Periodical Literature 263 



Otherwise, if the mature stands are deficient and other stands 



too young have to be used in eking out a budget, there is no 



necessity of determining a rotation, during which the forest is to 



be cut over. Then, only the regeneration period of the mature 



stands is to be determined, and budget regulation for the whole 



can be deferred until the younger stands are advanced enough to 



make a systematic cutting over possible, when a mere ageclass 



table may suffice to determine sufficiently closely the rotation 



by trial. 



If F is the total area, fj, J2, J3 the areas of different ageclasses, 



then an assumed cutting over period r determines the cutting over 



periods (or ageclass rotations) of the different ageclasses {cj, q, 



F f. /, rf 



Cj, . . . ) by the relation ~= - = — , or in general, c = -^. Then 



r Cj c^ F 



if Gj, az, aj, . . . are the average ages of the ageclasses, 



beginning with the oldest, the average felling ages will be 



Oj-\-j', a2-\-j-{-Cj; aj+y+Q+Cii etc. And, when the whole is 



cut over the ages «f the new ageclass series will be 



ai=j+C2+<:j+ . . . ; 02 = ^+^3+ . . . ; aj= j+ . . . ; etc. 



By comparing the probable felling age of the stands with the new 

 ageclasses, a judgment can be had as to the desirable r or cutting- 

 over period. 



This is made clear by the following example, asstmiing a 100- 

 acre stand with three ageclasses of 80, 60 and 11 years average, 

 and trying three rotations of 60, 80, 100 years. 



Agedass Average Final 



Rotation (c) Felling Age {a) Ageclass Age 



Areas Age Under Assumed Rotation 



60 80 100 60 80 100 60 80 100 



20 80 12 16 20 86 88 90 54 72 90 



40 60 24 32 40 84 92 100 36 48 60 



40 11 24 32 40 59 75 91 12 16 20 



This shows that for a rotation of 60 years the felling ages 

 are only partially acceptable. The third class would have to be 

 cut at 59 years, and after the forest is cut over, the oldest 

 ageclass would only average 54 years. The relations are better 

 for 80 and best for 100 years, so that 90 to 100 years would 

 be the most acceptable rotation for the whole forest, although, if 



