The SLOSS debate in fragmented grasslands: A multi-dimensional biodiversity perspective.

Conservationists have long debated whether fragmented habitats are best conserved by protecting a single large patch (SL) or several small patches (SS), i.e., the SLOSS debate. Although this SLOSS debate has provided important insights into biodiversity conservation, research has predominantly focused on only one dimension of diversity (i.e., taxonomic), failing to consider how phylogenetic and functional diversity might inform conservation strategies. In this study, we determined whether grasslands in the agro-pastoral ecotone of the Tabu River Basin, Inner Mongolia should be conserved by protecting a single large patch or several small patches. For this purpose, we quantified the relationships between three dimensions of biodiversity (taxonomic, phylogenetic, and functional diversity) and grassland patch area. We found species richness and the standardized effect size of phylogenetic diversity increased with patch area, whereas the standardized effect size of functional diversity decreased. Taxonomic measures of diversity indicated that the best strategy for conserving Tabu River Basin grasslands is to protect several small habitat patches; in contrast, phylogenetic and functional measures of diversity indicated that conserving a single large habitat patch was best. Our study emphasizes the necessity of considering multiple dimensions of diversity when designing conservation strategies for fragmented landscapes to achieve comprehensive biodiversity conservation.