<b>Beyond the SLOSS Debate: Maximum Patch Area as a Driver of Multi-Taxa β Diversity in Fragmented Landscapes</b>

<b>Abstract</b><i>Context</i> Understanding how landscape structure influences β diversity across taxa is central to biodiversity conservation in fragmented ecosystems.<i>Objectives</i> We aimed to disentangle how key features of landscape structure shape multi-taxon β diversity and its turnover and nestedness components. Specifically, we tested whether these effects are consistent across taxa with contrasting dispersal abilities and whether dispersal traits modulate the relative contributions of turnover and nestedness to overall β diversity.<i>Methods</i> Using a multi-taxon framework, we quantified the effects of maximum patch area and maximum isolation on β diversity patterns of woody plants, insects, spiders, and birds inhabiting land-bridge islands in the Thousand Island Lake region, eastern China.<i>Results</i> We found that maximum patch area was the dominant predictor of β diversity in mobile taxa, whereas woody plants responded more strongly to maximum isolation. Within taxa, high-dispersal groups showed stronger area–diversity relationships and higher turnover contributions, while low-dispersal groups showed greater nestedness. Small patches disproportionately contributed to turnover, while larger patches promoted nested assemblages, particularly within mobile taxa.<i>Conclusions</i> These findings challenge the traditional SLOSS (Single Large or Several Small) framework by revealing that large patches maintain regional biodiversity through nestedness-driven processes, while small patches contribute disproportionately to turnover, particularly for mobile taxa. Trait-informed, multi-scale conservation strategies are needed to preserve biodiversity and ecosystem function in increasingly fragmented landscapes.