SILVICULTURE. 183 



Other considerations also influence these opera- 

 tions, such as the preservation of soil moisture, 

 which is the most essential contribution of the soil 

 to tree growth, and which requires the soil to be 

 kept shaded. 



In fact, there is nothing that a forester guards so 

 jealously, next to the light conditions at the crown, 

 as the soil conditions : a soil cover free of weeds 

 and grass, and covered as amply as possible with a 

 heavy mulch of decaying leaves and twigs, and if 

 this best protection of the soil moisture be defi- 

 cient, a cover of shrubby undergrowth which re- 

 quires less water than weeds and grass — this is 

 the character of a desirable forest floor. 



Altogether it will have appeared that the entire 

 silvicultural requirements of the crop resolve them- 

 selves into one, namely, proper management of 

 light conditions, which is secured by the judicious 

 use of the axe. 



While in field crops it is customary to grow only 

 single species, in pure stands, the forester has dis- 

 covered that, as a rule, not only better results, both 

 in quantity and quality, but better protection of 

 soil conditions and especially safety against many 

 dangers from insects, frosts, and storms, etc., can 

 be secured by mixed plantations, and hence he 

 gives preference to mixed crops, although such 

 crops, composed of several species, require more 

 skill in their management. 



While the crop is developing, it is, of course, 



