GENERAL IDEAS. 21 



that of coppice, either of which comprises several 

 methods of treatment. 



ANNUAL YIELD. By the term annual yield we 

 mean the quantity of produce that can be taken out 

 of a forest annually on the condition that this quan- 

 tity can be maintained at a constant figure. In 

 order to realize it, we may take area as our basis, 

 and cut over an equal area every year. But 

 this takes for granted that throughout the whole 

 extent of the forest, equal areas of the same age will 

 yield equal quantities of produce. When the forest 

 is rather large, it seldom happens that this is the 

 case. Under these circumstances, therefore, we may 

 divide the forest into a certain number of parts, each 

 homogeneous in itself as regards productiveness ; we 

 can then treat these areas as so many working circles, 

 in each of which we may base our annual yield on 

 area, and express it in acres. 



There are other occasions when the working circles 

 are sufficiently homogeneous to admit of the above 

 system, but the nature of the various cuttings carried 

 on is such that they cannot be effectively performed 

 by removing equal quantities of produce from equal 

 areas. This case occurs in the regeneration cuttings 

 of high forests. The annual yield is then based on 

 volume, and is expressed in cubic feet. To deter- 

 mine the amount, all the trees in the block to be 

 regenerated are counted and measured, and the 

 cubic content thus obtained is divided by the number 

 of years in the period. The quotient represents the 

 number of cubic feet to be cut each year, and this 

 amount is obtained from areas that vary every 



