Habitat fragmentation can exacerbate the negative effects of habitat loss for some species. Mitigating fragmentation is difficult, however, because population responses depend on species-level traits (e.g., dispersal ability, edge sensitivity) and landscape context (e.g., habitat amount). Thus, conservation requires determining not only if, but also where and why, fragmentation matters. We aimed to determine if and where grassland fragmentation affects tallgrass prairie birds, which have declined precipitously due to land-use change. We surveyed four edge-sensitive species at 2250 sites (10,291 total surveys) across eastern Kansas, USA, over two breeding seasons. We assessed how the occurrence of each species varied with different levels of fragmentation in local landscapes comprising different grassland amounts. Fragmentation clearly mediated positive relationships between occurrence probability and grassland area for all four species. The direct effect of fragmentation was greater than that of grassland area for two species. Moreover, fragmentation reduced the occurrence of each species by at least half in some contexts. Fragmentation effects were most pronounced in landscapes comprising ~ 50–90% grassland, and less pronounced or absent in landscapes comprising < 50% grassland, which were occupied relatively infrequently. Conservation efforts should minimize ‘perforation’ of large grasslands by woody vegetation and land development, which not only replace grassland, but also often create disproportionately large amounts of grassland edge. Identifying mechanisms responsible for edge effects could further inform species-level conservation. Our results counter assertions that fragmentation does not matter or only matters when habitat is scarce or for species that are dispersal limited.

中文翻译：

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草原破碎化对数量下降的高草草原鸟类的影响最大，但仍有大量草原

栖息地破碎化会加剧某些物种栖息地丧失的负面影响。然而，缓解碎片化是困难的，因为种群响应取决于物种水平的特征（例如，扩散能力、边缘敏感性）和景观背景（例如，栖息地数量）。因此，保护​​不仅需要确定碎片是否重要，还需要确定碎片在何处以及为什么重要。我们旨在确定草原破碎化是否以及在何处影响高草草原鸟类，由于土地利用的变化，这些鸟类急剧减少。在两个繁殖季节，我们在美国堪萨斯州东部的 2250 个地点（总共 10,291 次调查）调查了四种边缘敏感物种。我们评估了在包括不同草地数量的当地景观中，每个物种的出现如何随着不同程度的破碎化而变化。碎片清楚地介导了所有四种物种的发生概率与草地面积之间的正相关关系。两个物种破碎化的直接影响大于草地面积。此外，在某些情况下，碎片化使每个物种的出现率至少减少了一半。碎裂效应在包含约 50-90% 草地的景观中最为明显，而在包含 <50% 草地的景观中不那么明显或不存在，这些草地相对较少被占用。保护工作应尽量减少木本植被和土地开发对大草原的“穿孔”，这不仅取代了草地，而且经常造成不成比例的大量草地边缘。确定负责边缘效应的机制可以进一步为物种级保护提供信息。