ably 8 to 10 years, resulting in a pine-domi- 

 nated forest with few snags and little woody 

 material on the forest floor. In recent decades, 

 the fire regime has shifted toward infrequent 

 high-intensity, stand-replacing fires. Fire ex- 

 clusion has resulted in substantial increases 

 in stand densities and higher proportions of 

 less fire-tolerant species. At high elevations, 

 infrequent, low- to moderate-intensity ground 

 fires were common historically. Now, high-in- 

 tensity, stand-replacing fires are more com- 

 mon. 



Root diseases have subtle but significant 

 effects on growth and survival — Several 

 native fungi cause root diseases in southwest- 

 ern Oregon. Ofparticular importance are lami- 

 nated root rot, armillaria, and black stain root 

 diseases. Most root diseases are diseases of 

 the site. Inoculum of laminated and armillaria 

 root diseases may remain viable in the wood 

 of infected roots for 20 to 50 years. They cause 

 growth loss and mortality in individual trees. 

 Across the landscape, root diseases produce 

 changes in forest species composition and 

 structural diversity. They create canopy open- 

 ings, alter vegetative succession, provide snags 

 for cavity nesters and their associates, and 

 contribute woody material to the forest floor 



Root diseases (such as laminated root rot 

 pictured above) are often overlooked because of 

 the subtle nature of their effects; however, their 

 long-term effect on growth and survival is much 

 larger than that of virtually any other forest 

 mortality agent 



and streams. Root diseases are managed by 

 favoring resistant and immune species adapted 

 to sites and by encouraging harvest practices 

 that avoid reducing the vigor of individual 

 trees. 



Dwarf mistletoes are more abundant 

 now — ^Dwarf mistletoes are distributed widely 

 in southwest Oregon, especially on the east 

 side of the Siskiyous and in the Cascades. 



Oregon — 40 



