Abstract:

Establishing basal area growth model of Phoebe zhennan secondary forest in Hunan province to provide theoretical basis and scientific guidance for its growth prediction and management decision-making.Taking Phoebe zhennan secondary forest in the National Forest Inventory sample of Hunan province from 1989 to 2014 as the object,the basic model of basal area growth was constructed based on 5 theoretical models with biological significance.On this basis,the site index closely related to stand growth is added to construct the site index model.In order to improve the prediction accuracy of the model,the mixed effect model of the growth of Phoebe zhennan secondary forest in Hunan area is constructed by adding the random parameters including stand density.The Logistic growth model with the highest coefficient (R²=0.241 0) and prediction accuracy (P=98.821 3%) and the smallest sum of residual squares (SSE=2 986.149 2) was selected as the basic model;the site index was added to parameter b₁,and the site index model of Hunan Phoebe zhennan secondary forest was constructed,the coefficient of determination was increased to 0.3312.The mixed effect model was constructed by dividing the stand density into different grades,the results showed that the AIC and BIC values of the simulation with random parameters added to parameter b₄ were the lowest,and the fitting effect was significantly better than other simulation (p< 0.000 1);compared with the basic model,the ME,MAE,RME and RMAE values of the mixed effect model were significantly reduced,and the R² was increased to 0.946 2,and the prediction accuracy was improved.The mixed effect model can improve the prediction accuracy of stand area growth,eliminate the differences between different density grades,and provide scientific basis for the reasonable management of Phoebe zhennan secondary forest in Hunan province.

Key words: Phoebe zhennan, basal area, secondary forest, growth, mixed effected model