Ant communities are structured by patch and landscape level factors

Landowners and conservation groups are converting marginal agricultural land to semi-natural habitats, such as conservation grasslands. These grasslands are imbedded within a matrix of agriculture, urbanization, and semi-natural habitats and are colonized over time by grassland dependent animals. Ants are widespread arthropods that structure above and belowground food webs and interact with other organisms as predators, herbivores, and mutualists. Ants are also recognized as valuable environmental indicators of disturbance and recovery for management-based monitoring. We studied ant communities in 23 conservation grasslands that differed in area, time since planting, plant community, soils, management, and surrounding landscape. The goals of this study were to differentiate patch and surrounding landscape effects on the grassland ant species composition and diversity. The best model for ant richness was grassland age in 2011 and soil clay content in 2012. Ant community composition was determined by soil texture, surrounding urban land use, and time since burn. Species responded in different ways to patch variables and were also influenced by surrounding landscape. Uncommon habitat specialists were more abundant in high grassland landscapes and patches that were older and larger, while disturbance tolerant species were favored by urbanization and more common in young sites. Our results suggest that ant communities are primarily influenced by habitat age, but soil, management, and surrounding land use have differential effects on individual species frequencies. These findings support a greater use of ants as environmental indicators at the patch and landscape level.