304 DETERMINATION AND REGULATION OF THE YIELD. 



at, the forester should see, that not more is cut during the 

 working plan period, than is likely to be produced again by 

 increment during the same space of time, allowance being 

 made for any surplus or deficiency of growing stock. 



The sum total of the quantity of overwood thus ascertained 

 and of the underwood makes up the expected yield during 

 the working plan period. The executive officer should, how- 

 ever, not be forced to abide absolutely by that estimate, but 

 be permitted to modify it within certain limits in accordance 

 with requirements, as they may become manifest in the course 

 of the period, for which the working plan is drawn up. 



Intermediate cuttings occur on the areas not put down for 

 final cuttings. Their amount should be estimated in a sum- 

 mary way on the basis of local experience. 



4. The Selection Forest. 

 The selection forest resembles the coppice with standard 

 forest, since the several age classes are mixed on the area in a 

 similar manner. In the case of selection forests, it is desirable 

 to go round the whole area within a moderate number of years, 

 that is to say, to select again trees for felling over the same 

 portion of the area after a moderate interval, thus avoiding 

 having to cut too much at one time. 



The area to be taken in hand annually is obtained by 

 dividing the total area by the number of years, /, fixed as 

 above. By multiiDlying the quotient by 10, the area to be 

 dealt with during the next ten years is obtained. On the area 

 thus fixed, all mature trees are cut and the necessary thinnings 

 in the younger age classes made. The age of maturity, or the 

 rotation, is fixed as in the case of clear cutting in high forest 

 or the shelter-wood compartment system. 

 Example : — 



Area of a selection forest = GOO acres, 



Eotation = 120 years, 



/ = 20 years, 



Annual cutting area = — — = 30 acres. 



