After the recent rains, many people have noticed the large amount of ant activity in some areas of the bush.
Often people comment about increased ant activity before rain events as a “sign” of rainfall – there isn’t scientific evidence for ants detecting weather events, but it is highly likely that they can respond to environmental cues such as humidity and pressure.
The activity after a rain event is the ants cleaning out their tunnels and shows the role of the ant tunnels activity in the infiltration of water.
Ants can excavate a significant amount of soil from deeper layers and deposit it on the soil surface. Obviously, the more nests in an area, the more soil is being moved around. This can affect the surrounding vegetation. Continuous heaping of soil may support the persistence of some annual plants that would otherwise suffer from competition in dense vegetation. The ant environment may also support species with fast root growth or long rhizomes. In some cases, this mixing of soil can substantially change the environment for plant growth.
Ants concentrate plant and animal material around the nest site, and this rapidly becomes mixed with the excavated soil. Nutrients such as mineral nitrogen tend to remain within a decomposing particle unless it is incorporated in the soil so that this mixing of soil and organic matter by the ants contributes to the release of nutrients. Studies have found consistently higher levels of nitrogen, phosphorus and carbon in ant nest areas.