Effect of Time-Since-Fire on Ant Communities in a Semi-Arid Landscape

Semi-arid mallee landscapes are shaped by wildfires. Due to climate change, wildfires are expected to become more frequent and intense, making their management a conservation priority. Ants are often used as bioindicators in land management studies, as their composition, richness, and abundance respond to disturbances, including wildfires, both directly and indirectly through habitat modification. In the semi-arid zone of western New South Wales, Australia, we examined how time-since-fire influences ant species richness, abundance, and community composition and assessed whether fire-induced changes in vegetation composition explain the observed patterns in ant community structure. We sampled ants at five sites that last burned 3, 5, 9, 26, and 34 years ago, respectively. We identified 59 ant species from 20 genera in a total of 16,360 sampled ants. We found that post-fire ant communities exhibited higher abundance immediately after fire, while species richness increased with time-since-fire. Early successional stages with greater shrub density favored dominant and opportunistic ant species, whereas later stages with increased tree and grass cover supported more diverse ant communities. These results demonstrate that fire drives successional specialization in ant communities through niche filtering. Maintaining heterogeneous fire-age vegetation mosaics is therefore critical for conserving landscape-level biodiversity in fire-regulated mallee ecosystems.