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 fromincrement cores and disks taken at breast height. We examine and compare the estimated parameters forthese models across a range of sample sites. Models are rated on consistency of parameters and on theirability to fit growth data from four sites that are located across a longitudinal gradient across the states ofDelaware, Pennsylvania, West Virginia, and Ohio in the USA. We then examine the differences among thesemodels in their abilities to predict short-term (decade) and longer-term growth of trees. Accuracy andpotential effects of bias are discussed relative to the age and source locations of sample trees used in thisstudy.