Feeding-strategy effect of Pheidole ants on microbial carbon and physicochemical properties in tropical forest soils

Abstract

The research about the effect of ants on soils is generally focused on the aboveground-nesting ant species in temperate soils. Little is known about the potential of belowground nesting ants in regulating soil properties in tropical forests. In this study, three belowground-nesting Pheidole ant species with different feeding habits were surveyed to explore the nesting effects on microbial carbon and physicochemical properties in tropical forest soils. We found that Pheidole ants with high-density nests can induce a pronounced effect on the concentration and vertical variability of microbial carbon and physicochemical properties in soils. Pheidole capellini as a honeydew harvester elevated the levels of soil microbial carbon, soil temperature, total organic carbon, readily oxidizable carbon, and total nitrogen and NO3−, but decreased soil bulk density. Whereas, the highest increase in soil moisture and NH4+ was observed in the nests of P. noda ants (seed predator), and the greatest decrease of dissolved organic nitrogen was in the nests of P. spathifera ants (scavenger). Pheidole capellini ants inputted more materials into the nests, thus they had the greatest modification on the concentration and vertical change in soil properties. We conclude that Pheidole ant species differ in the direction and power of their effect on soil heterogeneity and soil fertility, which may be mainly attributed to different feeding strategies in the tropical forests.