CHAPTER 2. DISTURBANCE AND FOREST 

 HEALTH IN OREGON 



OREGON COAST RANGE (M242A) 

 AND WESTERN CASCADES (M242B) 



Ecology 



Steep, highly dissected mountain slopes 

 dominate the topography of the Oregon Coast 

 and western Cascade Ranges. Because of the 

 marine influence, the coastal region has the 

 warmest winters, coolest sum- 

 mers, and greatest rainfall in 

 Oregon. More than 100 inches 

 of rain fall on the western slopes 

 of these ranges; the drier eastern 

 slopes of the Coast Range aver- 

 age only 30 inches per year. Al- 

 though July through September 

 is very dry, fog contributes sig- 

 nificant moisture along the coast 

 and lower western slopes. 



Douglas-fir dominates forests 

 of the Coast Range, extending 

 from near sea level to about 

 4,000 feet. A pioneer species 

 that reproduces after fire or other 

 disturbances, its long life span 

 allows it to persist during ex- 

 tended stable periods and re- 

 seed an area after a disturbance. 

 Forests of the lower mountain 



slopes and the coastal fog belt are dominated 

 by Sitka spruce, western hemlock, and west- 

 ern redcedar. Other conifers in the Coast 

 Range include grand fir, noble fir. Pacific yew, 

 and lodgepole pine. Red alder is the most 

 abundant and important deciduous species in 

 coastal forests. 



Ivow and mid elevations of the western Cas- 

 cades are dominated by Douglas-fir and west- 

 ern hemlock, with western redcedar, bigleaf 

 maple, and red edder common in drainage bot- 

 toms. As elevation increases. Pacific silver fir, 

 noble fir, subalpine fir, mountain hemlock, 

 lodgepole pine, sugar pine, and Engelmann 

 spruce increase in importance. Western white 

 pine is a minor component, and whitebark pine 

 is common along the crest. 



All Species 

 Fires are infrequent but severe — ^In the 



western Cascades and the Coast Range, the 

 interval between fires is generally long. When 

 fires do occur, they are large and severe, kill- 



In the Oregon Coast Range, the most notable fire in recent history 

 was the Tillamook bum, which destroyed 255,000 acres of forest 



land in the I 930s. Phow courtesy of the Oregon Historical Society (neg. 55029). 



Oregon — 25 



