LIFE HISTORY OF SHORTLEAF PINE. 



33 



The storm lasted for nearly a week and many of the bent trees which 

 were given a permanent "set" were alive after 14 years of suppres- 

 sion. The record of interchange of crown classification and resultant 

 growth is well illustrated in the breast-high sections of two repre- 

 sentative trees shown in the illustration. In the 10-year period fol- 

 lowing the storm, the tree suppressed by the ice changed from 97 per 

 cent to 13 per cent rate of diameter growth, while an adjacent and 

 formerly partly suppressed tree showed, as a result of the opening up, 

 an increase of growth from 65 to 122 per cent. 



An immediate response in diameter growth at the age of 58 years 

 is exhibited in Plate VII, showing a representative tree opened up 31 

 years prior by a tornado in Montgomery County, Ark. As a result 

 of this natural thinning the growth averaged 8 rings to the inch for 

 the 30 years following as compared with 16 rings per inch for the 30 

 years preceding the natural thinning. The increase in basal area 



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Fig. 12.— Increased rate of growth of 7 representative shortleaf pine trees on a typical cut-over tract, cut 

 5 years ago. Growth in basal area at breast height , for successive 5- year periods , during the past 30 years. 



was 487 per cent during the latter period. The immediate recovery 

 is shown by the increase during the first season. The tornado made 

 a clean sweep along the center, about one-half mile in width, and a 

 thinning of decreasing degree toward the margin of its path, which 

 was about 14 miles in length. 



The ability of a species to recover from suppression can be ascer- 

 tained by a study of cut-over areas following logging operations. 

 The stimulation in growth of shortleaf pine on a typical cut-over tract, 

 logged to an approximate minimum stump diameter of 14 inches 1 5 

 years prior to the examination, is shown graphically in figure 12, based 

 on Table 13. The increase in basal area during the five years following 

 logging is contrasted with the increases for the five preceding five-year 

 periods. Practically all trees observed showed stimulated growth due 

 to thinning and increased light supply. Trees formerly suppressed, 

 however, grew relatively much faster after the logging. The least gain 



1 Hellbig, Ark., near the Arkansas National Forest, logged in 1907 and examined in 1912. 



