Effect of ants on sandy soils in semi-arid eastern Australia - Local distribution of nest entrances and their effect on infiltration of water

The influence of the funnel ant (Aphaenogaster barbigula) on water infiltration was studied on an aeolian soil in a semi-arid Callitris glaucophylla woodland in eastern Australia. At the study site at Yathong Nature Reserve, densities of up to 37 nest entrances m-2 were recorded in some areas, equivalent to a density of 88 000 entrances ha-1 over small areas or 0.9% of the surface area of the landscape. Seventy-two per cent of the entrances were actively being used by the ants. Steady-state water infiltration on soils with entrances averaged 23.3 mm min-1 which was about four times that on entrance-free soils. As the diameter of the nest entrance increased, water penetrated deeper into the soil. The results provide further evidence that ants have a marked influence on redistribution of water in semi-arid environments.