LIFE ZONES 13 



(Elyniiis spp.) and June Grass {Koeleria. cristata). The 

 precipitation in this zone is probably between 15 and 20 inches 

 annually and the maximum temperature rarely over 90° F., 

 usually less than that. 



4. Canadian Zone. This zone is hard to separ- 

 ate from the Transition Zone, and the line of demarcation 

 from the zone above it is equally indefinite in this State. The 

 commonest trees are the Bristle-cone Pine {Piniis aristata), 

 Limber Pine or Western White Pine (Pinus flexilis) the 

 Douglas Spruce or Fir (Psetidotsuga mucronata), the Balsam 

 (Abies concolor), the Quaking Aspen {Populus tremtdoides), 

 and one or two willows of the Transition Zone (Salix spp.) 

 The most characteristic grass of this zone is the Arizona 

 Fescue (Fcstuca arhonica), but this grass goes higher and 

 lower occasionally. Several species of sedges and rushes 

 occur freely in the zone. 



5. Hudsonian Zone. This is a narrow poorly 

 defined zone just below timber line. Its characteristic trees 

 and shrubs are the Siberian Juniper (Junipents sibirica), 

 Engelmann's Fir (Picea engelmanni), Parry's Fir (Picea 

 parryana), two or three species of Currants (Ribes 

 montigemuu, R. coloradense), and a low Willow (Salix 

 glaucops). A number of species of sedges (Carex spp.) and 

 rushes (Jtincns spp.) are common, while the grasses are all 

 low, the genus Fcstuca being most common. 



The temi)erature in the last two zones is never very 

 high, probably rarely over 80' F., and the season is short: the 

 precipitation will average between 20 and 25 inches annually 

 and much of it comes as snows in the winter time. 



6. Arctic — Alpine Zone. This is the small area of 

 high mountain peaks above timber line. The vegetation con- 

 sists of a few low shrubs, occasional stunted trees of the zone 

 below, grasses and herbs. Several species of Willows 

 (Salix spp.) from a few inches to 2 or 3 feet high, the Arctic 



