126 ENGLISH ESTATE FORESTRY 



that of taking out the least healthy and vigorous trees, 

 independent of theii' exact position in relation to their 

 neighbours. Thinning should be carried out carefully in 

 high and exposed situations, should be conducted at frequent 

 intervals, and fir plantations gradually thinned as the trees 

 advance in height and breadth until they are about forty- 

 five years of age, after which they should not require 

 disturbing. 



The general idea which underlay the directions of the 

 above authors appears to have been that of carefully attend- 

 ing to the requirements of individual trees rather than to 

 the plantation as a whole. The general law which governs 

 individual supremacy in all crowded colonies of living 

 organisms, namely, the survival of the fittest, was ignored by 

 them, and their efforts were directed towards the prevention 

 of this law coming into play rather than taking advantage 

 of it. Indeed the great mistake, from a modern point of 

 view, that the older foresters made in all thinning operations, 

 was due to too careful and painstaking attention to what 

 they termed the " principals " of the crop. A certain but 

 comparatively limited number of these (usually hardwoods) 

 were planted to the acre, and the sole aim of the forester 

 lay in attending to and aiding their development. Modern 

 sylviculture is more liberal in stocking the ground with the 

 species it wishes to form the main crop, and is quite satisfied 

 if a fair percentage of these ultimately come to maturity. 

 It recognises the fact that length and cleanness of stem can 

 only be attained in trees which have spent the greater part 

 of their lives in a crowded wood, and that this crowded 

 condition requires the constant presence of weak and partly 

 suppressed individuals, which exclude light from the ground 

 and lower parts of the stem, and which serve the double 

 purpose of keeping the soil moist and free from weeds, and 

 preventing the growth of side branches and adventitious 

 shoots on the stems of the larger trees. The older foresters 

 religiously removed these partly suppressed trees, and it was 

 considered a sure sign of overcrowding when a few lower 

 branches were killed off by shade. Any evils that arose 

 from early thinning were supposed to be corrected, as we 

 have seen, by pruning, while the growth of surface vegeta- 



