270 



COLLECTION OF STATISTICS. 



as the yield capacity depends on the species, sylvicultural 

 system and rotation. 



Assuming, that the yield tables for Scotch pine, given in 

 Appendix III., apply to the woods in question, and that the 

 latter are worked under a rotation of 80 years, the normal 

 mean production j^er acre and year will be as follows : — 

 For the I. Quality class = 146 cubic feet, 

 n. ,. ,, = 90 



III. ,. .. = 87 



The mean annual increment, or the yield cai^acity, of tlie 

 area shown in the above table would therefore be — 

 Yield cai)acity = 



3() X 146 + IK) X !)0 + 65 X 87 = 18,101 cubic feet, 



18,101 , . , 



or average yield capacitv per acre = ,7,-^ = 83 cubic feet. 



