Abstract
As volume is the primary measure of value in loblolly pine (Pinus taeda L.) stands, knowledge about the stem taper of commonly deployed clones may better describe genetic gains made by each clonal variety and could provide more accurate volume estimates. Clonal varieties with combined low taper and fast growth can potentially offer great gains in uniformity, quality, and volume when deployed operationally. Clones propagated via somatic embryogenesis from 13 full-sib families and two open-pollinated families were measured in the eighth growing season across three sites in coastal Georgia and South Carolina. Three form quotients were used to analyze stem taper differences among clones and to assess taper impacts on total stem volume. Significant clonal variation was found for form quotients, indicating that genetic differences exist in stem taper among different clones. Clone mean heritability estimates for form quotients and growth traits were moderate to high (0.64–0.94), indicating that the use of form quotients could improve selection by accounting for taper in clones. However, taper impacts on total volume were minimal after accounting for dbh and total height, and differences among clones in total volume were sufficiently captured using a single combined-variable D2H equation. While selecting clones by total height and dbh may not necessarily capture clones with the least taper, this method was sufficient for selecting varieties with the largest volumes.
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