NATURAL AREAS AND REGIONS 



211 



of this species are rapidly yielding to 

 lumbering and not a few to fire. 



The cedar-hemlock-grand-fir — white 

 pine type occurs on the following 

 National Forests in Idaho: 



Douglas fir — western larch type 



This type prevails in Flathead and 

 Bitterroot valleys in western Montana. 

 The larch {Larix occidentalis) is really 

 not a climax species but since it is so 

 prevalent everywhere, having gained by 

 repeated fires, its name has become 

 linked with Douglas fir in the designa- 

 tion of this association. These species 

 are of much less commercial value and 

 have therefore been less exploited than 

 western yellow pine and western white 

 pine. The larch grows on moist soils 

 from the lower edge of the forest up to 

 an altitude of 5000 ft. Douglas fir has a 

 much wider altitudinal range. The 

 mean annual air temperature in this type 

 is 40.9°F., and the annual precipitation 

 is 18 to 25 in., snowfall 70 in. and over. 

 Bird and animal life is similar to that of 

 the cedar-hemlock-grand fir type but 

 less varied and not so plentiful. 



The Douglas fir — western larch type 

 occurs on the following National 

 Forests : 



THE ENGELMANN SPRUCE TYPE 



This is characterized by Picea Engle- 

 manii. Solid areas of this type are 

 relatively rare in Montana and northern 

 Idaho. This species is not plentiful 

 around the headwaters of the Clearwater 

 drainage nor generally in Montana. It 

 is confined to the cool northern aspects 

 and canyons where the snow is deep and 

 lingers late in sununer, particularly in 

 northeastern Montana on the Blackfeet 

 and Kootenai National Forests. In- 

 dividuals or grouped specimens line all 

 the principal mountain streams. There 

 is also considerable spruce at higher 

 elevations on the forests surrounding 

 Yellowstone Park. Repeated forest 

 fires in the past have no doubt greatly 

 restricted the spruce type. This forest 

 has not been exploited. Bird and 

 animal life is much the same as that 

 noted in the Cedar-Hemlock-Grand fir 

 type. Grizzly bear and moose {Alces) 

 should be added for northwestern 

 Montana. 



The Engelmann spruce type may bo 

 studied in the following National forests ; 



(Also Glacier National Park, Bolton, Montana.) 



Douglas fir — Lodgcpole Pine Type 



Douglas fir {Pseudolsuga iaxifoUa) anil 

 Lodgepole pine {Piniis contorta) occur 

 on all of the National forests in Montana 

 and northern Idaho. It is however in 

 the higher forests of central and southern 

 Montana, where climatic conditions are 

 unsuitable for the previously described 

 types, that these two species occur in 

 greatest abundance. These species are 

 invariably found at the lower tree line 

 at 2000 ft. in Idaho, 3000 ft. in western 

 Montana and 4000 ft. in central and 

 southern Montana. In Idaho this tyiie 

 attains an elevation from 7000 to SOOO ft. 



Repeated fires greatly increase the 

 proportion of lodgepole pine, often 



