Although habitat loss is the predominant factor leading to biodiversity loss in the Anthropocene 1 , 2 , exactly how this loss manifests—and at which scales—remains a central debate 3 – 6 . The ‘passive sampling’ hypothesis suggests that species are lost in proportion to their abundance and distribution in the natural habitat 7 , 8 , whereas the ‘ecosystem decay’ hypothesis suggests that ecological processes change in smaller and more-isolated habitats such that more species are lost than would have been expected simply through loss of habitat alone 9 , 10 . Generalizable tests of these hypotheses have been limited by heterogeneous sampling designs and a narrow focus on estimates of species richness that are strongly dependent on scale. Here we analyse 123 studies of assemblage-level abundances of focal taxa taken from multiple habitat fragments of varying size to evaluate the influence of passive sampling and ecosystem decay on biodiversity loss. We found overall support for the ecosystem decay hypothesis. Across all studies, ecosystems and taxa, biodiversity estimates from smaller habitat fragments—when controlled for sampling effort—contain fewer individuals, fewer species and less-even communities than expected from a sample of larger fragments. However, the diversity loss due to ecosystem decay in some studies (for example, those in which habitat loss took place more than 100 years ago) was less than expected from the overall pattern, as a result of compositional turnover by species that were not originally present in the intact habitats. We conclude that the incorporation of non-passive effects of habitat loss on biodiversity change will improve biodiversity scenarios under future land use, and planning for habitat protection and restoration. Analysis of 123 studies of assemblage-level abundances of focal taxa from fragmented habitats finds that increasing fragmentation has a disproportionately large effect on biodiversity loss, supporting the ecosystem decay hypothesis.

中文翻译：

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生态系统衰退加剧了生物多样性的丧失，栖息地的丧失

尽管栖息地丧失是导致人类世生物多样性丧失的主要因素 1, 2，但这种丧失究竟是如何表现出来的——以及在何种尺度上——仍然是一个核心争论 3 - 6 。“被动抽样”假说表明，物种的消失与其在自然栖息地中的丰度和分布成比例 7 , 8 ，而“生态系统衰退”假说表明生态过程在更小和更孤立的栖息地发生变化，因此更多的物种仅因栖息地丧失而造成的损失比预期的要多 9, 10 . 这些假设的普遍检验受到异质抽样设计的限制，以及对强烈依赖于规模的物种丰富度估计的狭隘关注。在这里，我们分析了来自不同大小的多个栖息地碎片的焦点分类群的组合水平丰度的 123 项研究，以评估被动采样和生态系统衰退对生物多样性丧失的影响。我们发现对生态系统衰减假说的总体支持。在所有研究、生态系统和分类群中，对较小栖息地碎片的生物多样性估计——当对采样工作进行控制时——包含的个体、物种和群落比对较大碎片样本的预期更少。然而，在一些研究中（例如，栖息地丧失发生在 100 多年前的那些研究）由于生态系统衰退导致的多样性损失低于整体模式的预期，这是由于物种的组成更替导致的存在于完整的栖息地。我们得出的结论是，将栖息地丧失对生物多样性变化的非被动影响纳入未来土地利用以及栖息地保护和恢复规划下的生物多样性情景。对来自破碎栖息地的焦点分类群的组合水平丰度的 123 项研究的分析发现，不断增加的破碎化对生物多样性丧失具有不成比例的巨大影响，支持生态系统衰退假说。