Abstract: Two compatible biomass equations of Pinus koraiensis single tree were built using nonlinear simultaneous equations modeling theory, then biomass of each tree organ of every plot was calculated. The forest biomass distribution in tree organs based on forest age, diameter at breast height and forest density was analyzed. Furthermore, the effect of main forest factors on forest biomass was discussed. The results were as follows: Young age P.koraiensis plantation forest biomass are positively correlated with the average diameter at breast height; Forest density has a great effect on forest biomass and the most suitable forest density is 1 000-1 400 N·ha^-1; The distribution law of young and middle-age P.koraiensis plantation forest biomass are the same, stem>root>branch>leaf, biomass of aboveground forest is the main part of stand biomass and accounts for about 79%; The proportion of aboveground and underground biomass is about 3.8∶1.

Key words: biomass, Pinus koraiensis plantation, compatible biomass model, stand density, Mengjiagang forest farm