8 BULLETIN" 950, U. S. DEPARTMENT OE AGRICULTURE. 



Altitude has a profound effect on climate, and this is shown in tree 

 growth. The limit of merchantable timber is found at about 2,500 

 feet above sea level. 



Work in the open is possible at all times of the year, but logging 

 operations are not profitable in the short days of winter. It is likely 

 that a mill would rely on stored pulpwood for a three or four months' 

 run. In Ketchikan it is said to be necessary to use artificial lights 

 after 3 o'clock in the afternoon in December. It is stated that the 

 low summer temperature would be of advantage in sulphite-mill 

 practice. 



TIMBER AND STAND. 



The most widely distributed commercial tree on the Tongass Forest 

 is western hemlock {Tsuga hetero pJiylla) . It is a rapidly growing 

 tree, and is suitable for either mechanical or chemical pulp, either 

 alone or in mixture with other species. It is conservatively estimated 

 that it forms 60 per cent of the merchantable stand. It is being ex- 

 tensively used for pulp at a number of plants in British Columbia. 



Sitka spruce (Picea sitchensis) forms about 20 per cent of the 

 stand. It varies greatly in percentage of mixture, from pure stands 

 of 10 acres or less to stands in which it is found only here and there. 

 Spruce and hemlock form increasingly larger percentages of the 

 stand of timber toward the north. 



Other species forming approximately 20 per cent of the stand are 

 western red cedar {Thuja plicata) and yellow cypress {Chammcy- 

 paris nootkatensis) with a little cotton wood, birch, lodgepole pine, 

 and white fir. 



The stand of timber on the Tongass Forest is roughly estimated at 

 9,000 feet, board measure, per acre, and the timber forms a belt back 

 from the coast that averages approximately 1 mile in width and 

 varies from a minimum width of one- fourth mile or less to a maxi- 

 mum of 5 miles. An average stand of 20,000 feet per acre of mer- 

 chantable timber was found in a cruise of the Behm Canal Unit, and 

 individual stands of 100,000 feet per acre have been found over small 

 areas. The Behm Canal Unit, as shown on the map, has a stand of 

 approximately 1,000,000,000 feet, board measure, of which 88 per 

 cent is spruce and hemlock. Spruce is used locally for lumber, box 

 shooks, and piling ; cedar for lumber and shingles ; and hemlock for 

 lumber and piling. 



Practically all of the timber in southeastern Alaska is under the 

 control of the Government and is within the boundaries of the 

 National Forest, the exceptions being reservations and town sites. 

 The area of land in private ownership is small. 



