33^ Forestry Quarterly. 



value increment from the most desired to stouter sizes suddenly 

 falls off and those which like pine, oak, etc., continue into old age 

 to appreciate. If then the rotation based on the most desired size 

 for any reason does not satisfy, the relation of value increment to 

 cost of production ascertained by use of the index per cent, may 

 serve. If the interest rate secured in sinking gradually, the 

 preference is to be given to the forest rent because for State forest 

 the larger income within limits is preferable to the higher interest 

 rate. When, however, an increase in the net forest rent can be 

 secured only with a considerable reduction in interest rate, and an 

 increase in volume and value production cannot be secured by 

 managerial measures (thinnings) then the lengthening of the rota- 

 tion would not be desirable. Besides these calculatory bases, 

 other considerations are to aid in determining the rotation, such 

 as influence of the length of rotation on soil conditions, capacity 

 for natural regeneration, winddanger, decrease of health with 

 growing age, influence of intensive thinning practice, and other 

 managerial considerations. 



The financial question — the fundamental requirement of the soil 

 rent theory — as to the interest rate on the production capital enters 

 then only in the third place, and only when the other two con- 

 siderations, size and value production, do not suffice. But, after 

 all, the rotation of the highest soil rent cannot vary very much 

 from that rotation which produces in the shortest time the largest 

 quantity of the most desired sizes and hence best paid material ; 

 the value increment forms the best index for the financial felling 

 age. The author reproduces the following curves to show in 

 what relation these rotations may stand, the curves are derived 

 from a definite spruce stand on site II in Austria. They show 

 that value increment, quality (size) increment, and soil rent coin- 

 cides in their maximum closely. 



For selection forest and coppice or coppice with standards size 

 alone, d. b. h. is serviceable to determine the felling age, although 

 quality and value increment determinations are not excluded. 



As regards the method of budget regulation the new instruction 

 strikes out in a new direction. While in both the allotment and 

 the normal forest methods the budget is derived from a general 

 working plan with a period table — a tabular exhibit of the fellings 

 in area and volume from period to period bringing to view the 

 progress toward the ideal of the future — now the felling plan is 



