occurred during the summers of 1984 and 1985. A total of 

 56 sites (280 seedling plots) were sampled in the Douglas- 

 fir/white spirea h.t., 70 sites (350 seedling plots) in the 

 grand fir/mountain maple h.t., and 24 sites (120 seedling 

 plots) in the grand fir/blue huckleberry h.t. 



The data from this study were not weD suited to statis- 

 tical analysis because the number of seedlings sampled of 

 each species inadequately represented all the various silvi- 

 cultural method-site preparation combinations, and the 

 distribution of sampling plots throughout the combinations 

 was not uniform. Rather, this was intended as a retrospec- 

 tive study of the effects of the various treatment combina- 

 tions on the occurrence of natural tree regeneration. 



I summarized the data by harvest-regeneration treat- 

 ments, site preparation treatments, and amount of shade 

 cover. For these summaries, the results are expressed as 

 percentages based on the average number of seedlings for 

 each treatment. Averages resulted from dividing the num- 

 ber of seedlings in a treatment by the number of treat- 

 ments. Average number of years to establishment after 

 disturbance were obtained by subtracting the seedling age 

 from the disturbance age and averaging the results for 

 each species in a habitat type. The average is a weighted 

 average based on the number of seedlings of each species. 



To evaluate the effect of the safe site components 

 (seedbed or cover), an "index of regeneration efficiency" 

 (RE) was calculated. The RE values were obtained by 

 dividing the percentage occurrence of seedlings in a safe 

 site component by the percentage occurrence of the safe 

 site component. Percentage occurrence of seedlings is the 

 percentage of seedlings that were found on or under a 

 safe site component based on the total number of seed- 

 lings. Percentage occurrence of a safe site component was 

 obtained by multiplying constancy of the safe site compo- 

 nent (percentage occurrence over all plots) by average 

 cover of each component. The values were totaled for all 

 covers or seedbeds, and the totals were used to obtain 

 percentage occurrence of a particular safe site component. 

 The percentage occurrence of seedlings used to obtain RE 

 values is not the same as the percentages used for the 

 previous summaries. This is because average number of 

 seedlings per safe site component could not be obtained 

 since the area occupied by each component varied from 

 plot to plot. For this reason, RE values were used for 

 these summaries. A regeneration efficiency of 1.00 in- 

 dicates that the seedlings occurred in a particular safe site 

 component in proportion to the occurrence of the compo- 

 nent. Indexes greater than 1.00 indicate that seedling oc- 

 currence was much higher on a particular component than 

 the occurrence of the component, and indexes less than 

 1.00 indicate that seedling occurrence is much lower than 

 the occurrence of the component. Using this index, possi- 

 ble beneficial or detrimental effects of the safe site can be 

 indicated. The following subjective categories and classes 

 were assigned to RE values: 



Class 1: to 0.25, very inefficient 



Class 2: 0.26 to 0.75, inefficient 



Class 3: 0.76 to 1.50, efficient 



Class 4: 1.51 to 3.00, moderately efficient 



Class 5: 3.01 and greater, very efficient. 



RESULTS AND DISCUSSION 



Approximately 370 seedlings per acre (920 per ha) were 

 found in the Douglas-fir/white spirea h.t. (table 1). Regen- 

 eration was greater in the grand fir forests with 480 seed- 

 lings per acre (1,190 per ha) in both grand fir/mountain 

 maple and grand fir/blue huckleberry h.t. Of the seedlings 

 in the Douglas-fir/white spirea h.t., 64 percent were 

 Douglas-fir, while ponderosa pine made up 24 percent of 

 the total. In the grand fir forests, grand fir accounted for 

 49 percent in the mountain maple h.t. and 50 percent in 

 the blue huckleberry h.t. Douglas-fir was also common. 

 The average number of years to establishment after 

 disturbance varied by species and by habitat type (table 1). 

 Overall, seedling establishment took longest in the cool 

 grand fir/blue huckleberry h.t. and was shortest in the 

 moderate grand fir/mountain maple h.t. 



Seedbeds 



The most common seedbed safe site component in all 

 three habitat types was litter-covered mineral soil followed 

 by bare mineral soil and moss mats (table 2). Rocks or 

 stumps, rotten wood, and residual duff were less common. 

 Residual duff was amassments of organic material that 

 had accumulated under the predisturbance stand and had 

 remained intact following the disturbance. Litter-covered 

 scarified soils were mineral soils that had been exposed 

 during the disturbance and were accumulating litter. Moss 

 mats were composed primarily of juniper haircap moss 

 (Polytrichum juniper inum), which produces loose, erect 

 stems and was usually found on scarified soils. 



In many cases RE values were very efficient or moder- 

 ately efficient for seedlings on residual duff, rotten wood, 

 or moss mats. The RE values were mostly inefficient and 

 efficient for seedlings on litter-covered and bare mineral 

 soil. In other areas, investigators have found that seed- 

 lings often occurred on seedbeds of rotten wood or duff. 

 Knapp and Smith (1982), in the Medicine Bow Mountains 

 of southeastern Wyoming, and Day (1964), in the Crows- 

 nest Forest of southwest Alberta, found that Engelmann 

 spruce seedlings occurred on rotten wood and moss mats 

 in a larger proportion than would be expected from the 

 area occupied by the seedbed (RE value greater than 

 1.00). Day (1964) also found that "mineral soil with incor- 

 porated humus" and "fermented and humified humus" 

 were very efficient seedbeds for Engelmann spruce. 

 Harvey (1982) states that rotten wood and humus provide 

 a more favorable seedbed than does mineral soil because 

 mineral soil gains and loses nutrients rapidly, has low 

 nutrient and moisture holding capacities, and changes 

 temperature quickly, whereas humus and decayed wood 

 gain and lose nutrients slowly, have high nutrient and 

 water-holding capacity, and change temperature slowly. 

 Soil organic matter such as humus and decayed wood also 

 increase the ability of the soil to support mycorrhizae, par- 

 ticularly on dry slopes (Harvey and others 1976). 



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