3. Photo crown cover (3 strata) .- -Same data as 1- -collapsed in three crown-cover 

 classes . 



4. Photo volume (500 cubic feet) class (13 strata) .- -Classes based on an estimate of 

 cubic-foot volume obtained from photo measurements of total height, crown diameter, and 

 crown coverage used with a previously compiled aerial volume table. 



5. Photo volume (1,000 cubic feet) class and topographic site (28 strata) . --Classes 

 based on estimated cubic volume obtained from photo measurements and a previously pre- 

 pared aerial volume table, and photo interpretation of topographic site. 



6. Photo volume (1,000 cubic feet) class (7 strata) . --Same data as 5--collapsed into 

 volume strata only. 



7. Photo topographic site (4 strata) .- -Same data as 5- -collapsed into four sites based 

 on aspect and position on slope. 



8. Photo species class (6 strata) .- -Plots were classified as white pine, ponderosa pine, 

 larch fir, spruce fir, lodgepole pine, and brush by photo interpretation and measurement. 



The next three methods of stratification were obtained from a standard forest type map prepared 

 by Northern Rocky Mountain Region, U.S. Forest Service. Original type delineation was on 

 aerial photos , combined with field examination and checking. These delineations were then 

 transferred to a base map of the area to prepare the finished map. Plots were located on this 

 map and classified according to the type in which they fell. 



9. Map stand size and density (9 strata) .- -Includes sawtimber, poles, and seedling- 

 saplings, and poor, medium, and well stocked classifications obtained from the previously 

 prepared type and stand-size class map of the area. 



10. Map stand size (4 strata) .- -Same data as 9--collapsed to stand size. 



11. Map density (3 strata) .- -Same data as 9--collapsed to density. 



ANALYSIS 



In the analysis all stratification schemes were evaluated for both volume and management 

 use by means of one or two selected indices. For example, net volume by species, by diameter 

 class, and by age group, growth rates, quality, and cull percents are all legitimate require- 

 ments in a volume cruise, but evaluation of each scheme by each of these factors would be far 

 beyond the scope or needs of this study. Instead, gross cubic-foot volume and gross board-foot 

 volume per acre were selected as indices to evaluate the strata for volume estimating. 



In management inventories, areas of high risk, mature, and immature sawtimber, young 

 stands in need of treatment and others where treatment might not pay off, are usual require- 

 ments together with details such as stand size , age , stem counts , and basal areas . Following 

 the above reasoning, areas of high risk sawtimber and young stands in need of treatment were 

 selected as management indices. 



Although designed to evaluate photo stratification schemes, this study also evaluates the 

 several field schemes after which most photo schemes are patterned. Classification was accom- 

 plished by data from the measured field plots but these field schemes are evaluated by means of 

 the same indices used for the photo schemes, and their value is therefore comparable. 



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