Comparing basal area growth models, consistency of parameters, and accuracy of prediction

We fit alternative sigmoid growth models to sample tree basal area historical data derived from increment cores and disks taken at breast height. We examine and compare the estimated parameters for these models across a range of sample sites. Models are rated on consistency of parameters and on their ability to fit growth data from four sites that are located across a longitudinal gradient across the states of Delaware, Pennsylvania, West Virginia, and Ohio in the USA. We then examine the differences among these models in their abilities to predict short-term (decade) and longer-term growth of trees. Accuracy and potential effects of bias are discussed relative to the age and source locations of sample trees used in this study.