Consumer versus resource control of producer diversity depends on ecosystem type and producer community structure
Consumer versus resource control of producer diversity depends on ecosystem type and producer community structure
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DOI：
10.1073/pnas.0701918104
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发表时间：
2007-06-26
影响因子：
11.1
通讯作者：
Smith, Jennifer E.
中科院分区：
文献类型：
--
作者：
Hillebrand, Helmut;Gruner, Daniel S.;Smith, Jennifer E.
植物群落多样性的消费者和资源控制长期以来一直被视为替代假设。然而，实验和理论证据表明，食草动物和营养资源相互作用地调节共存植物物种的数量和相对丰度。实验已经产生了不同的，往往是相互矛盾的生态系统内部和之间的反应，并没有任何努力，以协调这种经验的变化在一个一般的框架。利用来自海洋，淡水和陆地生态系统的274个实验的数据，我们提出了一个跨系统的分析生产者多样性响应当地操纵的资源供应和/或草食动物。草食动物和施肥对生产者丰富度的影响在系统之间有很大的不同：（i）草食动物减少了淡水中的物种丰富度，但往往增加陆地系统中的丰富度;（ii）施肥增加了淡水系统中的丰富度，但减少了陆地上的丰富度。施肥持续降低均匀度，而食草动物只在海洋和陆地生态系统中增加均匀度。生产者群落均匀度和生态系统生产力介导施肥和草食动物对生态系统多样性的影响。草食动物增加生产者丰富度更富有成效的栖息地和生产者组合低均匀度。这些相同的组合也表现出最强的减少施肥丰富，而施肥增加（草食动物减少）丰富的生产者组合具有高均匀度。我们的研究表明，系统生产力和生产者均匀度决定的方向和规模的自上而下和自下而上的多样性控制，并可能调和不同的经验结果内和生态系统之间。
Consumer and resource control of diversity in plant communities have long been treated as alternative hypotheses. However, experimental and theoretical evidence suggests that herbivores and nutrient resources interactively regulate the number and relative abundance of coexisting plant species. Experiments have yielded divergent and often contradictory responses within and among ecosystems, and no effort has to date reconciled this empirical variation within a general framework. Using data from 274 experiments from marine, freshwater, and terrestrial ecosystems, we present a cross-system analysis of producer diversity responses to local manipulations of resource supply and/or herbivory. Effects of herbivory and fertilization on producer richness differed substantially between systems: (i) herbivores reduced species richness in freshwater but tended to increase richness in terrestrial systems; (ii) fertilization increased richness in freshwater systems but reduced richness on land. Fertilization consistently reduced evenness, whereas herbivores increased evenness only in marine and terrestrial ecosystems. Producer community evenness and ecosystem productivity mediated fertilization and herbivore effects on diversity across ecosystems. Herbivores increased producer richness in more productive habitats and in producer assemblages with low evenness. These same assemblages also showed the strongest reduction in richness with fertilization, whereas fertilization increased (and herbivory decreased) richness in producer assemblages with high evenness. Our study indicates that system productivity and producer evenness determine the direction and magnitude of top-down and bottom-up control of diversity and may reconcile divergent empirical results within and among ecosystems.