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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 Ralph L. Amateis and Harold E. Burkhart Department of Forest Resources and Environmental Conservation, Virginia Tech
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?
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
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
Removing ½ of Live Crown Length Age 6 Age 9
Analysis ANOVA methods with comparisons of treatment means versus the control mean (Dunnett’s test)
Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune
Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune
Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune
Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune Prune
Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune Prune
Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune Prune
Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune Prune Prune
Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune Prune Prune
Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune
Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune
Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune
Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune Prune
Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune Prune
Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune Prune
Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune Prune Prune
Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune Prune Prune
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.
Another question regarding pruning: • Is it feasible to prune some of the trees in a loblolly pine stand?
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
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
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
Adj. P-values for Height Growth: Treatment Plots vs Control Plot Prune
Adj. P-values for Dbh Growth: Treatment Plots vs Control Plot Prune
Adj. P-values for Height Growth: Plots Where Some of the Trees are Pruned vs Control Plot
Adj. P-values for Dbh Growth: Plots Where Some of the Trees are Pruned vs Control Plot
After 10 years: • Height: No impact on height development • Dbh: Only heavily pruned trees with unpruned neighbors exhibit reduced Dbh growth
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.