Increasing trends in precipitation and temperature related to forest restoration in the southern United States

Land cover changed dramatically in the southern U.S. during the last century. One of the major changes was the forest restoration from farming lands in the first half of the century due to both natural (tree regrowth) and human (plantation) processes. Vegetation is one of the factors controlling land-atmosphere energy and water exchanges. The forest restoration in the southern U.S., therefore, is expected to have led to changes in regional climate. This study examines this issue by conducting simulation and experiments with a regional climate model. The simulation domain is the continental U.S. with a resolution of 60 km. The simulation periods are July and January months of eight years. The results indicate that overall precipitation and temperature increase due to forest restoration. The contributing factors for the precipitation increase include the generation of cyclonic circulation in the atmospheric disturbances and larger water transfer into the atmosphere from the land-surface. The reduced albedo due to forest restoration leads to increased solar radiation absorption and sensible heat flux on the land-surface, which in turn leads to the temperature increase.