Loblolly pine provenance testing in Tennessee

Six loblolly pine (Pinus taeda L.) provenance test plantations distributed across Tennessee (ages 19 to 26 years from planting) were evaluated on an individual tree basis for total height, dbh, volume and basal area. In addition, wood specific gravity and percentage composition of cortical monoterpenes were evaluated at the Ames Plantation in west Tennessee and the Highland Rim Forestry Field Station near Tullahoma. Significant differences among provenances were found at Ames Plantation, the Highland Rim Forestry Field Station, the Counce plantation in west Tennessee and the Stephen's Switch plantation in the lower elevations of the Cumberland Mountains. At the Stephen's Switch plantation, trees from southeast Tennessee, north Alabama and the North Carolina Piedmont and Coastal Plain produced significantly more volume and basal area on a per hectare basis than trees from the Georgia Piedmont or the South Carolina Coastal Plain. At Ames Plantation, trees from Tishomingo, MS (upper- Coastal Plain), Accomac, VA (eastern shore), Johnston, SC (Piedmont), Chilesburg, VA (Piedmont) and Crossett, AR (upper-Coastal Plain) consistently produced the most volume per hectare, basal area per hectare and tonnes of wood per hectare. Intermediate production was attained by trees from Griffin, GA and Cullman, AL, both of the upper- Coastal Plain region. Low production was associated with provenances that originated near Georgetown, SC (Coastal Plain) and in Gulf Coastal Plain localities. Trees in the Counce plantation varied significantly only in diameter and volume per tree. Trees from the South Carolina Coastal Plain, south Alabama and the North Carolina Coastal Plain were largest in diameter and volume, while those from the Georgia Piedmont, Maryland Coastal Plain and northeast Mississippi were smallest. No significant differences among provenances for unextracted and extracted specific gravity, or extractives were evident at either Ames Plantation or the Highland Rim. However, extractives were produced at the Highland Rim in significantly greater amounts than at Ames. With one exception, a general pattern of decreasing specific gravity from the Atlantic Coastal Plain (.475 to .471), inland into the Piedmont region (.466 to .463) was indicated. Considerable variation was found in cortical monoterpene composition; beta-pinene, myrcene, limonene, and beta-phellandrene showed bimodality, while the alpha-pinene data had normal distribution. Combined data from the Ames and Highland Rim plantations revealed that 12 of 16 possible phenotypes occurred when each tree was classified as being "high" or "low" for each of the 4 monoterpenes showing bimodality. High amounts of limonene and beta-phellandrene occurred in greater percentages in trees of western origins, while high amounts of myrcene were frequently found in eastern trees. Distribution of beta-pinene was patchy and no trend was identified. A trend of increasing percent alpha-pinene content in a southwest to northeast pattern was indicated. It was recommended that trees best suited to west Tennessee growing conditions included those from Virginia, the Carolina Piedmonts and north Mississippi. Loblolly pine plantations on the Highland Rim should consist of trees from Virginia and the Carolina Piedmonts. Trees from southeast Tennessee, north Alabama and the North Carolina Piedmont were recommended for planting in the lower elevations of the Cumberland Mountains. Trees planted at the Friendship Forest (ridge and valley) and Norris (ridge and valley) did not indicate statistically significant differences among provenances. Future measurements of these provenance tests were not recommended.