We are using the hybrid process-based model, 3-PG, to understand the production ecology of loblolly pine (Pinus taeda) plantations under current and future climate conditions. Existing fertilization x throughfall research installations were utilized to validate the model predictions of leaf area index, water use and productivity at four distinct locations of this species range. We employed a comprehensive dataset of climate projections to predict the magnitude of changes in productivity and water use at those sites. Results showed that the model could accurately predict productivity and reasonably accurate predictions of water use and leaf area index. Future simulations indicated that colder sites would show a greater increase in productivity and water use compared to warmer sites, as a result of increasing of carbon dioxide concentration [CO2] and average temperature. Water use was predicted to be driven by leaf area index development, regardless of the climate differences between the four sites.