REC^HIREMENTS FOR LIGHT. 



31 



and moisture than on the possession of certain qualities, 

 among which is the ability to bear shade. Witli regard 

 to this power trees are roughly divided into two classes, 

 often called shade-bearing and light-demanding, follow- 

 ing the German, but better named tolerant and intoler- 

 ant of shade. (Seefigs. 27. 28.) Tolerant trees are those 

 which nourish under more or less heavy shade in early 



Fig. 28. — Heavy croons <U a tuhnunl .-^pt^cit-^. 



Washiugtou. 



iiie Alpine Fir iu northern 



youth; intolerant trees are those which demand a com- 

 paratively slight cover, or even unrestricted light. 

 Later in life all trees require much more light than at 

 first, and usuallv those of both classes can live to old 

 age only when they are altogether unshaded from above. 

 But there is always this ditference between them : the 

 leaves of tolerant trees will bear more shade. Conse- 



