Anthills as habitat islands in a sea of temperate pasture

Ants can shape vegetation as seed dispersers and ecosystem engineers. When anthills are long-lasting, they are known to change soil and vegetation characteristics. However, it is unclear whether plant species traits and species composition vary between ant guilds and between parts of individual anthills. We compared different aspects of soil and vegetation (composition, seedling abundance, and functional traits) between anthills and the surrounding mesophilous pasture in Czechia. This pasture hosts eight ant species, which belong to both seed dispersers and non-dispersers. Where feasible, we divided anthills into centres and margins for the analyses. Anthills (area 90.5–4051.7 cm²; 5–19 plant species) displayed different and more heterogeneous (less similar within anthill plot type) vegetation composition when compared to the surrounding area, with more seedlings and several species restricted to anthills. Further, anthills were more functionally diverse and exhibited several differences in traits, both at the community and intraspecific level. Anthill centres had higher surface temperatures in hot sunny days, higher levels of phosphorus and pH than margins, while margins had higher moisture and carbon content than surrounding vegetation. Further, anthill vegetation differed between ant guilds with more myrmecochorous species found at nests of seed dispersers. Overall heterogeneity in this mesophilous pasture was enhanced by the presence of anthills. Further, the anthills themselves are heterogeneous due to variable sizes, persistence, and differences between their centres and margins on long-lasting anthills. Anthills can thus enhance plant diversity by maintaining disturbed microsites and enhancing the growth of seedlings and less competitive plants.