Ill lllll Mill ■■■■■ ■■■■■ 
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 
15 
20 
4 6 8 10 12 14 
TREE DIAMETER BREAST HIGH-INCHES 
Fig. 4.— Relation of crown width to diameter of tree. (Shortleaf pine, 11 to 60 years 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. 2 
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, 
i Determined in January, 1913, from measurements taken in November and December, 1912. 
2 By L. S. Murphy, Forest Service. 
