38 BULLETIN 55, U. S. DEPARTMENT OF AGRICULTUBE. 



COMPABATIVE GROWTH OF SPRUCE AND BALSAM FIR. 



Since spruce and balsam fir nearly always grow together, and any 

 plan of management for one species must necessarily include the 

 other, a comparison of the growth of the two species is essential. 



In Table 17 is contrasted the average growth in height and diame- 

 ter of balsam fir and spruce in the State of Maine. 



Table 17. — Comparative growth, in height and diameter, of balsam, fir and red spruce in 



Maine. 



GROWTH IN HEIGHT. 





Height (feet). 



Diameter breast high 

 (inches). 



Height (feet). 



Diameter breast high 

 (inches). 



Red 



spruce. 



(Based on 



485 trees.) 



Balsam 



fir. 



(Based on 



456 trees.) 



Red 



spruce. 



(Based on 



485 trees.) 



Balsam 



fir. 



(Based on 



456 trees.) 



1 .. 



7 12 

 14 20 

 21 27 

 28 35 

 33 42 

 37 48 

 . 41 54 

 44 60 

 48 64 



10 



.52 

 55 



58 

 60 

 63 

 65 

 67 

 68 

 70 



68 



2 



11 



72 



3 



12 





4 



13 



78 



5 



14. . 



81 



C . . .. 



15 



84 





16 



86 



8 



17 





9 ; 



18 















GROWTH IN DIAMETER. 





Diameter breast 

 high (inches). 



Age (yeai's). 



Diameter breast 

 high (inches). 



Age (years). 



Red 



spruce. 



(Based on 



274 trees.) 



Balsam 



fir. 



(Based on 



456 trees.) 



Red 



spruce. 



(Based on 



274 trees.) 



Balsam 



flr. 



(Based on 



456 trees.) 



20 



0.1 

 .6 

 .8 

 1.1 

 1.5 

 1.8 

 2.2 



1.2 

 2.7 

 4.1 

 5.5 

 6.7 

 7.9 

 8.9 



90 



2.7 



9 (} 



30 



100 



3. 2 10. 7 



40 



110 



3. 7 11.3 



50 



120 



4.3 11.9 



60 . . 



130 



4.9 ; 12.3 



70 



140 



5.5 . 12.6 



80 



150 



6.2 12.9 











Red spruce grows in height much slower than balsam fir for the 

 first 70 years. At a diameter of about 8 inches its rate of growth in 

 height is approximately the same as that of balsam fir. At a diame- 

 ter of 12 inches balsam fir reaches almost its full height, while spruce 

 is still far below its fullest development. From that time on spruce 

 continues to grow at a uniform rate for a long period, while the 

 growth of balsam fir is rapidly declining until at a diameter of about 

 16 inches it practically ceases. 



The same is true of the growth in diameter. At the age of 100 

 years spruce is only 3.2 inches in diameter breast high, while balsam 

 fir has made nearly two-thirds of its entire diameter growth. After 



