THE FOREST ORGANISM. 



225 



tree is nourished thru its roots, unless its leaves have an abundance 

 of light and air it will not thrive and make wood. 



Even the trees most tolerant of shade in youth, like spruce, must 

 have light later or perish, and hence in a forest there is the constant 

 upward reach. This produces 

 the characteristic "long-bodied" 

 trunk of the forest tree, Fig. 71, 

 in contrast to the "short-bodied" 

 tree of the open, where the 

 branches reach out in all direc- 

 tions, Fig. 72. In this constant 

 struggle for existence is involved 

 the persistent attempt of scat- 

 tered seeds to sprout whenever 

 there is an opening. The result 

 is that a typical forest is one in 

 which all sizes and ages of trees 

 grow together. Scattered among 

 these are bushes and scrubby 

 trees, called "forest weeds," such 

 as mountain maple and dogwood, 

 Fig. 80, p. 234, which do not 

 produce timber. 



By foresters the trees them- 

 selves are classified according to 

 their size into : 



Seedlings, less than 3' high, 

 Saplings, 



Small, 3'-10' high. 



Large, 4" in diameter, at 



breast height (4' 6"). 

 Poles, 



Small, 4"-8" in diameter, at 



breast height. 

 Large, 8"-12" in diameter, 



at breast height. 



Standards, l'-2' in diameter, at breast height. 

 Veterans, over 2' in diameter at breast height. 



Fig. 71. Long- bodied White Oak of the 

 Forest. U. S. Forest Service. 



