rydberg: vegetative life zones of rocky mountains 487 



b. Chaparral Belt 



The Chaparral is mostly made up of shrub oaks, principally of 

 the Qiierciis Gamhelii group, with deciduous leaves. The ever- 

 green oaks mostly belong to the Upper Sonoran flora. The oaks 

 often grow in pure stand in dense thickets, but often are mixed 

 with species of Amelanchier , Rosa, Symphoricarpos, Cercocarpus, 

 Ribes, and other shrubs. 



The valley and canyon flora of both these belts consist of 

 Populus Sargentii, P. Wislizeni, P. acummata, P. angustifolia, 

 Betula fojitinalis, Alnus tenuifolia, and willows. 



c. Piiion-Cedar Belt 

 This belt is characterized by an open stand of Pinus edulis and 

 Sahina mojiosperma and on the western side also of S. utahensis. 

 It may be counted to the foothills, but Merriam,^ Vernon Bailey,^ 

 and Wooton & Standley,^ refer this to Upper Sonoran Zone. 

 Although the undergrowth in it is much the same as that of the 

 Pine Belt, and though the vegetation is quite different from that 

 of the Great Basin proper, which also belongs to the Upper So- 

 noran, and plant societies from the three belts often mix, it is 

 better to leave it in the Upper Sonoran Zone as they have done. 

 It will be discussed fuller later. 



4. Western foothills of the Wasatches 



This slope is much like that of the western slope of the Southern 

 Rockies, though the Pine Belt is poorly developed, perhaps 

 destroyed by man, and in the other belts there are found many 

 immigrants from the Great Basin Mountains. The Chapparal 

 extends north to about Lat. 43°. If the Piiion-Cedar Belt is in- 

 cluded in the foothills an important element is added, viz. Pinus 

 monophylla. 



5. Foothills of the Green River Basin 



Here the Chaparral Belt has wholly disappeared and of the 

 Piiion-Cedar Belt, Sahina utahensis is the only one of the charac- 

 teristic trees left. 



1 N. Am. Fauna 3: 20. 1890. 



2 N. Am. Fauna 35: 35. 1913. 



2 Contr. U. S. Nat. Herb. 19: 31, 37. 1915. 



