2 BULLETIN 55, U. S. DEPARTMENT OF AGEICULTUKE. 



wliite pine, is based partly on the actual inferiority of balsam fir to 

 those species and partly to insufficient familiarity with the wood. 



To determine impartiaUy the economic value of balsam fir, its dis- 

 tribution, present stand and cut in the various States where it occurs, 

 as well as its quafities and possibihties as a forest tree, was the purpose 

 of two summers' study in the Adirondacks, in Maine, and throughout 

 the whole of the tree's commercial range. It was befieved that by 

 pointing out the possibiUty of using balsam fir in places where 

 originally only spruce had been used, and by learning its pecuharities 

 as a forest tree, the heavy drain upon our waning supphes of spruce 

 might be sfightly decreased, and that suggestions for the proper 

 management of our spruce forests, in which balsam fir holds an 

 important place, could be formulated. 



DISTRIBUTION OF BALSAM FIR. 



Balsam fir (Ahies halsamea Mill.) is a tree chiefly of the Northeast, 

 although it occurs here and there in the mountain ridges of southern 

 Virginia and extends westward in Canada as far as Mackenzie River. 

 (See map, fig. 1.) 



Moisture and temperature are the two main factors influencing its 

 distribution. It requires a cold climate and a constant supply of 

 moisture at its roots. A mean annual temperature not exceedmg 

 40° F., with an average summer temperature of not more than 70° F., 

 and a mean annual precipitation of not less than 25 mches evenly 

 distributed throughout the year, are the necessary conditions for its 

 growth. It extends farther north than red spruce, but is left slightly 

 behind by black and white spruce, tamarack, aspen, and paper birch. 



Though m Canada balsam fir extends almost to the Rocky Moun- 

 tains, in which it is doubtless supplanted by Alpine fir (Ahies lasio- 

 carpa),^ it does not occur in continuous large forests west of the 

 one hundredth meridian, and in the United States its western limit is 

 found in Minnesota. One of the principal reasons for this is the 

 increasmg dr}Tiess of .the air which the tree encounters in its westerly 

 distribution. The mean annual ramfall gradually decreases from 

 the east toward the west. In Maine, where balsam fir reaches its best 

 development, the rainfall amounts to 43 inches; in Minnesota, where 

 balsam is of poor development, it is less than 26 inches. Farther west, 

 in North Dakota, the annual rainfall drops to about 18 inches, and no 

 balsam fii- is found. While the increasing dryness of the air influences 

 the western distribution of balsam fif, the increasing temperature con- 

 trols its southern distribution, limiting it to higher and higher eleva- 

 tions the farther south it extends, until it gives way to Frazer fir 

 {Alies frazeri (Pursh.) Lindl.) on the highest mountains of West Vir- 

 ginia, North Carolina, and Tennessee. 



' John Macoiin. Geological and Natural History Survey of Canada: Catalogue of Canadian Plants. 

 Part HI— Apetalae, p. 473. 



