452 



AMERICAN FORESTRY 



movement be advisable, for it is believed that every acre 

 of the interior timber will be needed for internal develop- 

 ment which must come to the interior basins of Alaska's 

 great river systems. 



The forests of interior Alaska are practically con- 

 fined to the great basins of the Yukon and Kuskokwim 

 Rivers. Some idea of the size of these areas may be 

 judged when it is stated that the drainage basin of the 

 Yukon, the fifth river in size in North America, em- 

 braces 330,000 square miles 

 (of which slightly less 

 than one-half is within 

 the Territory), while that 

 of the Kuskokwim covers 

 50,000 square miles. It is 

 probably not generally 

 known that the United 

 States owns forests with- 

 in the Arctic Circle, yet 

 the range of tree growth 

 in central Alaska extends 

 up the Chandlar and trib- 

 utaries of the Porcupine 

 Rivers, or 2 degrees inside 

 the Arctic Circle. 



The interior forests are 

 for the most part of the 

 woodland type and are 

 fairly comparable to the 

 forests of northern Maine 

 and eastern Canada, both 

 as to species and mixture, 

 though inferior as to qual- 

 ity. Of the estimated 150,- 

 000,000 acres of interior 

 forests, there are probably 

 75,000,000 acres which 

 bear timber of sufficient 

 size and quality to make it 

 of extreme value for cord- 

 wood, sawlogs, boat build- 

 ing, mining operations, 

 farm use, and other needs 

 of a pioneer region. 



The principal tree spe- 

 cies represented in the in- 

 terior forests are white 

 spruce, white birch, bal- 

 sam poplar, black cotton- 

 wood, aspen, black spruce, 

 and tamarack or larch. Of the above species the white 

 spruce is by far the most important tree. White birch 

 is widely scattered and comprises a large percentage of 

 practically all stands. Black spruce, while fairly abun- 

 dant is confined largely to muskegs and swampy areas 

 anrl is of little value. Poplar and cottonwood are abun- 

 dant along streams while aspen with white birch usually 

 forms the tree cover at timber line. 



The stand of the interior forests varies greatly with 



THEY GR.^DUALLY DISAPPEAR 



The forests along the valleys run out as the slopes are ascended, 

 the heavy stands of white spruce, white birch and cottonwood 

 becoming scattered and the trees shorter and more limby until at 

 an average of 2000 feet above sea level, tree growth practically 

 ceases. These mountains are a part of the Wrangell Range. 



the exposure and the elevation above sea level. Broadly 

 speaking, the valley floors of the Yukon and its main 

 tributaries, as well as the Kuskokwim, the Copper, the 

 Chulitna and the Susitna Rivers are timbered with 

 fairly heavy stands of white spruce, white birch, and 

 cottonwood. As one leaves the valley floor and begins 

 to go up the slopes, the forest becomes scattered and the 

 trees become shorter and more limby, until an average 

 elevation of some 2,000 feet above sea level is reached 



when tree growth ceases. 

 There is forest practically 

 along the entire line of the 

 Government railroad from 

 Anchorage to Fairbanks 

 (353 miles), except imme- 

 diately in Broad Pass and 

 except where the timber 

 has been entirely destroyed 

 by extensive fires. One au- 

 thority on Alaska condi- 

 tions estimates that there 

 are 8,600 square miles or 

 5,504,000 acres of mer- 

 chantable saw timber in in- 

 terior Alaska, and that this 

 would average not less 

 than 5,000 board feet per 

 acre. On this estimate there 

 would therefore be a total 

 of 27,520,000,000 feet board 

 measure of merchantable 

 saw-timber ; the above es- 

 timates do not include tim- 

 ber suitable only for fuel 

 and mining purposes, such 

 as stulls and lagging. 



Timber line in the Yukon 

 basin is placed about 2,500 

 feet above sea level. There 

 is a scarcity of vegetation 

 on the high ridges while in 

 some of the larger val- 

 leys of tributaries to Ta- 

 nana River the heaviest 

 stands of timber are founc. 

 A striking feature of the 

 range of tree growth is 

 found in the contrast be- 

 tween the upper reaches of 

 tributaries of the Yukon 

 and those of the Tanana. Those of the Yukon, for the 

 most part, are relatively bare, while those of the Tanana 

 are well timbered from their heads. 



The climate is characterized by long, cold winters 

 and short, hot summers with almost continuous sunlight, 

 and with a rainfall averaging less than 15 inches. As is 

 to be expected from a region in this latitude all tree 

 growth is slow. A maximum temperature of 95 degrees 

 Fahrenheit has been recorded in the Yukon basin, and 



