RCDlob: A Growth and Yield Model for Loblolly Pine that Incorporates Root-Collar Diameter at Time-of-Planting

An individual tree model for loblolly pine (Pinus taeda L.) was developed to predict the response resulting from varying root-collar diameter (RCD) at time of planting. Data for this model were obtained from four plantations in the Lower Atlantic Coastal Plain of the United States. The study involved two levels of silvicultural intensity (1- standard; 2- intensive) and two bareroot seedling ideotypes (1 – standard; 2 – morphologically improved). Measurements were made up to age 12 years. The output from RCDlob was compared to two existing loblolly pine growth and yield model programs. Based on these analyses, a model system was developed that resulted in reasonable estimates of stand development for planting densities ranging from 988 to 1730 trees per hectare and stand ages up to 25 years. This model has been incorporated into a downloadable Windows-based Visual Basic program.