An assessment of pedoturbation by two species of mound-building ants, Camponotus intrepidus (Kirby) and Iridomyrmex purpureus (F. Smith)

Abstract

Details of the size, structure and occurrence of Carnponotus intrepidus nests and the size, composition and source of the mound cover on Iridomyrmex purpureus nests are reported from several areas of eastern New South Wales. Both species are common, and construct large mounds of mixed topsoil and subsoil with surface covers, which appear to protect the mound from rainsplash erosion. Camponotus thatches the mound with charcoal, leaves and twigs; Iridomyrmex covers the mound in granules of inorganic or organic material that are sufficiently large to absorb most raindrop impact energy. This material is collected from the surface and carried 10-15 m to the nest. Rainsplash erosion protection is probably a factor contributing to nest longevity, which may be as much as 100 years for Iridomyrmex. It is concluded that, despite the impressive size of the nests and the selective use of materials, neither species is very significant in terms of soil mixing when compared with the smaller, more common ant Aphaenogaster longiceps.

Neighbor leaf-cutting ants and mound-building termites: Comparative nest micromorphology

“…Both, Gorosito et al (2006) and Cosarinsky (2006) suggested that the compact structure observed in the walls of galleries and nest chambers was necessary to stabilize the walls and to support the high mass of the Camponotus mound. Lining of nest galleries with clay or "glaze" was also reported for Trachymyrmex turrifex and Camponotus intrepidus, respectively, although its function remains elusive (Wheeler, 1907;Cowan et al, 1985). The employment of fecal matter in ant constructions or excavations has not been reported in the literature.…”

“…The mound itself is not inhabited, and it results from the deposition of excavated soil during colony growth that originates from deep horizons. The mound, however, is not only a passive accumulation of excavated soil, since workers import material to reinforce and stabilize the construction, as observed for other ant species (McCook, 1877;Cowan et al, 1985), and also build structures with defined function like ventilation turrets (Jonkman, 1980b).…”

Formicarious Pedons, the Initial Effect of Mound-Building Ants on Soils

“…The surface of the mounds is often covered with a crust or mulch that can consist of sand grains, pebbles, plant fragments, or whatever coarse material is available (Scott, 1951; Mandel and Sorenson, 1982; Cowan et al, 1985). This mulch appears to be for protection from rain‐splash erosion (Cowan et al, 1985), although rain‐splash still can form a crust on the mounds during rainfall events (Mandel and Sorenson, 1982).…”

Effects of ants on sandy soils in semi-arid eastern Australia .2. Relocation of nest entrances and consequences for bioturbation

“…Baxter and Hole 1967;Mandel and Sorenson 1982;Cowan et al 1985;Mitchell 1988;Lobry de Bruyn and Conacher 1990). Ants interact with soil processes by increasing soil porosity and infiltration, altering ped shape and number, reducing bulk density, regulating soil erosion by depositing subsoil on the surface, regulating plant and animal litter and concentrating organic matter around their nests (Hole 1961).…”