Opportunist ant species dominate metropolitan microhabitats: Evidence from the eastern margin of the Qinghai-Tibetan plateau

Ongoing urbanization presents substantial threats to biodiversity and ecosystem functions, especially in regions with fragile ecosystems. Measuring these threats requires investigation of taxa that (i) continue to occur even in urbanized areas, and (ii) fulfill a substantial role in ecosystem function. In this study, we evaluated how variation relating to microhabitat factors (vegetation complexity, soil nutrients, and fragmentation) affected assemblages of 55,890 ground-foraging worker ants (81 species; seven functional groups) at 64 urban and suburban sites across eight counties over a broad elevational range of 510-3380 m (a.s.l.) in the eastern margin of the QinghaiTibetan Plateau. We found that the representation of opportunist species (a functional group favoring open habitats) was affected by vegetation composition, habitat fragmentation, and soil mineral content, such that opportunists typically comprised the majority of ant species richness (>= 40 % of ant species in 87.5 % plots). Species richness for these opportunists was greater with simpler ground cover (i.e., a lower percentage of herbaceous cover or lower percentage of bare soil). More complex ground cover, edaphic factors and less habitat fragmentation could therefore be used to promote a greater diversity of other functional groups with broader ecosystem function and service potential. Our study demonstrates that optimizing microhabitat management in urban green spaces could be used to mitigate the negative impacts of urbanization on native ant communities, and to safeguard key ecosystem functionality with a cascade effect to broader biodiversity.