ALNUS oregona: its value as a forest type 985 



Many people have no doubt noted the bunches of nodules present on 

 alder roots, but have failed to recognize their significance. Several 

 specimens of these nodules have been sent to the Madison Laboratory, 

 and examination has shown beyond a doubt that they contain nitrogen- 

 fixing bacteria and perform the same functions as leguminous crops in 

 adding nitrogen to the soil. This action is especially desirable in the 

 coast soils, since repeated fires have depleted the soils of these elements. 



The efficacy of the alder as a soil restorer has been demonstrated 

 many times. Taking two adjacent areas similar in all respects except- 

 ing that one supports a growth of alder and the other is covered with 

 fern and salal, it has been demonstrated repeatedly that the former will 

 yield excellent forage and garden crops, while the latter is practically 

 unproductive. This is especially true of bench lands. 



3. Its Value for Fire Protection 



The value of alder as a protection to the seed trees and older repro- 

 duction that have maintained a foothold throughout the various fires 

 that have swept the region has already been discussed. 



On the other hand, during the past seven years approximately ten 

 thousand acres have been replanted and seeded where natural repro- 

 duction is inadequate or entirely absent; also there are thousands of 

 acres of brush land carrying stands of very young reproduction which 

 must be protected from destruction by fire. In this respect the alder 

 growth has proven a very valuable and efficient assistant. 



A bird's-eye view of the Siuslaw Forest presents a vast network of 

 canyons and draws, each of which carries a heavy growth of alder. 

 In many instances this growth extends up both sides of the ridges, 

 meeting at the top ; in others lacking but a short distance of meeting. 



The brush ordinarily is less dense beneath the alder and any debris 

 that may be present is always moist, both of which together with the 

 moist condition of the surface soil forms a natural and efficient fire- 

 line. It is only during the seasons of exceptional drought that fire will 

 run beneath the alder, and even then it advances slowly and is easily 

 controlled. These conditions greatly facilitate the protection of the 

 reforested and reproducing areas. The necessity of building extensive 

 fire-lines is obviated, as in almost all cases conditions are such that the 

 construction of a short fire-line only is necessary to connect two alder 

 draws in order to stop a fire advancing along a ridge. Since the open 

 areas on the Forest carry a heavy growth of salal and fern, both of 

 which are very inflammable at certain seasons, the presence of this 

 alder growth is seemingly a wise provision of nature to aid in the re- 



