LIFE HISTORY OF SHORTLEAF PINE. 



11 



constancy and, so far as is known, 1 has never before been found to 

 exist in any North American tree species. It was found to hold true 

 for all crown classes within a range of ages from 20 to 80 years, rep- 

 resenting average diameters up to about 16 inches. Indications 

 point to this relation holding true beyond 80 years, although no meas- 

 urements in pure shortleaf pine have been made. Later measure- 

 ments by Prof. H. H. Chapman, of Yale Forest School, indicate a 



4 6 8 10 12 14- 16 16 20 



TREE DIAMETER BREAST HIGH-INCHES 

 Fig. 4.— Relation of crown width to diameter of tree. (Shortleaf pine, 11 to 60 3 r ears old, in Arkansas.) 



constant relation between the diameter and crown in mixed short- 

 leaf and loblolly pine stands from 80 up to 200 years; also recent 

 deductions from yield and growth data of red spruce show a definite 

 relation existing between basal area and growing space in even-aged 

 stands between 20 and 100 years. 3 



The evidence from which the conclusion is drawn is shown in figure 

 4, based on 545 trees on 25 sample plots, representing 16 different ages, 



1 Determined in January, 1913, from measurements taken in November and December, 1912. 



2 By L. S. Murphy, Forest Service. 



