134 ENGLISH ESTATE FORESTRY 



alone, and watch the result for forty years or so, and we have 

 an object-lesson in correct thinning up to that age. One 

 generation of men can rarely see the entire operation in one 

 particular crop, from youth to maturity ; but it is possible to 

 see all the different stages in different crops or groups, and 

 we are able to piece them together to form a whole. 



Those seedlings which took the lead at the first start off 

 will probably be found to retain that lead until they come 

 in contact with each other. A struggle then ensues for a 

 few years, which ends, sooner or later, in the survival of the 

 fittest. The latter, again, go on developing until they meet 

 once more rivals of the same size, and another struggle takes 

 place as before, and with the same result, until height- 

 growth terminates and puts a stop to it. The composition 

 of the group then consists of the ultimate survivors, which 

 maintain their position until wind or decay thins their 

 ranks. 



Such is what takes place in a wood left entirely to itself, 

 whatever the species may be, so long as it remains in good 

 health and is not broken into by wind. When, however, the 

 distribution of these dominant trees happens to be very 

 irregular, we may possibly get a number of small groups 

 more or less isolated from one another, and in such cases 

 each group exhibits in itself the same process of suppression 

 by the stronger individuals as described above. 



Again, the density of the mature crop — or, in other words, 

 the proportion of individuals which have been suppressed 

 in the perpetual struggle for existence — will vary consider- 

 ably. With shade-bearers, such as beech, hornbeam, spruce, 

 or silver fir, a much larger number will be present and a 

 smaller number suppressed than in the case of light-demanders, 

 such as oak, ash, or larch, owing to the partly suppressed 

 trees of the former being able to live under conditions which 

 would kill out those of the latter. The density, so far as 

 individuals are concerned, will also vary with the quality of 

 the soil and situation. On good localities the number of 

 individuals will be smaller, but their size larger than on 

 poor soils, owing to their dense foliage and the more rapid 

 pushing ahead of the dominant trees. On poor soils, in- 

 dividuals are more evenly matched, and have a greater 



