15 



But in whatever way prescribed the realisation of the 

 possibility should be formulated in a simple manner, easy to 

 apply and to control, and so that it constitutes of itself the 

 main provision of the working-plan. 



A rule snoh as the following would fulfil this condition :— 



" Bach year there will he felled, hy the selection method in successive annual 

 coupes of one-tenth of the total area, a number of trees not exceeding 700, in the 

 proportion of 4 firs to 3 oaks." 



Or, were the numher of trees not prescribed and were the fellings limited hy 

 sylvioultural rules, and possibly, in addition, by the provision of a maximum volume 

 of material, the rule might be to the following effect: — 



"There will be felled, ob one-tenth of the area each year, all dead, diseased or 

 dama<;ed stems, and stems that it is otherwise desirable, for sylvicultural rea- 

 sons, to remove ; the maximum volume of material removed being limited to 600 

 cubic feet on an average per acre," 



A sustained yield.— As the crops we have to deal with in 

 India are always abnormal, it is evident that the yield, 

 although the methods devised for determining it may be the 

 best possible, will not he exactly equal or sustained from 

 period to period. Equality can no more be secured from the 

 time when the working-plan is applied, than can the normal 

 constitution of the crop be approximately attained without a 

 lapse of years sufficient for its growth. Ordinarily a fairly 

 equal yield from year to year during the length of one period 

 may be secured ; "but, especially during the provisional period 

 required for the proper constitution of the stock, even such 

 equality may be freely sacrificed in the interest of sound or 

 economical administration. 



The German foresters always compare the yield which it is proposed to remove 

 with the normal production or potential possibility as it has sometimes been 

 called in India. Unfortunately in India, owing to only a few species irregularly 

 distributed throughout the forest being saleable, or to the irregularity and incom- 

 pleteness of the crops, it is not often that the potential possibility can be ascercaiued 

 with an approximation saflScieut for comparison. 



EEVENUE AND INTEREST. 



Meaning of the terms. — The income in money derived from 

 a forest, after deductmg the cost of felling and extracting 

 the produce, may conveniently be called ihe revenue.^ The 

 net revenue is the balance of income left after deducting all 

 other charges, including the cost of maintaining and, if 

 necessary, of improving the forest. 



