Abstract Annual actual evapotranspiration (AE) was computed with data from 150 weather stations in and near the natural range of loblolly pine. The main distribution of the species is defined by values of AE between 813 and 1,050 mm. The 737 mm isoline of AE denotes conditions of inadequate energy in the north and insufficient moisture in the west which restrict loblolly pine to a well-defined natural range. Forest Sci. 21:339-340.