224 



NATURALIST'S GUIDE TO THE AMERICAS 



4. Important types— yellow pine, yel- 

 low anil sugar pine, Jeffrey pine, red 

 fir, : n' sugar pine i!n(' fir. 



5. Elevation from 3000 to 8000 ft — 

 average 4500 ft. 



6. Distance from Nevada CityJ, 10 mi. 



Trinity National Forest 



1. Area- 1,409,490 acres. 



2. Present condition— practically in- 

 accessible. Experimental area will be 

 established. 



3. Forest heavily grazed by sheep, 

 and to moderate extent by cattle. 



4. Important types include yellow 

 pine, mixed conifers. 



5. Elevation from 2500 to 7500 ft.— 

 average 4000 ft. 



6. Distance from ReddingJ, 30 mi. 

 Supervisor's headquarters at Weaver- 

 villet 



8. NATIONAL FORESTS OF THE 

 IKTERMOUNTAIN DISTRICT (4) 



By F. S. Baker and S. B. Locke 



The national forests of the Inter- 

 mountain Region (Utah, Nevada and 

 Southern Idaho) cover practically all 

 the forested land which bears tree 

 growth other than pinyon (Pinus edulis), 

 juniper {Juniperus utahensis and J. 

 monoftperma) , within the states of Utah, 

 Nevada and the portion of Idaho south 

 of the Salmon River. The only notable 

 exception in western Idaho is where 

 considerable areas of western yellow 

 pine {Pinus ponderosa and Pinus pon- 

 derosa scopulorum) timber land are held 

 in private ownership. Ecologically, 

 however, this area contains nothing not 

 found within the national forests ad- 

 joining. These forests lie within an 

 area of varying climatic conditions and 

 present very different appearances in 

 different portions. In every region 

 there is a typical altitudinal zonation of 

 forest types on the mountains, but 

 within the Intermountain Region the 

 zonation is quite variable from north 

 to south, while in many places it is 

 further modified by the fact that the 



high plains of the Snake River valley 

 further modify the lower lying alti- 

 tudinal types on account of the 

 topography. 



In western and southwestern Idaho 

 the plains are covered with sagebrush 

 {Artemisia trideniata) and present nearly 

 unmodified ecological conditions, and 

 will do so for a great many years to come 

 as irrigation at best is only a local 

 possibility and vast areas of this land 

 will remain in a virgin condition. Win- 

 ter grazing of sheep is practiced to 

 a certain extent and has modified the 

 herbaceous vegetation (to that degree). 



The lower slopes of the foothills are 

 usually covered with grasses, largely 6 

 weeks grass {Bromus tectorvm) which is 

 in itself evidence of greatly modified 

 vegetational conditions. It is safe to 

 say that the flora and fauna in this 

 zone have been very greatly modified 

 by grazing and fires. 



This grassy belt extends into the 

 yellow pine type which in the mountain 

 valleys usually extends directly to the 

 agricultural lands, although in the main 

 Snake River valley it is separated by 

 the grass land on the foothills mentioned 

 above. At elevations almost as low as 

 where the yellow pine first appears, 

 Douglas fir {Pseudotsuga taxifolia), is 

 found on north slopes. As altitude in- 

 creases the Douglas fir increases in 

 proportion to the yellow pine, becoming 

 more extensive on the north slopes 

 than on the flats, finally occupying all 

 the ground except rugged knobs and 

 ridge tops. This occurs at fairly high 

 elevations, however, where the potential 

 Douglas fir type is covered very largely 

 with the temporary lodgepole pine type 

 {Pinus murrayana) which has come in 

 as a result of fires. 



Still higher, lodgepole pine, alpine 

 fir {Ahies lasiocarpa), and Engelmann 

 spruce {Picea engehnannii) predomi- 

 nate. Through all the timber types, 

 fairly natural conditions exist, except 

 around the outermost edges of the 

 National forests, and around mining 

 camps. Grazing is and has been gener- 

 ally moderate and the herbaceous flora 



