268 PLANTS AND MAN 



Of the two eastern species, but one, the balsam fir, is of any 

 commercial importance. It's range includes the northeastern 

 United States, following the mountains of the Southeast as far 

 as the Virginias. In Canada it is practically transcontinental in 

 distribution, extending northward and westward to the head- 

 waters of the Yukon. A symmetrical tree of only moderate size, 

 rarely exceeding seventy five feet in height and two feet in diam- 

 eter, it requires an abundance of moisture for proper develop- 

 ment. Under favorable conditions growth may be fast during 

 youth, but the span of life is short, and in older trees wood rotting 

 fungi cause extensive damage. 



Fig. 188. — The needles of firs are rounded at the apex, distinctly flattened and 



often very fragrant. 



Five western firs are of some economic importance; the low- 

 land WHITE, SILVER, RED, and NOBLE FIRS are common in the 

 forests of the Pacific Northwest, while the white fir is best de- 

 veloped in the Sierras of California. The species vary somewhat 

 with regards to their environmental demands, but all require 

 fairly moist soils and abundant atmospheric moisture for good 

 growth. Their associates in the forest stands are principally 

 Douglas fir, sugar pine, ponderosa pine, western hemlock, and 

 Sitka spruce. It is only ten years ago that the true firs came to 

 occupy a place of importance in the western lumber industry, and 

 it seems certain that their importance is due to increase, since the 

 trees are large in size, and there are large available stands re- 

 maining. Estimates place the amount of standing timber of these 

 species at about 8 % of the total timber stand, exceeded only by 

 ponderosa pine and Douglas fir. 



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