Pruning higher than 17 feet was harder and more expensive. It 

 took only 3. 3 minutes to prune a 6-inch tree to 17 feet, as compared to 

 5. 5 minutes to prune to 23 feet. 



As the trees are cut, a special study will be made to determine 

 if the increased return from pruned trees will repay the investment in 

 pruning. Thinning studies will be started in these plantations in 1955. 



Thinning Slash Pine Plantations 



There is considerable evidence that much damage to slash pine 

 plantations is caused indirectly by heavy thinnings or wildfires that 

 leave the stands open. As a rule, fully stocked slash stands have good 

 resistance to both ice damage and fusiform rust. 



The only unburned slash plantation on the Johnson Tract has 

 been placed under study to determine if planted slash will produce satis- 

 factory yields of pulpwood, poles, pilings, and sawlogs in central 

 Louisiana. The plantation is 8 acres in size and was planted in 1934-35 

 at the rate of 1, 150 trees per acre (a spacing of 6. 25 by 6. 25 feet). Be- 

 cause the stand has never been depleted by fire or cutting, it is still 

 relatively dense and will be kept this way by light thinnings at 3-year 

 intervals . 



It was first thinned in 1948, when 5. 7 cords per acre were re- 

 moved from a total stand of 14.4 cords. The 1951 ice storm destroyed 

 1. 8 cords that were not salvaged. The second thinning, in 1952, took 

 out 3. 4 cords per acre from a total volume of 20. 2 cords. Total growth 

 has so far been 25. 9 cords per acre in 18 years, an average of 1. 4 

 cords per acre each year. This plantation has suffered insignificant 

 damage from the series of severe ice storms that heavily damaged 

 nearby slash plantations that had been opened up by wildfires. 



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