Methods for determining equilibrium curve of uneven-aged selection theropencedrymion—Taking sample plot data in Jingouling Forest Farm as a case

We compared three equilibrium models for the uneven-aged selection theropencedrymion with eight times of collected observed data at 30 sample plots in Jingouling Forest Farm of Jilin Province. Firstly we determined the structural stability of actual stand diameter distribution with variances, and then optimally restructured existing diameter distribution by non-linear programming model, and finally predicted the diameter distribution in the next period by dynamical matrix model. The result showed that: De Liocourt's equilibrium curve was an ideal diameter distribution; López’s equilibrium curve fitted well if the harvest was not considered or the harvest rate equaled in each diameter class; Schütz’s equilibrium curve had the best performance to describe the real situation of forest, in which not only harvest but also mortality information were considered. After optimally restructuring the actual diameter distribution with the three equilibrium curves, the predicted diameter distribution tended to be stable in the next period.