Linkages between bacteria and nutrient availabilities in slash-and-burn tropical soils vary with feeding-habit ants

As important structuring forces in forest ecosystems, ants can drive above- and belowground food-webs and ecosystem functionality. It remains uncertain, however, about how different foraging-habit ants shape symbiotic bacterial assemblies and nutrient cycling in nest soils. This study quantified the impacts of predatory and honeydew-feeding ants on soil bacterial communities and nutrient pools in Xishuangbanna tropical forests restored from slash-and-burn agriculture. In contrast to reference soils, all ant nests increased the relative abundances of dominant copiotrophs and decreased those of preponderant oligotrophs in the bacterial communities, which was closely associated with the high levels of carbon (C) and nitrogen (N) in the nests. Honeydew-feeding ants harbored a high abundance of bacterial trophic groups (i.e., gamma-Proteobacteria, Firmicutes, and Bacteroidetes) preferring low-quality resource, owing to high increment (103%) in C concentration and low increase (69%) in N level compared to reference soils. In contrast, predatory ants sheltered a high assemblage of bacterial taxa (i.e., beta-Proteobacteria and delta-Proteobacteria) favoring high-quality resource, due to increased N level (135%) and decreased C:N ratio (35%) compared to reference soils. We concluded that the foraging-habit ants shaped symbiotic bacterial assemblages primarily through differential modifications on level and allocation of soil C and N pools. Our results would further the understanding of the fauna roles in driving soil food-webs as well as nutrient cycling.