I found natural seedlings of Douglas-fir established on plots with organic matter 

 ranging in depth from to 2 inches, but the greatest stocking was on plots with about 

 1-3/4 inches of organic matter. Stocking (1-milacre) of natural Douglas-fir seedlings 

 by depth of organic matter was as follows: 





Depth 



Stocking 



(inches J 



(Centimeters ) 



(Percent) 











30 



1/2 



1.3 



33 



3/4 



1.9 



41 



1 



2.5 



50 



1-1/4 



3. 2 



48 



1-1/2 



3.8 



68 



1-3/4 



4.4 



72 



2 



3. 1 



64 



However, about all that can be said at this point is (1) that Douglas-fir can become 

 established through organic material on the surface, and (2) we need to study the 

 microsuccession of the forest floor of various habitat types before offering an ex- 

 planation of how organic matter affects young Douglas-fir seedlings. 



Vegetational competition. --Because there were so many gaps in the data for natural 

 seeding, my comparisons between levels of competition are based on planted-tree data 

 only. On habitats where the greatest stocking is t>'pically found, heavy competition 

 appears to have reduced stocking (fig. 9), but on more severe sites I found about the 



100- 



Figure 9. — On the western redcedar and western hemlock habitats, heavy competition 

 appears to have reduced stocking. On more severe sites, as many or more trees were 

 foimd where competition was greatest. 



12 



