30 



A PRIMER OF FORESTRY. 



FIG. 17. Mimic pure selection forest, showing 

 the mixture of ages. 



The silvicultural system called Pure Selection is ap- 

 plied to forests of this kind. It is used chiefly for 

 protection forests in places where it is desirable to 

 keep the cover always unbroken; elsewhere it is out 



of place. Under this 

 system the annual in- 

 crease of the forest 

 must be found before 

 the yield can be deter- 

 mined. (See p. 15.) 

 Then the fully mature 

 trees are cut in every 

 part of the forest 

 every year. The cost 

 of logging is high, for 

 where single trees are taken here and there, roads or 

 other means of transport must be very numerous and 

 costly in proportion to the amount of the cut. 



LOCALIZED SELECTION. 



Logging under the system just mentioned is so ex- 

 pensive as to prevent its application in the United 

 States, except for woods like cherry and black walnut, 

 which have a special and unusual value. But if, instead 

 of taking the yield from every part of a selection for- 

 est, a comparatively small area is cut over each } T ear, 

 the cost of logging may be very greatly reduced. Such 

 a method is admirably adapted to certain forest regions 

 in the United States, as, for example, to the Adiron- 

 dack Mountains of New York, where the forest is com- 

 posed about equally of coniferous and broadleaf trees. 



