BALSAM FIE. 



39 



the age of 70 years the annual growth of balsam fir declines, while that 

 of spruce shows a gradual increase. After the age of 150 years spruce 

 catches up with balsam fir, and finally surpasses it both in height and 

 diameter. On the whole the rate of growth of balsam fir is more 

 rapid durmg its entire life than that of spruce. The growth of 

 spruce is, however, more persistent, and does not exhaust itself as 

 early. It is this persistent growth and its long life which enable 

 spruce to reach larger dimensions. 



This difference in growth is also apparent on cut-over land. Meas- 

 urements in New Hampshire during 10 years following cutting gave 

 the results shown in Table 18. 



Table 18. — Comparative groivth in diameter of spruce and balsam on culled land in 



Grafton County, N. H. 



Diameter breast high at time 

 of cutting (inches). 



Diameter breast 

 high after 10 

 years (inches). 



Diameter breast high at time 

 of cutting (inches). 



Diameter breast 

 high after 10 

 years (inches). 





Spruce. 



Balsam. 



Spruce. 



Balsam. 



8 . . 



8.82 

 10.00 

 11.00 

 12.00 

 13.00 

 14.00 



9.56 

 10.60 

 11.40 

 12.34 

 13.34 

 14.34 



14 



14.64 

 15.64 

 16.64 

 17.64 

 18.64 





9 



15 





10 



16... 





11. 



17 





12. 



18 





13 











Balsam fir up to 13 inches in diameter responded to increased light 

 and space more vigorously than spruce, but did not go beyond the 

 limit of 14 inches, while spruce continued to show a slower but a uni- 

 form increase in growth of 1 inch for each 1 inch in diameter up to 18 

 inches. 



VOLUME GROWTH. 



Tables 19 to 23 give the increment of balsam fir in cubic feet and 

 board measure for the three different types in New York and in cubic 

 feet for all types in Maine. The tables of volume growth, more than 

 the tables of height and diameter growth, bring out the better devel- 

 opment of balsam fir in Maine than in New York and other States. 

 The annual increment in Maine is practically twice that in New York. 

 Similarly, the volume-growth tables bring out more clearly the differ- 

 ences in the increment of balsam fir in different situations. Thus, in 

 the swamp the increment is less than in the flat or on the hardwood 

 slope but is more persistent, illustrated by the fact that at the age of 

 150 years it still continues at an increasing rate. In the swamp the 

 growth of balsam fir resembles more nearly that of spruce. On the 

 hardwood slope the volume growth of balsam fir shows the same tend- 

 ency as that in height and diameter. It reaches its climax compara- 

 tively early and is greatest between the ages of 80 and 95 years. After 



