Methods For Determining Equilibrium Curve Of Uneven-Aged Theropencedrymion

Uneven-aged theropencedrymion is the most and best way for natural forest, the research of its equilibrium state providing a new way for the sustainable management of natural forest. In this paper, we compared 3 equilibrium models for the uneven-aged selection theropencedrymion with 8 times-collected observed data at 30 sample plots in Jingouling Forest Farm of Jilin Province. Meanwhile we determined the structure stability of actual stand diameter distribution with variances, the Gini and deviation coefficient. Then we 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; Lopez’s equilibrium curve fitted well if the harvest was not considered or the harvest rate equal in each diameter class; Schutz’s equilibrium curve had the best performance to describe the real situation of forest, in which the growth, not only harvest but also mortality information were considered. Compared with the Gini and deviation coefficient, because of being more steadily and sensitively to discover the changes of stand structure, the variance was used for comparing the 3 equilibrium curves. The results showed that:de Liocourt’s equilibrium curve was not sensitive to judge the stability of the stand structure; Lopez’s equilibrium curve was quite harsh and Schutz’s equilibrium curve was in the middle of the two curves for judging the stability. After regulating the expected diameter distribution with the three equilibrium curves, the predicted diameter distribution tended to be stable in the next period.