143 



enumeration survey has beea'made, on the standing stock in. 

 the forest. 



The general scheme of working and the method of cal- 

 culation having been explained and the possibility deter- 

 mined, the coadition of the stock as regards its sufficiency 

 or insufficiency, the arrangement of the age-classes and so 

 forth, sliould be discussed. The length of the preparatory 

 period, during which it may be necessary to reconstitute the 

 crop or lead it on to normal condition, should also be 

 explained. 



Example. — It is proposed to exploit the principal speoies, leak, by the selection 

 method ; and the length of the felling rotation adopted is 20 years or half the period 

 (40 years) required for a tree of the lowest diinensions of Class II to attain the lowest 

 dimensiouB of Class I. The enumeiatiou 'surveys show that the age-ciasses are as 

 follows :— 



Class I 65,871 trees. 



„ II 87,ft46 „ 



„ III 33,000 „ 



„ IV 937.000 „ 



It may be assumed that, as there are 87,846 trees of the 2nd Class, the greater 

 propnrtion of which will attain exploitable dimensions in the course of 40 years, the 

 number of trees which will become exploitable each year is something less than 87,846 

 -7-40 or about 2,000 trees. Under a felling rotation of 20 years, the normal exploit- 

 able stock on the ground should therefore be : — 



In the area first felled over 20 years ago 2,000 x 20 



20 

 „ next ,, 19 years ago 2.000 X 19 



20 

 etc., etc., etc., 



„ last ,, 1 year ago 2,000 x 1. 



20 



The normal exploitable stock would, therefore, be 100 x (20 + 19 + &o. -(- 1) — 

 21,000 trees. 



There is therefore an existing surplus stock of 65,871—21,000 or say, 44,000 

 exploitable trees. 



The condition of the crop shows that trees of Class III are markedly deficient 

 and that there will be a dearth of exploitable trees 40 years hence and indeed tbere- 

 after until the present stock in Class IV matures 80 years hence. 



A preparatory period of 80 years is, therefore, necessary in order to properly 

 constitute the stock ; and it is proposed to spread the felling of the surplus stock of 

 44,000 trees over this period (or rather to diminish the fellings of the younger stock 

 propi>rtiouately). The annual fellings should, therefore, be within (44,000-i-8u) + 2,000 

 trees, or about 2,660 trees a year. 



{ii) Period for which the fellings are prescribed. — The 

 time during which the felling operations are prescribed in 

 detail should be explained and justified. In the case of selec- 

 tion fellings the period chosen would be the length of the 

 felling rotation, and the rotation should, therefore, be 

 justified. 



Example, — It is desirable, in order that tbe area worked over each year should 

 not be iuconveuieutly large, that the felling rotation should be a? long as possible 



