Abstract: The vertical distribution of CO₂ gradient in the artificial mixed broad-leaf tree/conifer forest on different climatic conditions (clear, cloudy, rainy) and Larix olgensis Henry physiological characteristic in its pure forest and its mixed with Fraxinus mandshurica Rupr.were determined. Results indicate that the net Larix olgensis Henry Photosynthetic rate is higher in its mixed forest with Fraxinus mandshurica Rupr.than that in the pure stand by 42.5%, and their diurnal patterns show bi-peak.The Larix olgensis Henry chlorophyll content in the mixed forest is higher than that in pure forest by 48.44%.Larix olgensis Henry light compensation point is 1000 Lx, and its light saturation point is 50000Lx. The diurnal processing of transpiration of Larix olgensis Henry in both the mixed forest and the pure forest show monopeak.Larix olgensis Henry transpiration rate is higher in the pure stand than that. in the mixed stand by 2.4%.Larix olgensis Henry transpiration efficiency is 4.0g/kg in the mixed stand, and 2.8g/kg in the pure stand. The contents of organic substance and mineral element of Larix olge-nsis Henry different in different kind forest.The contents of protein, fat, and total sugar of Larix olgensis Henry are respectively higher in the mixed stand than those in pure stand.The quantity of N, Mn in Laric olgensis Henry, P, K, and Mn in Fraxinus rnandshurica Rupr., and N, P, K, Mg, and Zn in soil are respectively higher in the mixed stand than those in pure stand. The P absorption of Larix olgensis Henry is faster and more in mixed forest than that in pure forest.The soil pH and soil temperature in mixed forest are higher than, those in pure forest. From all that above, the results are that mixed forest improved soil nutrient condition, and ecological environment, so improved primary productivity and biomass.

Key words: Larix olgensis Henry, mixed forest, net photosynthetic rate, mid-day depression, light compensation point, light saturation point, H₂O