Growth Models For Slash Pine Families

Height, DBH, and volume growth models in response to density, age, site index, interfamily competition, and genetics were developed for 29 15/16-year-old slash pine families in six progeny tests in Florida. Families significantly influenced the shape, asymptote, and rate parameters of height-age and site index curves. Separate base-age invariant height-age models were developed for each family to account for polymorphism associated with the shape and rate parameters. In Nelder design tests, tree height was not affected by density, but DBH and stand volume-index were negatively related to density as early as age four years. Growth dynamics, based on density, age, site index, competition level, and families, were fit to these data. There were significant differences for the estimated parameters of the equations: -0.0739 to 0.0616 (equivalent to 13% of average total height), -0.0513 to 0.1385 (20% of average DBH) and -0.1598 to 0.3331 (54% of average volume-index) for the poorest to best growing families. Interfamily competition coefficients ranged from -0.0026 to 0.0169 (2% of average height), 0.0206 to 0.0169 (10% of average DBH) and 0.0394 to 0.3758 (42% of average volume-index), and differences between mixed and pure plantings were not significant.

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Author(s): Donald L. Rockwood, B. Yang, H. H. Gresham

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 1995