TOPOGRAPHY AND LIFE ZONES OF OREGON [41] 



throughout the breeding season. Late in summer their numbers are 

 augmented by the advent of many other species that wander upward after 

 their domestic duties are fulfilled. 



ARCTIC-ALPINE ZONE 



THE ARCTIC-ALPINE Zone is represented in Oregon only as a series of 

 islands on the upper slopes of the higher peaks. It is entirely above 

 timber line, and the scanty vegetation quickly gives way to permanent 

 ice and snow where the altitude is great enough. Mount Hood, Mount 

 Jefferson, Three Sisters, and the higher peaks of the Blue Mountains are 

 the most important of these highest zone areas, and with the exception 

 of the Three Sisters and the Wallowas the areas are not large. There are 

 no trees and shrubs, the nearest approach to shrubs being the dwarfed 

 forms of the false heathers (Phyllodoce empetriformis , P. glandulosa, and 

 Cassiope mertensiana) and a little ground-hugging willow (Saltx nivalis) 

 that scarcely reaches two inches in height. The mountain-sorrel (Oxyria 

 digyna), Anemone drummondi, Lupinus lyalli, Saxifraga tolmiei and S '. caespi- 

 tosa, Pentstemon men^iesii and P. tolmiei. Veronica alpina, Eriogonum umbella- 

 tum, and Potentilla flabellifolia are showy species in the Cascades that 

 spread out between timber line and the region of ice and snow. Most of 

 these and many others likewise grow in the Wallowa Mountains and, 

 together with such true Arctic species as Silene acaulis, Eritrichium ar gen- 

 tium, dwarf daisies (Erigeron aureus, E. compositus, and E. radicafus), and 

 Saxifraga oppositifolia, mark the zone. 



No mammals in Oregon and only three breeding birds are confined to this 

 zone. In the Cascades, Hepburn's Rosy Finch breeds in small numbers on 

 Mount Hood, Mount Jefferson, and Three Sisters, while in the highest 

 part of the Wallowa Mountains the Gray-crowned Rosy Finch and the 

 American Pipit are regular summer residents and breeding birds. 



