TOPOGRAPHY AND LIFE ZONES OF OREGON [35] 



necked Stilt, and American Egret. Thriving colonies of these are present 

 in the Klamath Lake district, Warner Valley, and Harney Valley. In the 

 sagebrush, the Burrowing Owl, Arkansas Kingbird, Gray Flycatcher, 

 Merrill's Horned Lark, Sage Sparrow, Brewer's Sparrow, and Rock Wren 

 are common, while along the river bottoms and open valleys Mourning 

 Doves, Bullock's Oriole, the Western Lark Sparrow, and the Long-tailed 

 Chickadee may be considered characteristic birds. 



Some of these associations grow to be very real as one travels the 

 country. For example, it was no greater shock to hear the cheerful little 

 trill of Brewer's Sparrow at above 6,000 feet altitude on a hot slope in 

 the Wallowa country than to find the two-acre growth of sagebrush that 

 the bird frequented. Somehow, where one is found the other is expected 

 also, although this tiny island of Upper Sonoran was many miles from 

 the nearest extensive area of that zone. 



TRANSITION ZONE 



FROM A utilitarian standpoint, the Transition Zone, which covers broad 

 areas of the State, is the most important. Except for irrigated valleys of 

 the Upper Sonoran, most of the important agricultural areas and the bulk 

 of the commercially important timber stands lie in this zone. Like the 

 Sonoran, it is divided into humid and arid sections in Oregon, the former 

 lying west of the summit of the Cascades and the latter east of that range. 



The humid Transition Zone occupies all of western Oregon except the 

 Sonoran valleys of the Rogue and Umpqua Rivers, a paper-thin area of 

 Canadian near the coast, and a few islands of Canadian on the highest 

 peaks of the Coast Range. It extends upward onto the flanks of the 

 Cascades to an altitude that varies from 3,000 to 5,000 feet, according to 

 slope and exposure. It is a region of heavy rainfall the precipitation 

 varying from 40 inches in the Willamette Valley to upward of 80 on the 

 coast and the slopes of the Cascades. Much of the moisture of the Cas- 

 cades comes in the form of heavy snow, which furnishes water through 

 the summer to keep the cool trout streams flowing. 



On the western slopes of the Cascades through much of the Willamette 

 Valley magnificent virgin forests of Douglas fir (Pseudotsuga taxifolia) that 

 often extend for miles are characteristic and dominant, while on the 

 western slope of the Coast Range equally magnificent stands of Sitka 

 spruce (Picea sitchensis) outline the zone. Mingled with these are many 

 other coniferous trees, such as western hemlock (Tsuga heterofhylla), sugar 

 pine (Pinus lambertiana), white fir {Abies grandis), western arborvitae 

 (Thuja plica fa), and Oregon yew (Taxus brevifolia). Along the streams 

 deciduous trees, such as Oregon maple {Acer macro fhy Hum), Oregon alder 

 {Alnus oregona), Oregon ash {Fraxinus oregona), black cottonwood (Populus 



