18 



BULLETIN 154, IT. S. DEPARTMENT OF AGRICULTURE. 





possible exception of larch. Lodgepole seedlings from 5 to 7 years 

 old with leaders 36 inches long have been noted. In one case a young 

 tree, about 8 years old, had made a height growth of 1\ feet in the 

 last 3 years. Another young tree of about the same age had a 45-inch 

 leader. 



Table 4. — Average height growth of lodgepole pine seedlings on the Deerlodge 

 National Forest, Mont., and the Arapaho National Forest, Colo. 





Height. 



Age in years. 



Height. 



Age in years. 



Deerlodge 

 National 

 Forest. 



Arapaho 



National 



Forest. 



Deerlodge 

 National 

 Forest. 



Arapaho 

 National 

 Forest. 



1 



Feet. 



Feet. 



0.1 



.2 



.4 



.9 



5 



Feet. 

 0.8 



1.0 



Feet. 



1.4 



2 





6 



1.9 



3 



0.4 

 .6 



10 



4.5 



4 



15 



7.9 





1 





The growth figures so far given all apply to unthinned stands. If 

 it were possible to make thinnings when needed that would favor 

 the best trees, the growth of the latter would undoubtedly equal, or 

 even considerably exceed, that shown for the dominant trees shown 

 in Table 2. Such intensive management, however, could be under- 

 taken only in a few favored localities where the market is unusually 

 good. Lodgepole pine stands have been thinned in the past only in 

 the course of ordinary lumbering, which has usually left the smaller, 

 poorly developed trees, many of which could take no advantage of 

 the operation. That even trees of this character often respond to 

 such haphazard thinning with a remarkable increase in rate of 

 growth has already been stated. Out of 91 average trees measured 

 on the Deerlodge Forest, representing those which remained when 

 the surrounding stand was cut, 54 trees, or 59 per cent of the total 

 number, showed a marked increase in growth, while the remainder, 

 or 41 per cent, showed no increase. Differences in rate of growth 

 before and after cutting are shown in Table 5. 



Table 5. — Effect of thinning; average diameter grcnvth of lodgepole pine trees 

 left after cutting, Deerlodge National Forest, Mont. 



Paet I. [Based on 91 trees, irrespective of whether they showed increased growth or not.] 



Diameter 

 breast 

 high. 



Trees. 



Periodic annual diam- 

 eter growth for 20 

 years. 



Time required to grow 

 1 inch in diameter. 



Before 

 thinning, 



After 



thinning 



Before 

 thinning. 



After 

 thinning. 



Inches. 

 3 

 4 

 5 

 6 

 7 

 8 

 9 

 10 



Number. 

 8 

 10 

 15 

 17 

 17 

 15 

 6 

 3 



Inch. 

 0.028 

 .031 

 .037 

 .051 

 .047 

 .059 

 .050 

 .058 



Inch. 

 0.034 

 .042 

 .039 

 .041 

 .057 

 .064 

 .046 

 .054 



years. 

 36 

 32 

 27 

 20 

 21 

 17 

 20 

 17 



Years. 

 29 

 24 

 25 

 24 

 18 

 15 

 21 

 18 



