Abstract: Treeline is one of the most obvious terrestrial ecosystem boundaries. Previous researches showed that treeline was sensitive to climatic change in the 20^th century. In this paper, the concept and characteristics of treeline were first discussed. Then research advances in responses of treeline to climatic change were reviewed. Since the 20th century, the response of treeline to climatic change has exhibited as climbing along altitude, increased forest density in treeline zone, lowering downhill along altitude, and nonchange. Among the four forms, the climbing along altitude accounted for 65% of the summarized studies and they were located in the Scandinavian Mountains, the Pyrenees, and the Polar Ural Mountains. The increased density accounted for 20% of the summarized studies, which were identified in the Scandinavian Mountains and the Polar Ural Mountains. The lowering downhill and non-change accounted for 15% of the summarized studies. Lastly, the reasons causing the treeline change and the future research trends were discussed.

Key words: land use change, soil water holding capacity, soil water conservation, Hainan Island.