THE EFFECTS OF DOMINANT TREE HEIGHT DEFINITION ON LOBLOLLY PINE GROWTH AND YIELD MODEL OUTPUTS IN THE SOUTHEASTERN U.S.

Dominant tree height measurements drive estimations on stand productivity. Thus, an evaluation on 19 different dominant tree height definitions for loblolly pine (Pinus taeda L.) plantations in the Piedmont/Upper Coastal Plain and Lower Coastal Plain regions was conducted. There were significant differences in average dominant height estimations and tree height distributions between the definitions. Sensitivity to mid-rotation thinning treatments depends on definition usage. Minor differences over a 10-year projection using the Plantation Management Research Cooperative (PMRC) 1996 growth and yield model were observed. Definitions that used the tallest trees yielded the highest estimations for site index and, ultimately, yield per acre, while dominant trees selected by the dominant and co-dominant crown classes produced the lowest values. No significant differences in the PMRC 1996 model’s predictability for growth projections were observed between the definitions. The differences in the model’s output resulted in a maximum 1-year difference in economic rotation age decisions.