10 



BULLETIN 1061, U. S. DEPARTMENT OF AGRICULTURE. 



of trees per acre (tree density) and the rate of growth of the trees 

 in the stand. The number of longleaf trees per acre for well-stocked 

 stands does not seem to be widely variable at any given age for the 

 different classes of situations, and those shown in Table 1 represent 

 for the various ages about the average for all classes of land. The 

 numbers of trees shown for successive ages indicate how tree popula- 

 tion gradually decreases, because the more vigorous ones crowd out the 

 others which are unable to keep up in the competition for light and 

 root space. 



GROWTH ON CUT-OVER LAND. 



Trees of longleaf pine left in logging on the better classes of soils 

 usually show an accelerated rate of growth, sometimes to a very 



Average Diameter [At4£Ft):.5.0 in 6.9in__jB.3rn 9.3 in I 0.0m 10.4m. 



' ' Height 34ft.._..._.48ft......58ft .64ft. .68 fk..._70f+. 



Volume (Ft. B.Mj_ , 1 .25 .40 70. ... 80 



' ' ' Yield per AcrefFt B.M.) 1,500. .6,000 ......10,500 ..14,500. ...18.000 



Fig. 3. — Growth and yield of longleaf pine on medium soil. 



marked extent. On thin, poor, poorly drained soils, and on very 

 deep, dry, sandy soils an absence of stimulated growth following- 

 logging has generally been reported. 



In central Louisiana (Winn and La Salle Parishes) accelerated 

 growth in diameters as high as 200 to 300 per cent has been found. 

 Trees, for example, that measured 10 inches in diameter at the time 

 of logging and had grown only 1.6 inches during the preceding 10 

 years, at the end of 10 years after logging had increased 3 inches in 

 diameter. This represents an actual increase in timber volume of 

 about 200 per cent, or a final volume of three times the former size — 

 a rate which held generally true for trees up to 15 inches in diameter, 

 but fell off considerably for larger trees. With the increase both in 

 size and stumpage value in the 10 years the value of the 15-inch tree 

 went from 23 cents to 72 cents, while the 10-inch tree increased its 

 former value six times. 



