Response of Ants and Their Seed Removal in Rehabilitation Areas and Forests at El Cerrejón Coal Mine in Colombia

Abstract

Open-pit coal mining causes strong negative impacts on biodiversity because this activity completely removes thick layers of soil. Focusing on ants as functional agents responding to mine site rehabilitation has proven useful in improving restoration practices. This study sought to evaluate the success of the 20-year-old ecological rehabilitation program at El Cerrejón, one of the world's largest open-pit coal mining operation located in a vulnerable dry tropical forest region of Colombia. This study compared ant assemblages in 13 sites classified along a gradient of rehabilitation sites aged 0-14 years, as well as in three forest reference areas. Two sampling methods (pitfall traps and visual search) were conducted during three sampling periods. Seed removal by ants was also quantified at seven of the 13 sites using seed bait from native plants.Eighty-two ant species, belonging to 29 genera, were found. The highest number of ant species were found inside the forests. Ant species richness increased with rehabilitation age of sites, along with higher canopy cover and milder soil temperature. Rehabilitation actions enhancing these ecological factors might, therefore, favor the presence of wild fauna such as ants. The oldest area (14 years) was the most similar to the forests, both in terms of functional ant groups (guilds) and dominant species. Seed movement was highest in the 14-year-old restored area and was similar to that of the forests, suggesting that this ecological function has been partially restored and that the movement of seed dispersal agents across the landscape would be enhanced.

Removal of Nonmyrmecochorous Seeds by Ants: Role of Ants in Cattle Grasslands

“…The G. ulmifolia species was preferred as much, or more than the P. ligularis (positive control) seeds. However, while in the present study, the ants removed 56% of the G. ulmifolia seeds, this species was the less preferred in mining areas undergoing rehabilitation [17] in a subxerophytic area where the ants removed only 5% of its seeds. Instead, in the same experiment, ants preferred larger arillated seeds such as Capparis sp.…”

“…[33]. Their removal by ants was verified in previous studies in disturbed habitats such as pastures [16,34] and mining areas undergoing rehabilitation [17].…”

“…In general, large ants possess a greater carrying capacity in their jaws and can remove seeds greater distances [27,28]. Nevertheless, small ants usually massively recruit workers towards the seeds and then displace them towards the nests [17,29].…”

“…This interaction could affect the local abundance and distribution of myrmecochorus and nonmyrmecochorous species [8][9][10]. In spite of the growing information on the interaction between ants and seeds in neotropical forests [11][12][13][14], few studies document the process in neotropical agroecosystems (but see [15][16][17]). Thus, the role of ants as dispersers of nonmyrmecochorus seeds in pastures is unknown.…”

Contribución de Pheidole fallax y Ectatomma ruidum (Hymenoptera: Formicidae) en la dispersión y germinación de semillas en áreas rehabilitadas de la mina de carbón del Cerrejón, Colombia

“…fallax remueve grandes cantidades de semillas en las áreas donde se encuentra asociada (Wilson, 2003;Zelikova & Breed, 2008;Domínguez-Haydar & Armbrecht, 2011;Lôbo et al, 2011), en esta investigación se destaca que en solo 15 nidos con sus respectivos basureros fueron extraídas 20 349 semillas, lo que demuestra que esta hormiga presenta una dieta con un fuerte componente de semillas o de estructuras accesorias como eleosoma o arilos (Lôbo et al, 2011), es probable que la alta acumulación de semillas en sus nidos obedezca a una estrategia para mantener recurso disponible para su alimentación (Levey & Byrne, 1993;Pizo, 2008).…”