Is "Sampling Effect" a Problem for Experiments Investigating Biodiversity-Ecosystem Function Relationships?
Is "Sampling Effect" a Problem for Experiments Investigating Biodiversity-Ecosystem Function Relationships?
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DOI：
10.2307/3546757
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发表时间：
1999-11
期刊：
影响因子：
3.4
通讯作者：
D. Wardle
中科院分区：
文献类型：
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作者：
D. Wardle
这些旨在研究生物多样性与生态系统功能之间关系的研究越来越多地利用各种物种多样性的实验设计，从预先确定的物种库中随机确定每个多样性水平的物种组成。利用这种设计的研究受到了批评，因为它们被抽样效应（SE）或选择概率效应所混淆，即具有最高多样性的处理有更大的可能性被整个物种库中最具生产力的物种所主导;然而，也有人声称SE是一种合法的机制，多样性效应可以在自然界中表达出来。首先，我显示，使用一个例子，最近发表的一项研究声称显示多样性效应，如何SE可以导致在识别多样性和生态系统属性之间的明显关系，在真实的世界中没有什么意义。然后，我指出，如果我们接受SE是一个多样性机制在自然界中运作，它首先是必要的假设，生物群落随机组装的生态系统属性正在测量，这种假设是不符合传统的概念，生物群落是如何组织的。最后，我讨论了其他的实验方法，可能会删除的生物多样性研究的结果混淆与SE相关的问题的可能性。SE可能有助于观察到的结果的那些研究都没有成功地显示出不能归因于人为因素的结果，并且需要替代实验方法以更好地理解生物多样性丧失如何影响自然生态系统。
Increasingly, those studies which are aiming to study the relationship between biodiversity and ecosystem function are utilising experimental designs in which species diversity is varied, with the species composition at each level of diversity being determined randomly from a predetermined species pool. Studies utilising such designs have been criticised on the basis that they are confounded by sampling effect (SE) or selection probability effect, i.e. that the treatments which have the highest diversity have a greater probability of being dominated by the most productive species of the entire species pool; however it has also been claimed that SE is a legitimate mechanism by which diversity effects may express themselves in nature. Firstly I show, using an example of a recently published study claiming to show a diversity effect, how SE can result in the identification of apparent relationships between diversity and ecosystem properties which have little meaning in the real world. I then point out that if we accept SE is a diversity mechanism operating in nature, it is firstly necessary to assume that biological communities are randomly assembled with regard to the ecosystem property being measured; this assumption is inconsistent with conventional concepts about how biological communities are organised. Finally I discuss other experimental approaches which may remove the likelihood of results of biodiversity studies from being confounded by problems associated with SE. None of those studies in which SE may contribute to the observed outcome have successfully shown a result which cannot be ascribed to artifact, and alternative experimental approaches are required in order to better understand how biodiversity loss affects ecosystems in nature.