FORMATION OF MIXED WOODS. 181 



nblo to both pure and mixed woods. There are, 

 however, certain peculiarities in the formation of mixed 

 woods which it will be necessary to indicate. As the 

 number of possible mixtures is very large, a separate 

 reference to each is impossible. It must suffice to deal 

 with them in the following groups : 



(1.) Formation of even-aged woods, or in which the 

 ages of the species in mixture differ so little that they 

 may, for practical purposes, be considered as even-aged. 



(2.) Formation of mixed woods consisting of trees of 

 uneven age, such as high forest with standards, two- 

 storied high forest, &c. 



1. Formation of Even-aged Mixed Woods. 



In Chapter III. of Volume I. (page 179), it has been 

 explained that in order to preserve mixtures in which 

 the species are of the same age, the latter should show 

 nearly the same rate of height-growth throughout life. 

 "Whenever this is not the case, any species sensitive 

 to cover and likely to be outgrown by associated 

 species must be given a start, while the latter must 

 be capable of bearing the shade of the former. In the 

 absence of these conditions the species must be sepa- 

 rated, and the utmost which can be done is to place 

 them in alternating groups. Even then there is no 

 certainty that in regenerating such a wood the new 

 crop will show the desired mixture. At any rate it 

 will be clear that the regeneration of such woods 

 requires constant attention, lest one species should oust 

 another. 



