FOREST, FISH AND GAME COMMISSION. 



197 



The following table has been constructed from Table No. 17, and 

 shows the growth in diameter to be expected in trees of 4 to 13 inches, 

 breasthigh, in periods ranging by decades from 10 to 60 years: 



TABLE No. 18.— GROWTH IN DIAMETER OF SPRUCE BY io-YE.-\R PERIODS. 



Present 



diameter 

 breasthigh. 



Inches. 

 4 



5 

 6 



7 

 8 



9 

 10 

 ii 



12 



Diameter 



breasthigh 



after lo years. 



Inches. 



9 00 

 10.13 

 II 27 



12.43 

 13-45 

 14.46 



Diameter 



Diameter 



breasthigh 



breasthigh 



after .to years. 



after 30 years. 



Inches. 



Inches. 





8-73 



8.94 



10.00 



10.13 



11.40 



II 40 



12 86 



12.71 



14 15 



13 89 



15.48 



15.00 



16.66 



16.16 



17.84 



Diameter 



breasthigh 

 after 40 years. 



Inches. 



8-31 

 9.80 



11 .27 



12 86 



14-31 

 15.80 

 17 17 

 18-34 



Diameter 



breasthigh 



after 50 years. 



Inches 



9 



35 



II 



00 



12 



71 



14 



31 



16 



00 



17 



51 



18 



87 







1 



Diameter 



breasthigh 



after 60 years. 



Inches. 

 8.62 



10.50 



12.43 

 14 15 

 16.00 

 17.67 



Knowing from the valuation sun-eys the number of trees per acre of 

 various diameters down to 5 inches, breasthigh, the future stand may be 

 calculated by the use of Table No. 18. For purposes of comparison, the 

 yield which might be obtained in the next iive decades if the present cut 

 were made to a diameter limit of 10, 12, or 14 inches, breasthigh, respec- 

 tively, has been calculated. The following table shows the yields of Spruce 

 which might be obtained after successive lo-year periods on Township 40, 

 expressed in standards, and the number of years which must elapse before 

 an equal cut can be obtained, provided the same diameter limit is adhered 

 to at that time. 



TABLE No. 19.— ESTIMATE OF FUTURE YIELD PER ACRE OF SPRUCE ON MER- 

 CHANTABLE AREA. 



Cutting limit: 



diameter 



breasthigh. 



Average 



present stand 



per acre. 



Average cut per acre obtainable at the 

 to-year periods, in standards. 



end of 



Interval required 



between 



equal cuts. 





Standards. 



10 



20 



30 



40 



50 





Inches. 













Years. 



10 



22.94 



1.90 



5.20 



10.00 



16.10 



24.20 



50 



12 



19-43 



2.20 



6.20 



12.40 



20 70 





39 



14 



15.56 



3.80 



9.20 



16.60 







29 



