134 FORESTRY 



(5) General principles upon which future operations should 

 be conducted. 



As the whole course of management has its foundation in 

 the above subjects, their importance will be readily appreciated. 

 The conclusions arrived at are embodied in the Working 

 Plan report. 



Methods of Regulating the Yield 



Various methods are employed to regulate the amount of 

 produce that may annually or periodically be taken from a 

 forest without diminishing its permanent stock or reducing 

 the productivity of the soil. The simplest of these consists 

 of the division of the total forest area into sections, corre- 

 sponding in their number to the number of years in the 

 rotation. These annual felling coupes may be either of equal 

 size, or else they may vary in extent according to their yield 

 capacity and degree of complete stocking. In this their 

 acreage is determined in inverse proportion to their productive 

 value. It is evident that smaller areas of dense woods are 

 equivalent to greater areas of thin crops or poorly grown 

 woods, and the allocation can be arranged accordingly. The 

 plan of making the divisions of equal or nearly equal size 

 is suitable for coppice woods and for woods worked on the 

 Selection system. 



Of more general applicability is the method of allotting 

 the woods of a forest into Periods*. The number of the 

 period classes and the time occupied by each, depend chiefly 

 upon the length of the rotation, but intervals of twenty years 

 are frequently found to be suitable. 



Division of the forest into Periods takes place according to 

 area or volume, or regard is had to both of these factors, and 

 a method of partition by area and volume combined is resorted 

 to. 



Allotment by Area. By this system approximately like 

 areas are allotted to separate periods in the rotation. 



For example, if a forest of 12,000 acres, worked on a 

 rotation of 120 years, be treated in Periods of 20 years, 



