Ant assemblages (Hymenoptera: Formicidae) in rehabilitated areas of a coal mine in Cesar, Colombia

Open-pit coal mine rehabilitation is essential to mitigate ecosystem degradation and biodiversity loss. Given that ants (Hymenoptera: Formicidae) are excellent bioindicators, we evaluated the response of their communities along a restoration gradient in a tropical dry forest ecosystem. Sampling was conducted in five sites: three areas with different rehabilitation ages (1.5, 4, and 7 years) and two ecosystems not affected by mining (a dry forest fragment and a natural regeneration area). A total of 65 species and morphospecies were recorded, belonging to 30 genera and seven subfamilies. A key finding was the asynchronous recovery of diversity: while species richness (q0) in the sites with longer rehabilitation times resembled that of the reference forest, community structure, measured by evenness (q1, q2), remained significantly lower, indicating a slower functional recovery. Composition analysis (NMDS) revealed a clear successional gradient, with the 7-year site representing an intermediate state in the trajectory toward reference forests. Notably, rehabilitation techniques such as mulch application in the youngest site (1.5 years) promoted the early colonization of specialist predatory ants, resulting in a more complex community than that of the 4-year site. We conclude that proactive rehabilitation, particularly measures focused on soil protection, accelerates the recovery of the ant community structure.