Climate change is predicted to alter the composition and structure of the forests of the United States over the coming century with projected increases in temperatures of between 2 and 8°C and associated changes in soil moisture. These environmental changes will likely affect various aspects of tree recruitment, including germination, growth and mortality. To examine the effects of warming on these sensitive stages of development, we are conducting air and soil warming experiments in two eastern deciduous forest sites; one at the Harvard Forest in central Massachusetts, and the other at the Duke Forest in the piedmont region of central North Carolina. At each site, we planted seeds of select tree species near their northern or southern range limits in temperature controlled, open-top chambers. The experimental chambers span two light regimes (closed forest canopy and gap conditions), three temperature regimes (ambient, 3°C, 5°C) and three moisture regimes (upslope, midslope, downslope). By measuring germination, growth and survival, we hope to discern how warming will affect changes in species distribution, phenology and length of growing season, and light and temperature interactions within and amongst species.