An iterative state-space growth and yield modeling approach for unthinned loblolly pine plantations

A mathematical iteration-based projection approach is applied in developing a management-oriented tree growth model for unthinned loblolly pine (Pinus taeda L.) plantations according to the biomass balances among the physical compartments of a tree. In this study, the biomass of each tree compartment is used as a state variable. Tree growth is characterized as a dynamic system in which both inputs and outputs are functions of time. This dynamic system can be updated from one state to another by updating state variables, which is based on a hypothesis from tree physiology that suggests the biomass productivity of a tree is proportional to the foliage biomass. The dynamic processes of the system are described using a transition function and an output function of state variables. This approach evaluates the individual growth response to external forces by predicting some coefficients that regulate the growth response based on the input and output of the system. Compared with the traditional empirical growth and yield modeling approach, this method is more easily adjusted to model growth patterns of plantations managed under different growth conditions. (C) 2001 Elsevier Science B.V. All rights reserved.