Diaspore removal by ants does not reflect the same patterns of ant assemblages in mining and rehabilitation areas

Abstract

Mining is responsible for drastic ecosystem changes and rehabilitation is used to promote the return of functions after these impacts. In this scenario, we investigated the responses of ant assemblages and diaspore removal by ants to the transformations caused by mining and rehabilitation predicting that (a) the increase in plant density (a proxy for mining intensity) led to an increase in ant richness, percentage of diaspores removed, and changes in species composition that in turn are correlated with changes in environmental variables; (b) the increase in vegetation structure (a proxy for rehabilitation ages) led to an increase in ant richness, percentage of diaspores removed, and changes in species composition that in turn are correlated with changes in environmental variables. Additionally, we also verified which functional groups were primarily responsible for diaspore removal. We sampled arboreal and epigeic ants, diaspore removal by ants, and environmental variables. We found that ant richness and diaspore removal in mining intensity gradient are positively correlated to plant density. Although vegetation structure is positively correlated with ant richness, we found no changes in diaspore removal in rehabilitation gradient. Epigeic omnivore and epigeic generalist predator ants were the most responsible for diaspore removal. Then, we observed that mining decreases ant richness, altering ant assemblages and their functions, and rehabilitation with exotic plants is ineffective to promote the colonization by the main diaspore-removing ants.