150 Practical Forestry 



indicated by broad annual rings, but with coniferous wood 

 the reverse is the case. 



8. Thinning should be commenced at the central or 

 most sheltered point of a plantation, or section of same, so 

 that the outer intact boundary may continue to form a 

 barrier to cold winds, which might prove injurious to trees 

 that had hitherto stood in close order. 



9. In economic forestry, timber trees should be cut down 

 when they have arrived at maturity or have ceased to grow. 

 With coniferous trees this generally occurs at from seventy 

 to ninety years ; but with hardwoods, excepting the ash 

 and chestnut, which are of most value, say, up to fifty 

 years' growth, the period may be greatly extended. 



10. Thinning is usually performed in autumn and early 

 winter, but it may be well to remember that at the latter 

 period the lowest percentage of moisture (about 47 per 

 cent. ) is present, and the timber consequently of the greatest 

 value for constructive purposes. 



