THE FOUNDATIONS OF 8YLYICULTUEE. 



The natural forest vegetation of the various parts of the 

 earth consists of a large number of species of trees and shrubs, 

 each of which has its peculiar mode of gro\Yth, and thrives 

 best under certain conditions. Only a limited number of 

 species of trees possess the faculty of forming by themselves 

 healthy and flourishing woods, ^Yhile others will obtain perfec- 

 tion only if they are mixed with the former. Species are 

 called ruling, or dependent, according to whether they belong 

 to the first or second category. Owing to the great number of 

 species and the ever-changing conditions in different parts of 

 the earth, it would be altogether impracticable to deal with all 

 in a book which has for its object to teach the theory of sylvi- 

 culture. The general principles of sylviculture hold good all 

 over the world, but the illustrations must be taken from a 

 limited area. In the present volume they will be taken chiefly 

 from the timber trees ordinarily growing in Western Europe 

 on the fiftieth degree of northern latitude, and the countries 

 immediately to the north and south of it. If the more 

 important species of timber trees growing in that region are 

 classified in accordance with what has been said above, the 

 following lists are obtained : — 



Riding Species. 



Decidedly ruling. — Silver fir, beech, spruce, Scotch pine. 



Conditionally ruling. — Hornbeam, oak, larch, common alder, 



birch, willows, Austrian pine, mountain pine, Weymouth 



pine, Douglas fir. 



Dependent Species. 



Of these may be mentioned : Ash, Norway maple, sycamore, 



sweet chestnut, poplars, elms, lime, white alder, Cembran 



pine, etc. 



