Species-specific effects of belowground-nesting ants on soil N2O emissions in a tropical forest

Abstract

Most studies on the contribution of ants to N2O emissions focus on above-ground species. However, it is uncertain how belowground-nesting ants affect such gaseous N emissions. Here, we tested the species-specific effects on N2O emissions in a tropical forest, of three ant species, namely Pheidole capellini (a honeydew harvester), Odontoponera transversa (a predator), and Pheidologeton affinis (a scavenger). We observed an approximately three-to six-fold increase in N2O emissions from nests compared to reference soils. Soil temperature and water increased in ant nests and via regression models explained 54–70% and 78–90% of the emissions respectively. N2O emissions were closely associated with mediated effects of ants on carbon and nitrogen pools. The emissions from predatory O. transversa nests were about twice as high as from the nests of honeydew-harvester P. capellini and saprophagous P. affinis. We postulate that these variations in N2O emissions among ant species are due to the different extents of modification of soil variables in tropical forest by them.