Functional diversity of cover crop mixtures is thought to improve biomass production and weed suppression, two key agroecosystem services in organic systems. To test this hypothesis, we selected eight cover crop species belonging to four functional groups: (i) vining growing large‐seeded legumes (field pea, common vetch), (ii) erect growing small‐seeded legumes (crimson clover, squarrosum clover), (iii) grasses (barley, oats) and (iv) Brassicaceae (radish, black mustard). Nine cover crop mixtures were designed to create a gradient of diversity in terms of number of species and number of functional groups. A control treatment and all monocrops were included in the trial. Regarding cover crop biomass, mixtures outyielded monocrops by an average of 37%. Both functional identity and composition (i.e. trait complementarity) influenced biomass production and weed suppression provided by cover crops. Regression analysis showed that increase in both species diversity and functional diversity in cover crop mixtures improved the provision of agroecosystem services. Results from this study show that complementarity of species functional traits in cover crop mixtures can be used as a strategy to ensure high biomass production and good weed suppression in changing agroecosystems.

中文翻译：

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覆盖作物混合物的功能多样性增强了地中海农业生态系统中的生物量产量和杂草抑制能力

覆盖作物混合物的功能多样性被认为可以改善生物量生产和杂草抑制，这是有机系统中的两个关键农业生态系统服务。为了检验这一假设，我们选择了属于四个功能组的八个覆盖作物物种：（i）种植正在生长的大种子豆科植物（豌豆，普通v子），（ii）种植正在生长的小种子豆科植物（深红三叶草，方型三叶草） ，（iii）草（大麦，燕麦）和（iv）十字花科（萝卜，黑芥末）。设计了九种覆盖作物混合物，以在物种数量和功能基团数量方面创建多样性梯度。对照治疗和所有单季作物都包括在试验中。关于农作物生物量，混合物平均比单季作物高37％。功能特性和组成（即性状互补性）都影响生物量生产和覆盖作物提供的杂草抑制作用。回归分析表明，覆盖作物混合物中物种多样性和功能多样性的增加改善了农业生态系统服务的提供。这项研究的结果表明，覆盖农作物混合物中物种功能性状的互补性可以用作确保改变农业生态系统中高生物量生产和良好抑制杂草的策略。