EAST OF THE CASCADES 



Healthy or not? — ^Forest conditions in east- 

 ern Oregon and Washington have been steadily 

 changing for more than 100 years. Many dis- 

 turbances in forest stands have altered fre- 

 quencies or intensities compared to historical 

 ones, often outside the natural range of varia- 

 tion. Much of the change in disturbance re- 

 gimes is due to Are suppression and selective 

 harvesting in the last century. Both practices 

 have resulted in significant changes in the dis- 

 tribution and structure of forest vegetation: 

 more true fir and Douglas-fir on low-elevation 

 sites where pines and larch formerly predomi- 

 nated, many overstocked mixed conifer and 

 pine stands, and more multistoried stands. 

 Key differences between historical and present 

 disturbance patterns are described below: 



• Outbreaks of defoliating insects, such as 

 western spruce budworm and Douglas-fir 

 tussock moth, are now larger, more intense, 

 and more frequent. 



• Bark beetle mortality, associated with tree 

 stress and overstocked stands, is more preva- 

 lent. 



• Drought periods in the late 1980s and early 

 1990s, coupled with overstocking, contrib- 

 uted to increased susceptibility to insects, 

 diseases, and Are. 



• Many root diseases and dwarf mistletoes are 

 more widespread and destructive because of 

 changes in forest structure and past harvest 

 practices. 



• Fire is less frequent now but much more dev- 

 astating on lower elevation, dry sites. The fire 

 hazard on these sites is higher because of fuel 

 buildup. 



Prescribed fire reduces fuels and thins the stand by k/7//ng some of the smaller and more fire- 

 susceptible tree species. 



The Future— 79 



