140 ENGLISH ESTATE FORESTRY 



especially injured by such influence, for its bark is full of 

 dormant buds, which only require an excuse of this kind for 

 breaking out and covering the stem with shoots. These 

 shoots deprive the legitimate crown of most of its nourish- 

 ment, and although they assist in adding bulk to the stem, 

 they render its timber coarse and knotty, and induce stag- 

 headedness on the poorer soils. 



On good, deep, and fairly moist ground, of course, the 

 effects of sudden thinning are not so marked, and in all cases 

 they are less in inverse proportion to the previous thickness 

 of the wood. But in scarcely any case does it do any good 

 after the height-growth of the trees has practically ceased, 

 except to a few of the dominant trees, which already have 

 sufficiently deep crowns capable of further development. 

 Trees which possess simply a tuft of foliage at the top 

 receive, after height-growth ceases, as much light as they are 

 capable of making use of, and sudden isolation simply means 

 little more than an increased strain upon the roots in windy 

 weather. To find a crop chiefly consisting of such trees, 

 indicates either a poor soil or faulty thinning in the past, 

 otherwise such trees would have been suppressed long before. 

 In mixed plantations their presence is of course due to 

 specific differences in shade - bearing power and rates of 

 growth, and when light-demanders and shade-bearers are 

 mixed and left to themselves, the final effect is the gradual 

 crushing out of the former in this manner. But when things 

 have gone so far the remedy of course is the removal of the 

 crushed-out trees, and the remainder of the crop is little 

 influenced one way or the other. 



In thinning, much of course depends upon the class of 

 tree required or most in demand. For small sizes, such as 

 fencing or pit-wood, a different system of thinning is advisable 

 from that adopted for large heavy timber. In the former 

 case a large number of tall, clean, and moderate-sized trees 

 to the acre will constitute a more profitable crop than trees 

 with deep crowns and short thick boles. To produce such 

 a crop the system of thinning adopted should closely 

 approximate to the natural or self-thinning one. For the 

 first ten or fifteen years the crop should be gone through and 

 cleared of all suppressed or diseased individuals, and the trees 



