85- 



felled is planted up or sowa each year. The size of the 

 coupes may obviously be as large as can conveniently be 

 re-stocked artificially ; and, unless re-stocking fails, the ideal 

 or normal type of forest may be approached rery closely 

 under this method^ T^he cbst iind '. difficulty of successfully 

 re-stocking. , large areas are- the chief drawbacks to its 

 employment. ' 



Section VII. — The working scheme and the calcij- 



LATION OP THE POSSIBILITY UNDER THE METHOD OP 

 STOREVED rOUBST. 



1. General working scUeme.— In applying this method the 

 number of stems of each age or size-class to be reserved must 

 be decided oq. This number is deduced from the area covered 

 by the crown of the average' tree of eacli size-class and from 

 the rate of growth. The difference in age between each class 

 is, we may assume, equal to the length of the felling rotation ; 

 and the classes must be formed so that fhe trees of one class 

 will attain the dimensions-of the next- higher class during 

 that interval. Or, if preferable, the size-classes may first be 

 decided on, and the length of the felling rotation, based on 

 the rate of growth, may be made to correspond. 



Thus suppose ihat the diameters of the size-classes determined on are : below 

 J,' I' to 1', 1' to 1^', 1^' to 2', and over 2 feet ; that trees of 2 feet diameter have 

 attained their maximum utility; and that the rate of growth is such that in about 

 50 years the trees of the lowest dimension in one diss attain to minimum size for 

 the next higher class. This period of 30 years would, therefore, be taken as the 

 length of the felling rotation. In such a forest the capital, when normally constituted, 

 would consist of four age-classes, each occupying one-fourth the total area. Thus la 

 one acre, containing 43,560 sgu»re feet, each jge-clas9 would covei' one-fourth of this 

 area, or 10,890 square feet. There would be no crops composed of trees over 2 feet in 

 diameter, as in theory these would be exploited as soon as they reached that size :— 



Class I, stems over 2 feet diameter, occupying . , Sil. 



,, II, „ „ 1| to 2 feet diameter, occupying . 10,890 square feet. 



)i li'j ji I, 1 jj 1^ jj >} II • iu,oyu „ ,, 



„ IV, „ „ 4 „lfoot „ „ . 10,890 „ 



„ V. „ „ below 4 „ .... 10,890 „ „ 



Total . 43,560 



In order to ascertain the number oE stems of each cUss, it would be necessary to 

 measure the areas covered by the crowns of the average trees in each class. We w'U 

 assume these areas to be as follows :— - 



Class I 900 square feet. 



„ n . 625 „ ,. 



„ 111 .' 400 ,, „ 



„ IV . . 100 „ „ 



,, 'V (dominant stems) . . . . • 25 „, „ 



