FORMATION OF MIXED WOODS. 188 



Formerly it sometimes happened that one species was 

 raised by sowing and the other by planting, but this is 

 rarely done now-a-days. 



b. Sowing and Planting under Shelter-woods. 



This method is followed in the case of species which 

 are tender during youth, especially in respect of frost. 



If an old wood exists, and a new mixed wood, consist- 

 ing of a tender and a hardy species, is to be created, the 

 former may be sown or planted alone under the shelter- 

 wood ; then when the shelter- wood is no longer required, 

 it is removed, and the second hardy species planted in. 

 This method is followed, for instance, where Beech is to 

 be mixed with Scotch Pine or Larch. 



If no old shelter-wood is available, then the hardy 

 species is cultivated first, and when it has advanced suf- 

 ficiently to provide the necessary shelter, the tender 

 species is introduced. In this way Scotch Pine, Larch 

 and Birch are planted to serve as shelter woods (nurses) 

 for Beech, Silver Fir, Ash, Oak, and Spruce. 



c. Natural Regeneration under Shelter-woods. 



In regenerating a mixed wood, it is of first importance 

 that the shelter-wood should be composed of trees of 

 the several species in such proportion as to secure the 

 desired mixture in the new crop. In determining that 

 proportion, the relative reproductive power of the species 

 must be taken into consideration ; more especially the 

 size and quantity of the seeds, the frequency of seed 

 years, the height-growth of the species in early youth, 



