THE MANAGEMENT OF PLANTATIONS. 



45 



with certain advantages over their fellows, by which they are 

 enabled to thrive where others merely exist, and to exist where 

 others perish. These advantages are of many kinds, such as 

 exceptional vigour of growth, adaptability to the soil and situa- 

 tion, hardiness of constitution, &c, according as they may be 

 exposed to one or the other of the dangers which tend to 

 bring out the capabilities of the tree in these respects. Now in 

 a certain number of seeds, say 10,000, it is possible that 10 per 

 cent, are thus endowed with one or the other of these advan- 

 tages ; consequently we may fairly assume that the greater the 

 number of seeds or plants we have on a given area, the greater 

 the number of individuals are present which find a -congenial 

 home on that area, and therefore the chances of a good crop are 

 improved. This is why mixed plantations are not so well 

 able to produce timber of large size and good quality as pure 

 ones. In the first place, the number of individuals of any one 

 species must be reduced in proportion to the number of species 

 represented ; secondly, the struggle for existence in a mixed 

 wood results in the survival of the fittest species, instead of the 

 fittest individuals of any one species. At first sight, this latter 

 fact may not appear to be of any disadvantage, but rather the 

 reverse ; but we will look into this later on. 



Let us now watch the gradual development of this struggle 

 for existence in the growth of the plantation we left a few 

 moments ago, which we will suppose to consist of one species 

 only. The first thing we shall notice is the pushing ahead of a 

 certain number of trees above the heads of their neighbours, and 

 each successive year makes this difference in growth more 

 apparent. In like manner, the trees next in point of size and 

 vigour to the leading or dominant ones get ahead of those 

 weaker than themselves, so that we can divide the trees into 

 three classes according to their size. As we have already seen, 

 all have an equal chance of existing until their side branches 

 come in contact with one another and the struggle begins. 

 So long as the leading shoots are not interfered with, the 

 existence of the trees is not in any great danger, but the loss of 

 side branches checks the absolute growth of all classes as soon 

 as close order is obtained. The effect of this check upon the 

 dominant trees is at first very slight and scarcely perceptible. 

 It is more apparent upon the second class, but in both 



