160 



Forestry Quarterly 



Evidently, each cutting area has as many age classes as there 

 are periods of return in the rotation. The age of the trees on 

 any lot differs by the number of years in the period. 



The cut of the coming winter would then take from this forest 

 (leaving out thinnings) the 10 acres of 120-year-old trees in lot 

 No. 1. That these trees are not in nature separated on a tract 

 of 10 acres is self-evident, but that there should be about 10 acres 

 of such ripe trees is part of the conditions of a regulated selection 

 forest. 



In the above case the 10 acres of ripe material would make 

 10X60 M. ft. or 600 M. ft. B. M. Using Hundeshagen-Von 

 Mantel formula here would give us: Y;. = 60 M. ft.; average 



G„ = Xr=30M. ft. 



Cut = — = 

 r 



2G 2X30 M.X1200 



= 600 M. ft. which are taken by 



120 



cutting over lot No. 1. 



In practice the cut in the selection forest takes the ripe and 

 the poor, it thins, and is to assist reproduction. 



It may and may not take all merchantable material. If cord- 

 wood is merchantable and all merchantable material were to be 

 cut it would mean clear cutting and not selection. What the cut 

 may take and what it should leave is more a question of silviculture 

 than of regulation. It, first of all, must leave a growing stock, 

 large enough in volume and right in age classes, to assure proper 

 growth. (The fact that poor market, etc., may prevent good 

 forestry has nothing to do with these discussions.) 



