THE FORESTS OF ALASKA. 17 



wherever it best can be marketed. Natural barriers, so far unsur- 

 moimtecl. prevent it from being of benefit to the interior, where the 

 need is greatest and the price highest. Moreover, the coast forests 

 are not capable of producing a great deal of the structural material 

 that will be needed in the interior when the latter region is more 

 fully developed and made accessible by railroads. 



The annual growth of the coast forests is far in excess of the 

 local needs, and unless methods of utilization are developed which 

 will result in the export of forest products these forests can not be 

 handled rightly. 



THE INTERIOR FORESTS. 



The forests of interior Alaska are practically all included within 

 the drainage basins of the Yukon and Kuskokwim rivers. They are 

 chiefly of the woodland type, and are estimated to cover approxi- 

 mately 80 million acres, but probably not more than 4:0 million acres 

 bear timber of sufficient size and density to make it especially valu- 

 able for either cord wood or saw logs. The tree species include white 

 spruce (Picea canadensis), white birch (Betula alaskana), balsam 

 poplar (Populus balsamifera) , black cottonwood (Populus tricho- 

 carpa), aspen (Populus tremuJokles) , black spruce (Picea mariana), 

 and tamarack (Larix alashensis). Of these the white spruce is the 

 most important, since it furnishes the only saw timber of the region 

 and is also much used for fuel. White birch is extremely abundant, 

 as are also poplar and aspen, in many localities. Black spruce is 

 of general occurrence and abundant. Mixed forests of all species 

 are common, though there are occasional pure stands of each species. 



The best timber of spruce, birch, and poplar grows in the valleys 

 of the streams, particularly along the Tanana. and excellent stands 

 of birch and aspen are found also on the easterly and southerly 

 slopes of creeks which have a silt soil. This is particularly true in 

 the Fairbanks district. Black spruce predominates in the more 

 poorly drained situations. Here, as farther south, it is characteris- 

 tically a swamp and muskeg tree, though in some places abundant on 

 hill and mountain slopes. Tamarack grows sparsely in river and 

 creek valleys, but is nowhere of particular importance. 



GROWTH AND STAND. 



The stand in the interior forests varies from practically nothing in 

 areas of scrubby black spruce to 20 or more cords per acre in the 

 birch-aspen type, and several thousand board feet per acre in the 

 best white-spruce forest. The average of the timber is small through- 

 out; white spruce rarely and balsam poplar sometimes attain di- 

 ameters of from 18 to 24 inches. The average diameter in white birch 

 and aspen stands is about 8 inches, though maximums of 18 inches 

 on unusually favorable sites were noted for these species. Black 



