166 A MANUAL OF FORESTRY. 



favourable circumstances for some time beyond it. Hence 

 the wood must be cut over for the first time at a period 

 not beyond the end of the principal height-growth. 

 After that, the rotation depends on the required descrip- 

 tion of material (firewood, hop-poles, bark of a certain 

 quality, etc.), and the time up to which the stools are 

 capable of vigorous reproduction. 



The increment of coppice woods is also greatest during 

 early youth, which is another reason for short rotations. 



c. Soundness of Stools. 



Diseased stools often produce diseased shoots, though 

 some species, as Oak and Hornbeam, are usually 

 exempted from this liability ; the same holds good in the 

 case of suckers. It follows that diseased stools should 

 be removed and replaced by strong plants to produce 

 fresh and sound stools. 



The longevity of the stools is closely connected with 

 their health, which is principally governed by the species 

 and the character of the locality. A fertile soil and 

 favourable climate increase the longevity. The stools of 

 Ash, Maple, Birch, and also those of Beech, are short- 

 lived, lasting frequently not longer than two or three 

 rotations; those of Oak and Hornbeam are almost in- 

 destructible, and between these extremes many inter- 

 mediate stages exist. 



d. Manner of Cutting. 



The cut produced by the removal of the stem is ex- 

 posed to the effects of air, moisture and sun, which 

 cause a deterioration of the wood near the cut through 



