A functional-structural model for adults of <I>Pinus tabulaeformis</I> based on GreenLab

Abstract

Aims : In functional-structural plant modeling, trees are composed of elements at the organ level and combined physiological processes and morphological structures. When it is applied to adult trees, we must deal with com- plexity of topology and consider ring growth. Our objective was to apply the functional structural model GreenLab to adult Pinus tabulaeformis trees and parameterize and validate the model. Methods : Destructive sampling was done to collect detailed data including structure and biomass measurements from one 18-year and one 41-year P. tabulaeformis. To extend its application in adult tree growth analysis, we used substructure model to simplify tree topology and introduce ring biomass allocation parameter λ to mix Pressler model and common pool model to analyze tree ring growth in different ages and different environments. Direct parameters were attained from the measurement data, and hidden parameters of the model were calibrated using the generalized least squares method. The model was validated by comparing simulation data with observed data and comparing simulation data to data calculated by empirical model. Important findings : Simulations of P. tabulaeformis growth based on the fitted parameters were reasonable. The coefficients of determination of linear regression equations between observations and predictions ranged from 0.84 to 0.98. The coefficient of determination of linear regression equations between GreenLab simulation data and empirical simulation data was 0.95. The results showed that the GreenLab model can be a new tool to simu- late tree biomass at different growth cycles.