Diameter structural distribution of spruce-fir mixed forest in Changbai Mountain
[Objective] This study aimed to choose models for simulating diameter structure of harvested spruce-fir mixed forest in Changbai Mountain.[Method] Based on analysis of 12 spruce-fir permanent plots in over-cutting forest that had been cut two or three times,negative exponential model,three parameters Weibull model and finite mixed Weibull model were used for fitting diameter distributions of spruce-fir mixed forest.[Result] The density of tree number was 535-1 035 trees/hm2,and the mean DBH was 20.1-23.9 cm.The skewness was positive in all plots.The negative exponential model was suitable for diameter distribution of plots 1 and 7,three parameters Weibull model was suitable for plots 2 and 4,while finite mixed Weibull model was good for the rest.[Conclusion]The inverse J-shaped curves can be better fitted by negative exponential model,while the irregular distributions can be fitted better by finite mixed Weibull model.