-生态系统功能（BEF）实验的经验证据很少。比较植物单一栽培和混合物对水质的影响以提高处理湿地污染物去除效率的实验具有经典BEF实验的特征，因此可以为湿地管理提供见识。为了加深我们对湿地中BEF关系的理解，我们通过对淡水实验湿地进行了荟萃分析，比较了单一栽培和混合栽培，评估了植物多样性对水净化的影响。我们发现28项研究符合我们的BEF分析标准，总共对污染物去除产生561种多样性影响。总体，荟萃分析显示，植物丰富度对总悬浮固体的去除没有显着影响，但对化学需氧量和总氮去除有积极影响，对磷去除的边际影响很小。因此，这项荟萃分析的结果与关于生物多样性对生态系统特性产生总体积极影响的报告一致。对主持人变量的分析表明，实验环境（实验单位的大小，养分负荷，实验持续时间）不能解释大部分剩余方差。对于受益于植物富集去除效果的污染物，混合物的性能并不比最佳单一栽培更好。我们没有发现任何证据表明植物丰富性的影响是由于物种之间的功能互补而不是由于特别有效的物种的存在。与营养有限的环境（例如天然草地）相比，互补性影响在高产，营养丰富的湿地中可能不那么普遍。尽管必须通过自然条件下的长期野外实验来证实研究结果，但是湿地系统的实验结果可能有助于更好地了解生物多样性对湿地生态系统功能的影响，此外还可以指导自然湿地恢复和人工湿地的使用。用于水处理。