o 



LU 



o 

 o 



I- 

 co 



o s 



LU 

 CC 

 O 

 < 



100- 



80- 



60- 



40- 



20- 



DOUGLAS 

 FIR 



GRAND FIR 



WESTERN 

 REDCEDAR 



WESTERN 

 HEMLOCK 



MOUNTAIN 

 HEMLOCK 



SUBALPINE 



FIR 



MINERAL 

 SOIL 



■O T3 

 O O 



LITTER 



■a 



T3 



O O 



Figure 8 . -Stocking of naturally seeded Douglas- fir expressed as percent of 1-milacre 

 plots sampled. Success was better on litter-covered seedbeds on all habitats for 

 which data were available. 



Litter does not prohibit establishment of natural seedlings of Rocky Mountain 

 Douglas-fir. In fact, I found a greater percent of litter-covered plots stocked than 

 plots with exposed mineral soil (fig. 8) . Hatch and Lotan (1969) reported similar 

 findings in central Montana. Schmidt (1969) working in northwestern Montana found 

 Douglas-fir less sensitive to seedbed conditions than western larch insofar as both 

 seedling establishment and growth were concerned. Contrary to this, Shearer and 

 Schmidt (1970) found more ponderosa pine and Douglas-fir seedlings on scarified plots 

 than on undisturbed plots in western Montana. In my survey and in the study by Hatch 

 and Lotan, some bare areas were created by logging disturbance. Others may have been 

 caused by such disturbances as animal trampling, which may have caused seedling mortal- 

 ity. However, studies reported by Schmidt and by Shearer and Schmidt had definite site 

 preparation treatments; other disturbances were held to a minimum. 



When other environmental factors are equal, Douglas-fir will probably perform 

 better in mineral soil than in litter. However, the preparation of a mineral soil 

 seedbed does not seem to be as critical for Douglas-fir on some habitats as for other 

 species, such as western larch. Further research is needed before seedbed requirements 

 are knov\m for the various habitats in which Douglas-fir grows. 



Depth of organic matter . --The depth of organic matter on any relatively undisturbed 

 forest site probably depends to a large extent on the habitat type of the site. Though 

 I recorded the habitat of each plot, there were not enough data in each depth category 

 to obtain dependable averages until I combined habitats. Therefore, organic matter data 

 are confounded with habitat effects and are even more difficult to interpret than 

 seedbed data. 



11 



