Nowhere in the world have tree improvement and silviculture had a bigger impact on forest productivity and value to landowners than in the southern US. The economic impact from almost 60 years of tree improvement in the southern United States has been staggering. For example, over 300,000 hectares are planted each year with seedlings from the breeding efforts with loblolly pine (Pinus taeda) by members and staff of the North Carolina State University Cooperative Tree Improvement Program. The present value of continued genetic gains from traditional tree improvement efforts is estimated to be $2.5 billion USD to landowners and citizens in the southern US.
Wood discs cut from 23-year-old lodgepole pine (Pinuscontorta Dougl. var. lalifolia Engelm.) stems were analyzed for vertical and radial resin duct densities adjacent to basal injuries caused by the weevil, Hylobiuswarreni Wood. The injury from single attacks continued for at least 2 years and was characterized by reduced radial growth and an abundance of vertical 'traumatic' resin ducts above the wounds. No increase in radial duct density was detected above the wounds.
A productivity study and system evaluation was carried out on a tree-length operation working in a second thinning of loblolly pine near Greenville, North Carolina. The average tree volume was 8.1 ft3 and the average dbh was 8.4 in. The machines studied in the system were the Tigercat 720B feller-buncher, the Tigercat 630 skidder, and the tracked loader Tigercat 245. The goal was to reduce the standing timber from 225 trees/ac down to 92. Standard time-study methodology and multivariance statistical analyses were used to capture and evaluate the data. The key productivity parameters identified for the feller-buncher was piece volume and number of trees in the bunch, and for the skidder extraction distance, average piece volume and number of bunches picked up to make a turn. The ability of the loader to process increasing number of trees as average tree volume decreased, and the increased difficulty of delimbing the larger trees resulted in no significant variance for average piece size. Productivity functions were developed for the feller-buncher and the skidder. The system evaluation discusses the productivity balance between the machines for the given range of piece size as well as potential operational improvements based on in-field observations. South. J. Appl. For. 27(2):77–82.
Tip moth damage among families of parent pine species and their interspecific F1 hybrids was quantitatively assessed in a coastal planting in North Carolina. Three slash pine (Pinus elliotti var. elliotti Engelm.), two loblolly pine (Pinus taeda L.), and four interspecific F1 hybrid pine families were used. The F1 hybrids were as susceptible to damage by Nantucket pine tip moth (Rhyacionia frustrana (Comst.)), as was their susceptible loblolly pine parent. Their phenotypes support a dominant or partially dominant mode of inheritance for susceptibility. The phenotype of one slash pine family was not statistically different from the phenotypes of the loblolly and F1 hybrid pines. The high susceptibility of that one slash pine family appeared to be intrinsic, even though slash pine is considered resistant to tip moth damage. Tip moth damage on the two other slash pine families was significantly lower.
Differences in survival, diameter, height (site index), and stem profile among eight North Carolina half-sib families and one Mississippi–Alabama commercial check of loblolly pine (Pinus taeda L.) at three spacings over 17 years were evaluated for effects on a growth-and-yield model. Actual stand volume at age 17 was determined from a 100% measurement of all trees. This volume was compared with predicted volumes from age nine measurements using (i) the unmodified model and (ii) the model after modifications for family differences. Modifications to the model included family-specific site indices for height differences and family-specific regression functions for each of the other traits. The unmodified model resulted in an underestimate of actual stand volume by 31%. Adjustments for family differences in dominant height (site index), survival, or profile had little effect on this bias. Insertion of family-specific regressions for stem profile and site index in combination with survival-diameter density effects greatly reduced the bias and provided the best estimates of future stand volumes.
Direct-seeding of loblolly pine (Pinus taeda L.) in the Piedmont was evaluated using combinations of the following treatments: hand-casting and mechanical broadcast sowing; use of stratified and unstratified seed; and sowing during November, January, and March. Sowing stratified seedin November and unstratified seed in March resulted in the lowest stocking; however, regeneration was accomplished by all treatments. Costs including seed, but exclusive of site preparation costs, were $10/ac for hand-casting and $18/ac for mechanical sowing. Because capitalis the most limiting resource for accomplishing regeneration on nonindustrial private forestland, direct-seeding is a viable regeneration alternative. When adequate labor is available, direct-seeding is an effective alternative to machine use. South J. Appl. For. 13(2):91-93.