Abstract: Potted saplings of Pinus koraiensis, Picea koraiensis, Larix olgensis, Populus ussuriensis, Betula platyphylla, Tilia amurensis, Traxinus mandshurica, and Acer mono,the eight dominant species in the Korean pine broadleaf forest at Changbai Mountain,were grown in open top chambers with ambient(400μl·L^-1) and elevated (700μl·L^-1) CO₂ concentration under natural sunlight for two growing seasons.The average height growth of these eight species under elevated CO₂ increased by 10%～40%, compared with the control at ambient CO₂. The response of transpiratory rate to the higher CO₂ concentration was different among the species,and the water use efficiency of the saplings of the 8 species growing under elevated CO₂ concentration was higher than that under ambient CO₂. Soluble sugar and chlorophyll contents were not related to the CO₂ concentration under which the saplings grew, indicating that the complicacy was existed in the acclimation of tree species to high CO₂ concentration. The response of broad leaved tree species to the elevated CO₂ concentration was more sensitive than that of conifer tree species.Saplings of all tree species showed a photosynthetic acclimation to higher CO₂ under long term elevated CO₂ concentration.