THE FORESTS OF ALASKA. 13 



precipitation. The frozen subsoil is practically impervious to water, 

 which accumulates in poorly drained areas and causes the many 

 swamps and " muskegs." 



FOREST TYPES. 



The differentiations between forest types are as sharp as those 

 between the topographic and climatic, and. of course, depend upon 

 them. The coast forests of southern Alaska are the northernmost 

 extension of the coast type of Washington and British Columbia. 

 The interior forests are an extension of the interior Canadian forests. 

 The forests of the Susitna and Copper river basins are somewhat in- 

 termediate in character, since these rivers rise in the interior and 

 break through the mountain barrier to the southern coast. 



On the coast of southeastern Alaska trees grow to large size ; in the 

 interior the timber is much smaller. The higher mountain areas are 

 completely above timber line. Climatic conditions in the region ad- 

 jacent to Bering Sea and on the Arctic slope make forest growth 

 altogether impossible, so there are great stretches of tundra whose 

 vegetation consists, chiefly of moss, sedges, and a few small shrubs. 

 Moss may be said to be the garment of Alaska, and layers of it 12 

 to 18 inches thick are not at all uncommon either on the coast or in 

 the interior. 



Plate I (frontispiece) . from Professional Paper Xo. 15, United States 

 Geological Survey, shows roughly the forest distribution in Alaska. 

 With this map as a basis and making reductions for some barren 

 areas which it includes as forested, it is estimated that the total forest 

 and woodland area of Alaska is approximately 100 million acres, 

 or about 27 per cent of the land surface of the territory. Of these, 

 about 20 million acres may possibly bear timber of sufficient size 

 and density to be considered forest in the sense that much of it can 

 be used for saw timber, while the balance, or 80 million acres, is 

 woodland which bears some saw timber, but on which the forest is 

 of a smaller and more scattered character and valuable chiefly for fuel. 



There is not sufficient information upon which to base any satis- 

 factory estimate of the total stand of timber in Alaska. It has 

 been estimated, for instance, that the coast forests contain 75 billion 

 feet of merchantable saw timber, but this estimate might be much ex- 

 ceeded were both the spruce and hemlock closely utilized. More than 

 twenty cords per acre have been cut in good stands of birch and 

 aspen in the interior, but. on the other hand, there are large areas of 

 black spruce that is too small to u^e for any purpose; so that it is 

 still impossible to give a satisfactory estimate of the total stand. 



THE COAST FORESTS. 



The coast forests of southeastern and southern Alaska are nearly 

 all included in the Tongass and Chugach National Forests, which com- 



