Ants are hypothesized to function as keystone species by altering the physicochemical properties and microbial communities within soils. Such changes have the potential to influence ecosystem functions, including decomposition, nutrient cycling, and plant productivity. Furthermore, ants are sensitive to climate and recent changes in climate conditions may have unexpected consequences by altering ant distribution or activity within soils. Here, we compared current and historical data to determine potential changes in the abundance or distribution of Formica neorufibarbis, a common alpine ant, on Pennsylvania Mountain (Park County, CO). We then analyzed soil abiotic characteristics near ant nests compared to control environments across the elevational range for this ant species. Ongoing experiments will build upon this work by examining ant effects on plant and soil microbial communities. This work will further elucidate the importance of ants as keystone species and identify potential mechanisms by which ants interact with their community to influence ecosystem function.
Compared to historical surveys, ants have become more abundant at higher elevations on Pennsylvania Mountain. This shift in ant abundance and distribution could reflect changes in resource availability or climate conditions, and mirrors general trends observed for other alpine species. In this study, ant abundance was correlated with higher levels of soil carbon and soil organic matter. At higher elevations, ant abundance was positively correlated with soil nitrogen and negatively correlated with soil phosphorus. These results indicate that changes in ant distribution could have potentially significant effects on soil characteristics that scale to influence ecosystem function. Further studies that trace the effects of ants and ant-conditioned soil on microbial communities and plant growth will be key to understanding the importance of these interactions within alpine ecosystems.