274 TENi)iN<; OF Woods. 



to establish and then to preserve those physical and chemical 

 conditions of the soil on which a health}' and vigorous growth 

 depends. The means adopted in agriculture for this i)ur[)ose 

 are working the soil and manuring. Both are expensive, and 

 in sylviculture they are only feasible in cases where the 

 increased returns at least cover the outlay ; they are therefore 

 either out of tlie question, or can be employed only to a very 

 limited extent, and the forester must endeavour to accomplish 

 what is needful by other means. Fortunately timber trees 

 are far less exacting than field crops, so that the more modest 

 means at the disposal of the forester suflfice for their healthy 

 development. 



It has been shown on page 34 that the productive power of 

 the soil in sylviculture depends on : — 



(1.) A sufficient depth ; 

 (2.) A suital)Ie degree of porosity ; 

 (3.) ,, J, ;i moisture ; 



(4.) ,, chemical composition. 



For sylvicultural purposes these conditions can be procured 

 to a sufficient extent by the following simple agencies : — 



(a.) The preservation of a suitable cover overhead ; 

 {b.) The preservation of the natural covering of the soil, 

 more especially' of humus. 



How these affect the soil has been described on page 41. 

 The principal fact is, that the activity of tlie soil and a vigorous 

 development of the crop growing on it are intimately con- 

 nected with each other, and that one exercises a healthful 

 effect upon the other. At the same time the requirements of 

 tlie one may be opposed to those of the other, and it must be a 

 leading principle that the tending of the crop should always 

 take into consideration ii ])i(ip(u- preservation of the fertility 

 of the soil. 



The above remarks lefer to the case of woods wliich are 

 fully stocked, in other words, crowded woods. Cases may 



