Variation within and among species in a pine arboretum

The primary objective of this study was to obtain estimates of variation patterns in specific taxonomic and growth characteristics, within and among species of pines. Twenty-three species growing in an arboretum on the Eastern Highland Rim near Tullahoma, Tennessee were examined. The species were established in plantations of approximately one acre each, and varied in age from 5 to 17 years. Estimates of variation were desired to assess the dependability of the taxonomic characters and to indicate the amount of improvement attainable in future intra- and interspecific breeding programs. A secondary objective of the study was to determine the species with the best potential for planting in Tennessee. The taxonomic features of needle length, number of needles per fascicle, number and position of resin canals, and percent composition of cortical monoterpenes were analyzed for 23 species. Growth characters investigated included survival, stem height and volume growth. Additionally, wood specific gravity and extractive content were determined for the 17 species having mean diameters in excess of 3 inches. Results of the taxonomic analysis verified the identity of the species and generally confirmed the accepted taxonomic grouping of pines. External morphological features displayed the most variation among species and were thus the most dependable as taxonomic characters. However, internal needle morphology and cortical monoterpenes provide additional characters when external morphological features are not sufficiently distinct, and can be most useful to those seeking to identify juvenile material. Species native to the Southeastern United States excelled in stem height and volume growth. On this basis loblolly, eastern white, and Virginia pine are recommended for timber production in Tennessee. Pond pine grew faster and produced more volume than any species except loblolly, and is highly recommended for further testing.