SYLVICULTURE. 



freyi. The latter, a very close relative to ponderosa and distin- 

 guished from it by bluish shoots and needles bent towards the 

 shoots, occupies the lower Sugar Pine belt. It prefers moist ground 

 and reaches only one-half the size of ponderosa. 



Mayr groups the above trees as follows, according to their de- 

 mands on moisture: 



Demands on soil moisture: 



1. Libocedrus decurrens, 



2. Pinus jefifreyi, 



3. Abies coneolor, 



4. Pinus lambertiana, 



5. Pinus ponderosa. 

 Demands on air moisture: 



1. Abies coneolor, 



2. Pinus lambertiana, 



3. Pinus jelFreyi, 



4. Libocedrus decurrens, 



5. Pinus ponderosa. 



Abies grandis (White Fir of Northern Pacific Coast). The only 

 fir on Vancouver Island. Optimum at coast in Oregon where it 

 grows up to 300 feet high, standing alongside gigantic Cottonwoods; 

 txtends eastward across the Northern Rockies, and is the first Pa- 

 cific fir met by the traveller going west on the Northern Pacific. 

 Requires moist soil. 



Abies coneolor (White Fir of Colorado and of the Sierras). 

 Running south to the San Bernardino mountains, where it occupies 

 elevations of up to 10,000 feet. Traversing Nevada, it occurs in 

 Colorado (gardener's variety glauca). It accompanies Sugar Pine 

 and Bigtree. After Muir, always mixed with Abies magnifica, occur- 

 ing at altitudes ranging between 5,000 feet and 8,000 feet. 



Abies bracteata (Santa Lucia fir of high mountains) occurs in 

 Southern California in moist cool dells. 



Tsuga heterophylla (Black Hemlock of low elevations). A fine 

 tree, the progeny of which forms a dense undergrowth underneath 

 Douglas fir. Heavy shade bearer, requiring plenty of moisture, oc- 

 curring in Alaska, Coast range and Cascades. 



Picea sitchensis (Tideland Spruce). Along coast on very moist 

 soil in Washington, on dryer soil in Alaska, very shade bearing and 

 branchy. Stinging needles. Up to 200 feet high. 



Sequoia Washingtoniana (Bigtree). Occurring only in the Sierras 

 in scattered groups at elevations ranging from 4,000 to 7,000 feet. 



23 



