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cover, temperature moderation, streambank erosion protection, and 

 to maintain water quality. LWD is the single most important 

 component responsible for forming the majority of habitat (e.g., 

 pools, undercut banks, instream cover, stable spawning beds, 

 channel morphology, etc.) critical to the production of salmonids 

 in the Pacific Northwest and Alaska. Research in Alaska has 

 shown that nearly all (99%) of the LWD in streams comes from 

 trees growing within 30 meters (100 feet) of the streambank. 

 Nearly 1/2 of the LWD was from trees that had stood on the lower 

 bank (less than 1 meter away) , and 95% was from trees within 20 

 meters of the stream. The distance to LWD sources, however, 

 differ between stream channel types. The quantity of LWD in 

 these pristine streams is high and is directly correlated with 

 the abundance of salmonid habitat. This stream habitat sustains 

 optimum egg-to-fry survival, provides nursery areas for 

 juveniles, serves as overwintering refuge, and yields smolts 

 (outmigrating juvenile salmon) which ultimately generate the 

 adult salmon returns from the ocean. 



Because the natural depletion rate of LWD resulting from decay, 

 fragmentation, stream export, and other events is relatively high 

 (1-3 percent per year) , a continuous supply of wood from the 

 riparian zone is needed to offset the natural loss and maintain 

 salmonid habitat. If these streams are logged down to the 

 streambank without leaving any buffer to replenish the natural 

 loss of LWD, then we predict that the level of LWD will be 

 reduced by at least 70 percent in 90 years. The abundance of 



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