69 



CHAPTER III. 



CHARACTER AND COMPOSITION OF WOODS. 



In sylviculture trees are only in exceptional cases reared in 

 free positions ; as a general rule they are grown in consider- 

 able masses, which' form more or less crowded woods. Such 

 woods may be composed of one species only, or they may 

 contain a mixture of two or more species ; in the former case 

 they are called j^ure woods, and in the latter mixed icoods. 

 Naturally pure woods occur only under certain conditions, as, 

 for instance, when the factors of the locality suit only one 

 particular species, or when the vitality and energy of one 

 species has gradually ousted all others. Species which appear 

 naturally in pure woods are called gregarious. The bulk of 

 the pure woods, which exist at present in Europe, are the 

 result of artificial interference. By far the greater number 

 of natural woods are mixed. 



Section I. — Puke Woods. 



Practically, woods are rarely quite pure, because in most 

 cases specimens of other species, which it was not intended to 

 rear, make their appearance uninvited. As long as such an 

 admixture is slight, accidental and not taken into account by 

 the management, the character of the pure wood may be said 

 to be preserved. 



The principal advantage of pure over mixed woods is, that 

 they are easier to manage, because the requirements of only 

 one species have to be considered. On the other hand, they 

 have often disadvantages as compared with mixed woods, 

 which will be dealt with in section II. 



