Decomposing tree annual volume increments and constructing a system dynamic model of tree growth

We developed a dynamic system growth model of 55-year-old Pinus resinosa trees, compartmentalizing growth based on statistical approaches. Annual volume increment of trees was subdivided into several distinct components, each of which has some unique properties and responds to different factors that influence growth. The formulas for different growth components were estimated by statistical or numerical methods. The software STELLA was used to transfer a conceptual dynamic growth model into a practical computer model. Using STELLA, tree growth can be simulated over time and examined in relation to prevailing environmental events or conditions. The model can aid in evaluation of tree growth response to environmental stimuli and intrinsic factors, and provides a basis to predict future growth. Extrapolation of model results should be limited to conditions under which the model was developed and not to novel environmental change or for older trees.