ALNUS OREGONA : ITS VALUE AS A FOREST TYPE 983 



The value of alder as a type will be shown under the following head- 

 ings: 



1. Its value as a nurse crop. 



2. Its value as a soil builder. 



3. Its value for fire protection to second growth and reproduction. 



4. Its commercial value. 



I. Its Value as a Nurse Crop 



In journeying throughout the forest the large bodies of alder present 

 themselves conspicuously to one realizing that they form such exten- 

 sive stands in a region in which the Douglas fir reaches its optimum 

 development. Scattered through this alder growth are frequent Doug- 

 las-fir trees from 40 to 70 years old. The oldest and largest of these 

 trees are found among the older alder thickets. Evidently these iso- 

 lated firs are the remnants of reproduction following the original fire 

 and which, due to their location among the alders, have escaped de- 

 struction by the numerous fires of the subsequent periods. It has also 

 been noted that as one progresses toward the outer edge of these alder 

 thickets scattered younger fir occur, which evidently resulted from the 

 seeding of those larger firs already mentioned. That these seedlings 

 are enabled to develop is due to the comparative openness of the alder 

 crown canopy. That this reproduction has survived has been due to 

 the protection afforded them by the encompassing nurse crop. 



Many examples are found where heavy fir reproduction is occurring 

 in the openings adjacent to the alder growth. In the midst of this re- 

 production young alder is rapidly springing up that will act as a future 

 protection of the more valuable conifers, which in the meantime will 

 have attained sufficient growth, so that its development will not be at 

 all affected by the alder canopy. 



Then, again, openings are found in which scattered seed trees occur 

 which have been preserved by the surrounding alder growth. In such 

 situations dense reproduction has resulted which is now crowding the 

 alder slowly, but surely, back to the canyons whence it originally came. 

 Also among the dense stands of second-growth fir, 30 to 50 years old, 

 the decayed remnants of former alder growth are frequently found, 

 showing that after the alder has served its purpose as a nurse crop it 

 ultimately yields to the Douglas fir, which forms the permanent or 

 natural forest type in this region. 



The value of alder as a nurse crop does not lay alone in the protec- 

 tion from fire afforded the more valuable species, but also from the 

 fact that it has the power of rehabilitating those soils that have been 



