A survey of arbuscular mycorrhizal fungal root inoculum associated with harvester ant nests (Pogonomyrmex occidentalis) across the western United States.

Soil organisms are known to affect the population dynamics of mycorrhizal fungi in many ecosystems. The western harvester ant, Pogonomyrmex occidentalis, is widespread in its distribution and creates patch disturbances that affect both plant and soil microbial communities. Harvester ant-plant-fungus interactions can result in the formation of dense root mats in nest soils and abundant viable mycorrhizal root inoculum. We surveyed mycorrhizal root inoculum in nests of P. occidentalis across its distributional range to address whether root mats and fungal enrichment were a common consequence of ant activity. We concluded that mycorrhizal root mats were unique to particular plant communities (sagebrush steppe) and were not a common feature of P. occidentalis' nests across its distributional range.