Soil moisture patterns below mounds of harvester ants

Abstract

Harvester ants are a major component of western rangeland. Little is known about ants' role in soil water dynamics. Annual patterns of soil moisture under mounds of the harvester ant (Pogonomyrmex owyheei, Cole) were studied in southeastern Idaho. Soil moisture at 20-cm intervals to a depth of 100 cm was estimated monthly with a neutron probe. Between 60 and 100 cm, higher levels of moisture were found below mounds than in control areas. The amount of water added to the soil during spring recharge was greater in control areas at 20 cm but greater under ant mounds at depths below 60 cm. Under ant mounds, approximately 1.3 cm more water was added to the soil between 60 and 100 cm.