REFORESTATION IN NORTHERN IDAHO 35 



tains and located in northern Idaho, support a rich coniferous 

 flora consisting of the Western larch, Larix occidenialis, the 

 white fir, Abies grandis, the Douglas fir, Pseudotsuga mucronata, 

 Englemann spruce, Picea engelmanni, yellow pine, Pinus pon- 

 derosa, white pine, Pinus monlicola, lodge pole pine, Pinus 

 contorta var. murrayana, white cedar, Thuya plicata and the 

 Western yew, Taxus brevifolia. These hills, rising to a maxi- 

 mum elevation of 4950 feet above sea level, offer an unusual 

 variety of slope exposure, canons, and moisture supply. The 

 western and southwestern slopes of these hills receive at all 

 times the full brunt of the prevailing winds which sweep across 

 the many miles of open prairie and desert of south central Wash- 

 ington and northern Oregon and not infrequently attain a ve- 

 locity of 50 miles an hour. These wind-swept slopes are clothed 

 with a fairly dense growth of Douglas fir, tamarack, and yellow 

 pine except in sheltered ravines where one may find the white 

 cedar, the white fir and an occasional spruce. Pure forests of 

 yellow pine are not unusual, but mixed forests of pine and Douglas 

 fir, or of tamarack, white fir and cedar are more abundant, and 

 it is interesting to note that where reforestation has occurred, 

 slopes formerly occupied by any one of these forest tj^pes have 

 in most instances been reclothed with the same species. 



Figure 3 shows a north slope which was cut over more than 

 25 years ago, while in figure 4 the steep southern exposure just 

 opposite is shown. A belt transect 2 meters wide from near the 

 top of the north slope to its foot showed this forest to be com- 

 posed of 30% tamarack, 26% white fir, 39.5% cedar, 4% red fir, 

 and 0.5% yellow pine. The exposed opposite slope was studied in 

 a similar manner and revealed a decidedly different composition 

 with 10% tamarack, 40% white fir, 14% red fir, and 36% yellow 

 pine. Superficially the north slope appears to be clothed with a 

 nearly pure tamarack forest, due to the more rapid vertical growth 

 of this species. The cedars are mostly small; in fact many are 

 mere seedlings. An actual count of the annual rings showed that 

 they came in after the other trees had by their shade made con- 

 ditions less xerophytic. Such mixed forests of tamarack, white 

 fir and cedar are very characteristic of the sheltered slopes and 

 ravines (fig. 5). The large percentage of white fir shown to occur 



