Abstract:According to the principle that contents of water and heat are the two main factors for determining the geographical distributions of tree species, moisture-therm indices have been developed with drougt index and growing degree days, for the 8 species (Pinus koraiensis, Fraxinus mandshurica, Tilia amurensis, Qurcus mongolica, Acer mono, Ulmus japonica, Betula platyphylla, and Populus davidiana) in the Korean pine/deciduous mixed forests. By assuming that tree growth under optimum conditions is proportional to its leaf biomass and is inversely proportional to its size, the optimum growth model has been derived for the 8 species. With combination of the index and growth model,the optimum growth processes of trees grown under different conditions of moisture and heat has been simulated, and the growth features of different species and the same species under different moisture and heat conditions have been revealed. These results can be used for classifing quality of geographical distributions of tree species and evaluating a stand growth.