58 PRACTICAL FOREST MANAGEMENT. 



published and yield tables for chir and deodar will probably be 

 available shortly, and as these are the three principal species in 

 the United Provinces, the determination of the rotation will in 

 future be greatly simplified. Hitherto in the United Provinces 

 the determination of the rotation in sal working plans has at the 

 best been based on an unreliable and uncertain calculation of 

 measurements of diameter increment of single trees in an uneven- 

 aged forest, and at the worst a purely arbitrary figure has been 

 adopted. In the United Provinces working plans the rotation of 

 greatest volume production (for the particular class of produce 

 required) is generally aimed at. In areas of very intensive demand 

 (e.g., G-orakhpur) the produce required will be total wood (timber 

 plus fuel), and the culmination of M. A. I. curve (i.e. where it 

 intersects the C. A. I. curve) for all qualities probably falls 

 between 50 and 60 years. In other divisions where fuel is value- 

 less, the rotation for maximum timber production will be adopted, 

 especially in divisions where much of the timber is exported in 

 the round (e.g., Bahraich). For this class of produce the M. A I.. 

 for all qualities culminates about 75 to 95 years (plus 10 for 

 establishment). Again, in many divisions (e.g., Haldwani, 

 Ramnagar, Ivalagarh), sawn timber only is dealt with, but in 

 letermining the rotation for sawn timber, an important point must 

 be emphasized. The figures for sawn timber outturn are based on 

 the assumption (vide definition) that there is no heart-rot or 

 hollowness, and the M. A. I. curves culminate for the different 

 quality classes at 100 years or more. But at such rotations there 

 will certainly be a considerable proportion of hollowness and rot, 

 and in addition it is probable that the crops will have commenced 

 to open out and become more or less irregular and evenaged ; 

 hence for sawn timber outturn it will be dangerous to extend the 

 rotation beyond 80 or 90 years (plus 10 for establishment). In 

 the determination of rotations in working plans, this yield table 

 has certain obvious limitation. It has been prepared for evenaged 

 high forest, and therefore supplies no data for (a) coppice with 



