24 BULLETIN 1061, TJ. S. DEPARTMENT OF AGRICULTURE. 



Table 11 assumes that well-stocked stands are heavily cupped 

 with one cup to every tree measuring 7, 8, or 9 inches in diameter, 

 one cup on about one-half of the 10-inch trees and two on the re- 

 mainder, and two cups on all trees 11 inches and over. The figures 

 are for the first year's working. At 30 years, for example, the aver- 

 age yield per crop (10,000 cups) is shown to be 53,000 pounds of gum, 

 which makes in turn about 26.5 barrels of spirits of turpentine 4 and 

 88 barrels of rosin. This is obtained from 210 cups per acre, each 

 yielding 5.3 pounds of gum during the season. This number of 

 cups was hung on 210 trees out of a total stand of 355 trees per acre. 

 At 40 years, a yield of 34 barrels of turpentine may be expected. 

 The yield per acre at 30 years was 1,122 pounds of gum, producing 

 about 28 gallons of turpentine and 1.9 barrels of rosin. These yields 



The production of turpentine and rosin has shown 

 a marked downward trend for some 15 years. This 

 is due chiefly to the exhaustion of virgin timber. 

 The very wasteful and destructive methods generally 

 employed with both old timber and second growth 

 have always meant a total production much below 

 what would be possible under a more conservative 

 system. If the rate of decrease continues, within the 

 next decade or so the United States will lose its com- 

 manding position in the world's market and may in 

 time be unable to supply its domestic requirements. 



seem to be very fair in comparison with the average of about 40 

 barrels of spirits per crop yielded by the better class of mature 

 stands under good working in the Gulf region, and an average for 

 all timber of about 20 barrels per crop. The inclusion of small 

 sizes of trees and very close cupping should not be taken as any 

 recommendation for operating such young stands as a general prac- 

 tice. The figures are given as an indication of what might be ex- 

 pected in working thick stands of young timber before thinning or 

 clearing up the land. 



On the Florida National Forest the longleaf pine of all ages and 

 sizes, 10 inches and over in diameter, in a certain contract yielded 

 a virgin working of 96,000 pounds of gum per crop, which gave 48 

 barrels of spirits and 134 barrels of rosin. This was an average yield 



4 By a coincidence this is the same yield as shown by the 1910 United States census 

 for the average crop in Georgia, where much of the production is from second-growth 

 timber. 



