Analysis of Nonlinear Mixed Effects Model Parameter Estimation Methods Application of Mixed Effects Models in Forest Growth Model Multilevel Nonlinear Mixed-effects Basal Area Models for Individual Trees of Quercus mongolica Effects of diameter at breast height on crown characteristics of Chinese Fir under different canopy density conditions Study of the Dominant Height for Chinese Fir Plantation Using Two-Level Nonlinear Mixed Effects Model Analysis of the Basal Area for Chinese Fir Plantation Using Two Kinds of Nonlinear Mixed Effects Model(Two Levels) Simulation of the branch biomass for Chinese fir plantation using the linear mixed effects model. Individual Crown Diameter Prediction for Cunninghamia lanceolata Forests Based on Mixed Effects Models