Two days ago, a paper was published in Ecosphere that describes a perhaps unexpected relationship between arboreal (tree-dwelling) ants and small detritivorous creatures underfoot. The authors, Clay et al., focus on the Neotropical ant species Azteca trigona. According to the authors, this species “rains refuse out of its hanging nest onto the leaf litter below”. Essentially, A. trigona just throws its poop and trash onto the ground below its nesting tree.
While it may be considered impolite for humans to do such things, the ants’ refuse is enriched with various nutrients (Phosphorous, Potassium, and Nitrogen) that limit decomposition. That is, the detritivores in the soil and leaf litter are limited by a limitation of these nutrients, so that an increase in the abundance of the nutrients would increase the rate of decomposition, and therefore the rate of nutrient cycling, in the ecosystem. Consistent with this fact, Clay et al. found that in the areas below the trees that housed A. trigona nests, the rate of decomposition was increased 1.2-fold (i.e. 20%). So, by throwing to the ground all that junk inside their trunk, ants can actually provide an important ecosystem service.
Clay, N. A., J. Lucas, M. Kaspari, and A. D. Kay. 2013. Manna from heaven: Refuse from an arboreal ant links aboveground and belowground processes in a lowland tropical forest. Ecosphere 4(11):141. http://dx.doi.org/10.1890/ES13-00220.1