THE ROLE OF FIRE IN FOREST SUCCESSION 



Frequent low-in I en si ly fires maintain open-grown pine ecosystems 

 by limiting the establishment and growth of shade-tolerant species (itiner cycle). With fire 

 removedfiom the ecosystem, dense stands of shade-tolerant firs develop that are highlly 

 susceptible to insect and disease epidemics and high-intensity stand replacement fires 

 (outer cycle). 



PACIFIC DOUGLAS-FIR TYPE 



Douglas-fir forests of the Pacific slope (the wesUvard side of the 

 Cascade Range) are long-lived and extremely productive. Stands 

 of Douglas-fir were typically regenerated about every 300 years 

 by high-intensity stand-replacement wildfire. Harvesting on short 

 rotations, intermediate cutting, continuous cropping of Douglas- 

 fir on the same sites, and widespread planting of Douglas-fir on 

 sites formerly occupied by other species are some of the factors 

 associated with a significant increase in root disease damage in 

 this type (Byler 1988). Tree mortality is severe on some sites, and 

 productivity of stands is greatly reduced. Douglas-firs replanted 

 immediately in areas with root disease problems are quickly in- 

 fected, and tree losses begin early in the rotation. 



Healthy Forests for America 's Future — A Strategic Plan 



11 



