The habitat amount hypothesis (HAH) predicts that species richness in a habitat site increases with the amount of habitat in the ‘local landscape’ defined by an appropriate distance around the site, with no distinct effects of the size of the habitat patch in which the site is located. It has been stated that a consequence of the HAH, if supported, would be that it is unnecessary to consider habitat configuration to predict or manage biodiversity patterns, and that conservation strategies should focus on habitat amount regardless of fragmentation. Here, I assume that the HAH holds and apply the HAH predictions to all habitat sites over entire landscapes that have the same amount of habitat but differ in habitat configuration. By doing so, I show that the HAH actually implies clearly negative effects of habitat fragmentation, and of other spatial configuration changes, on species richness in all or many of the habitat sites in the landscape, and that these habitat configuration effects are distinct from those of habitat amount in the landscape. I further show that, contrary to current interpretations, the HAH is compatible with a steeper slope of the species–area relationship for fragmented than for continuous habitat, and with higher species richness for a single large patch than for several small patches with the same total area (SLOSS). This suggests the need to revise the ways in which the HAH has been interpreted and can be actually tested. The misinterpretation of the HAH has arisen from confounding and overlooking the differences in the spatial scales involved: the individual habitat site at which the HAH gives predictions, the local landscape around an individual site and the landscapes or regions (with multiple habitat sites and different local landscapes) that need to be analysed and managed. The HAH has been erroneously viewed as negating or diminishing the relevance of fragmentation effects, while it actually supports the importance of habitat configuration for biodiversity. I conclude that, even in the cases where the HAH holds, habitat fragmentation and configuration are important for understanding and managing species distributions in the landscape.

中文翻译：

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栖息地数量假说意味着栖息地破碎化对物种丰富度的负面影响

栖息地数量假说（HAH）预测，栖息地中物种的丰富度会随着“局部景观”中栖息地数量的增加而增加，而该“局部景观”由该地点周围的适当距离定义，而栖息地面积的大小并没有明显的影响。网站位于。据指出，如果得到支持，HAH的后果将是，无需考虑栖息地的配置来预测或管理生物多样性模式，并且保护策略应着眼于栖息地的数量，而不管碎片如何。在这里，我假设HAH拥有并应用HAH预测并将其应用于具有相同栖息地数量但栖息地配置不同的整个景观的所有栖息地。通过这样做，我表明HAH实际上暗示着栖息地破碎化的负面影响，以及其他空间配置的变化，会影响景观中所有或许多栖息地的物种丰富度，并且这些栖息地配置的影响与景观中栖息地数量的影响是不同的。我进一步表明，与当前的解释相反，HAH与零散的物种-区域关系比连续的栖息地具有更陡的物种-面积关系，并且单个大斑块的物种丰富度高于几个小斑块且具有相同的总数区域（SLOSS）。这表明需要修改HAH的解释方式并可以对其进行实际测试。对HAH的误解是由于混淆并忽略了所涉及的空间尺度上的差异而引起的：HAH提供预测的各个栖息地，单个站点周围的局部景观以及需要分析和管理的景观或区域（具有多个栖息地和不同的局部景观）。HAH被错误地视为消除或减少了碎片效应的相关性，而实际上却支持了栖息地配置对生物多样性的重要性。我得出的结论是，即使在拥有HAH的情况下，栖息地的破碎和配置对于理解和管理景观中的物种分布也很重要。它实际上支持栖息地配置对生物多样性的重要性。我得出的结论是，即使在拥有HAH的情况下，栖息地的破碎和配置对于理解和管理景观中的物种分布也很重要。它实际上支持栖息地配置对生物多样性的重要性。我得出的结论是，即使在拥有HAH的情况下，栖息地的破碎和配置对于理解和管理景观中的物种分布也很重要。