Abstract: Two 1-ha plots were set up in an old-growth broadleaf-Korean pine mixed forest in Changbai Mountains, Northeast China, and the Weibull function, negative exponential function, and constant ratio q were used to model the diameter distribution. In the two plots, the diameter distribution of the trees all exhibited inverse J-shape, which meant that understory regeneration was relatively good. Both Weibull and negative exponential functions were suitable for modeling the diameter distribution in primary broadleaf-Korean pine mixed forest, but Weibull function could better predict the number of big trees, compared with negative exponential function. The diameter q values of the two plots were small, being 1.74 and 1.45, respectively, which meant that the slope of diameter distribution was quite mild and there were many big trees in the plots. The constant ratio q was better for expressing the diameter-density of broadleaf-Korean pine mixed forest, being possible to be used to describe the diameter distribution of broadleaf-Korean pine mixed forest.

Key words: Methane oxidation, Vertical profile