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Impact of Pruning Young Loblolly Pine Trees: Ten-year Growth Results

Impact of Pruning Young Loblolly Pine Trees: Ten-year Growth Results. Ralph L. Amateis and Harold E. Burkhart Department of Forest Resources and Environmental Conservation, Virginia Tech. Purpose: summarize growth results from two pruning studies:.

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Impact of Pruning Young Loblolly Pine Trees: Ten-year Growth Results

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  1. Impact of Pruning Young Loblolly Pine Trees: Ten-year Growth Results Ralph L. Amateis and Harold E. Burkhart Department of Forest Resources and Environmental Conservation, Virginia Tech

  2. Purpose: summarize growth results from two pruning studies: • What is the impact of early pruning on height and dbh growth? • Is it feasible to prune some of the trees in young stands?

  3. FIELD STUDY: what is the impact of pruning on height and dbh growth? • RCB Design: 2 locations, 4 blocks/location and 5 plots/block • Treatment plots with six rows, six trees per row • Sixteen interior measurement trees • 10 ft x 10 ft square spacing • Planted with genetically improved seedlings • Competition control through age 2 • Annual measurements of Dbh, height, and crown dimensions

  4. Early Tree Pruning (ETP) STUDY: How does severe pruning at young ages impact growth? • Control • Prune ½ the crown at 3 yrs • Prune ½ the crown at 6 yrs • Prune ½ the crown at 9 yrs • Prune ½ the crown at 3, 6, 9 yrs

  5. Age 3 Pruning Treatment: ½ live crown length removed

  6. Removing ½ of Live Crown Length Age 6 Age 9

  7. Analysis ANOVA methods with comparisons of treatment means versus the control mean (Dunnett’s test)

  8. Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune

  9. Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune

  10. Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune

  11. Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune Prune

  12. Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune Prune

  13. Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune Prune

  14. Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune Prune Prune

  15. Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune Prune Prune

  16. Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune

  17. Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune

  18. Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune

  19. Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune Prune

  20. Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune Prune

  21. Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune Prune

  22. Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune Prune Prune

  23. Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune Prune Prune

  24. After 10 years: • Height: Only age 3-6-9 lift treatment is shorter than control. • Dbh: Only age 6 lift and the age 3-6-9 lift treatment have smaller Dbh than control.

  25. Another question regarding pruning: • Is it feasible to prune some of the trees in a loblolly pine stand?

  26. FIELD STUDY • RCB Design: 2 locations, 4 blocks/location and 5 plots/block • Treatment plots with eight rows, eight trees/row • Thirty-six interior measurement trees • 6 ft x 6 ft square spacing • Planted with genetically improved seedlings • Competition control through age 2 • Annual measurements of Dbh, height, crown dimensions

  27. Some Tree Pruning (STP) STUDY: Is it feasible to prune some of the trees in a stand? Treatments After Year 6 • Control • Prune 25% of the live crown length on all the trees • Prune 50% of the live crown length on all the trees • Prune 25 % of the live crown length on ½ the trees • Prune 50% of the live crown length on ½ the trees Scheme for systematically pruning ½ the trees on a plot

  28. Control Plot at Age 6

  29. Age 6 Pruning Treatments Remove ¼ crown on all trees Remove 1/2 crown on all trees Remove ¼ crown on every other tree Remove 1/2 crown on every other tree

  30. Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune

  31. Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune

  32. Adj. P-values for Height Growth: Plots Where Some of the Trees are Pruned vs Control Plot

  33. Adj. P-values for Dbh Growth: Plots Where Some of the Trees are Pruned vs Control Plot

  34. After 10 years: • Height: No impact on height development • Dbh: Only heavily pruned trees with unpruned neighbors exhibit reduced Dbh growth

  35. Overall Conclusions • Light pruning affects neither height nor diameter. • Following severe pruning, height growth of pruned trees is little affected even where neighbors remain unpruned; diameter growth is more negatively impacted than height growth. • Pruning some of the trees in a stand does not improve the growth of neighboring unpruned trees. • Growth recovery occurs quickly following pruning. • Pruning treatments employing multiple lifts negatively impacts height and diameter.

  36. Questions?

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