22 BULLETIN 544, U. S. DEPARTMENT OF AGRICULTURE. 



hardwood leaves. In the spring the warm rains and sun start fer- 

 mentation of this mulch, and while this at first affords conditions 

 exceedingly favorable to the germination of the spruce seed, the 

 young seedlings are unable to survive the continued heat and humid- 

 ity and the general smothering effect of the hardwood leaf litter. 

 The trouble thus seems to be not that the seedlings are unable to 

 get their roots into mineral soil or other suitable material as is usually 

 claimed, but that the heavy mulch prevents them from getting their 

 shoots up into the needed light and air. 



FORM. 



The form of spruce varies widely and is determined largely by its 

 stage of development and whether it grows in the open or in the 

 forest. Like all other conifers, however, it always develops a well- 

 defined central axis. In the open and before arriving at the stage 

 in the forest where its lower limbs begin to be suppressed, spruce has 

 a long, wide-spreading, conical-shaped crown, which extends well 

 down to the ground. Its bole tapers rapidly. This form is retained 

 to a large extent throughout life by the trees growing in the open, 

 although their crowns open out and become less regular in outline 

 with advancing age. In the forest the crown is more compact and 

 has a conically topped head. As the tree grows in height the crown 

 becomes shorter in proportion to the total height through the lower 

 branches dying out more rapidly than new ones can be produced 

 above. The bole at the same time takes on a more cylindrical form 

 below the crown. Trees growing in the selection forest are likely to 

 taper a little more rapidly than those in the even-aged stands, since 

 they receive more side light and thus retain a longer crown than the 

 more densely crowded, even-aged ones. 1 



LENGTH OF LIFE AND MAXIMUM SIZE. 



Spruce may be classed as one of the longest-lived trees in the 

 eastern United States, ranking with the white oak in this respect. 

 In a virgin stand spruce seldom matures under 200 years, and the 

 average age of the trees in such stands is undoubtedly nearer 250 or 

 300 years. According to Mr. Austin Gary, the oldest spruce which 

 came under his notice in Maine was approximately 400 years (372 



1 An example of the variable form antl development of spruce growing under different conditions is shown 

 in the following abstract from a memoir on the Adirondack spruce by the late Col. W. F. Fox, Superin- 

 tendent of State Forests, in the Report of the Forest Commission, State of New York, 1894: "A 

 spruce 20 inches in diameter growing in a clump of spruces will yield five logs 13 feet 4 inches in length, 

 while one of the same di a cal tered grow fch mixed with hardwoods will yield but four logs. In 



the one growing among hard woods after four logs have been cut from (ho trunk the diameter of the last 

 or toj> i i ill end will be from 10 to 12 inches, but the limbs above this point will be so thick and 



that the fifl h log would not be over 5 or G inches at the top and would not be accepted by the lumber- 

 man. A tree of the samo species and sizegrov tog in a clump will yield five logs becauso the shaft does not 

 diminish in si >• p fast owing to the lighter growth of limbs that form its top. While the larger spruco are 

 found scattered among the hardwoods, the tallest ones of like diameter are found growing in the spruce 

 clumps." 



