Experimental field studies are needed to understand the consequences of global climatic change for local community structure and associated ecosystem processes. We are using 5-m diameter open-top environmental chambers and 1m pvc minichambers to simultaneously manipulate air and soil temperatures at the Harvard Forest and at the Duke Forest in North Carolina. These field manipulations are designed to reveal the effects of temperature increases on the populations, communities, and associated ecosystem services of assemblages of ground-foraging ants. Ants are a model taxon for studying effects of global climatic change because they comprise the dominant fraction of animal biomass in many terrestrial communities and because they provide essential ecosystem services, including soil turnover, decomposition, and seed dispersal. The experiment is designed to test three predictions: 1. Projected atmospheric warming will lead to declines in ant species’ abundances at the warmer, southern extent of their ranges in the US. Conversely, projected atmospheric warming will lead to increases in abundance or range extensions of ant species at the cooler, northern extent of their ranges in the US. 2. Warming will change the relative abundance and composition of ant communities, and will lead to the loss of ant biodiversity. 3. Warming will potentially diminish ecosystem processes and services provided by ants, particularly with respect to the dispersal of seeds. To explore these, we are conducting two experiments. In one experiment, twelve open-top chambers at each site which will each be exposed air temperatures ranging from 1.5 to 7 deg C above ambient; soil temperatures will be increased simultaneously from 0 to ~ 2 deg C. After an initial year of pre-intervention measurements, the experiment will run for 3 consecutive years of continuous warming. In the second experiment, shade cloth and plastic greenhouse sheeting will be used to increase or decrease temperature by 0.5 deg C in sixty minichambers. The minichamber experiment was conducted in 2009 and will continue into 2010. The response variables measured in both experiments include ant activity, population densities and colony sizes of focal species, ant community diversity and species composition, and rates of seed dispersal and predation as mediated by ants.