Linking ecosystem modification by the yellow meadow ant (Lasius flavus) to microbial assemblages in different soil environments

The mound building ant Lasius flavus can sustain many large colonies in extensively managed grassland ecosystems. L. flavus employs specialised nesting strategies in various soil environments, with distinctive mounds possibly constructed to obtain optimal environmental conditions regardless of nest location. As such, L. flavus is an important ecosystem engineer, and by modifying the environment they may affect other organisms. Ten replicate L. flavus nests were chosen from grasslands on soils from different parent material (limestone, peat, sandstone and shale) and compared to similar, nearby ant-free soil. Ecosystem modification was assessed by characterising soil physico-chemical properties and measuring the diversity of general bacteria, general fungi and nitrogen-fixing bacteria. For all soil types L. flavus significantly altered physico-chemical properties. This may be associated with greater microbial activities and highly different microbial assemblages within nests compared to reference soils. Overall, pH and moisture content significantly explained differences in assemblages of bacteria, fungi and nitrogen-fixing bacteria between the nest and reference soils. It remains unclear whether L. flavus directly or indirectly influenced soil microbial assemblages. Forming unique micro-habitats within grassland ecosystems, L. flavus mounds may contribute to the diversity of these ecosystems and understanding processes involved within these micro-habitats is paramount for their conservation.

► Regardless of environment L. flavus had altered major soil properties in nests.
► Nests and ant-free soil had distinct bacterial, fungal and functional assemblages.
► pH and moisture correlated significantly to differences in microbial assemblages.
► Soil microbial diversity can be directly and indirectly influenced by L. flavus.