56 



DEVELOPMENT OF FOREST TREES. 



however, increase their rate of height growth considerably, 

 and this is speciallj' pronounced in spruce, silver fir, also 

 beech and oak, so that they soon reach and surpass trees 

 like ash, Norway maple, sycamore, aspen, which do not grow 

 at the same rate. 



The duration of height growth in the more advanced 

 periods of age is greatest in those species in which the 



Spruce. ■ 

 Silver Fir 

 Heecli. 

 Scotch Pin 



A(iK, IN VKAUS. 



Fig. 1.— Diagraiu illustrating tlic Relative llvujht Growtii of Spruce, Silver Fir, 

 Ikecli. and Scotch I'ine on Localities of the First Quality. 



development of stem naturally predominates over that of the 

 crown, such as spruce, silver lir, larch, ])oiiglas fir, and ^^'ey- 

 mouth i)iiic. and these species reach ultimately the greatest 

 height. 



Among Iji-uad-leaved species, sessile oak, elm and l)eech 

 preserve their height growth longest. In the case of the 

 other broad-leaved species, the crown is rounded oil' at aii 

 earlier pei-iod, when height growth ceases. 



