of county and municipal lands was obtained from 

 the county offices; State lands from State offices; 

 Indian, O. & C. revested grant, unappropriated 

 public domain, and national-park lands from 

 various offices of the Department of the Interior; 

 and national-forest land from Forest Service 

 records. 



The area of the various types and subtypes — seg- 

 regation by age class and degree of stocking — 

 in each section was computed for each ownership 

 class from the original township field vellums. 

 Type areas in surveyed townships were computed 

 by a method known as square counting in which 

 a celluloid scale divided into %-inch squares was 

 used as an overlay on the field vellum. Type areas 

 in unsurveyed townships were determined by use 

 of a polar planimeter. A summary of the type 

 areas, by ownership class, was made, first, for each 

 township and, finally, for each county. 



The area of the site classes in each township was 

 computed by planimetering and the percentage of 

 the total area of the township occupied by each 

 site class was then determined. From these com- 

 putations site statistics by county, survey unit, and 

 region were summarized. 



VOLUME COMPILATIONS 



In order to obtain satisfactory estimates of 

 volume of standing timber it was necessary to have 

 for each of the commercial saw-timber species an 

 accurate volume table that could be applied 

 throughout the region. Investigation and check 

 of the existing tables showed that some of them 

 could be used as they were and others could be 

 made usable by adjustment and extension to 

 include larger trees, but that for some species new 

 tables would have to be made. 



The ponderosa pine table, made by James W. 

 Girard in 1932, was based on a diameter factor of 

 67 percent, which assumes that the diameter 

 inside the bark at small end of the average 16-foot 

 log is 67 percent of diameter at breast height. The 

 table was based on a top-diameter utilization 

 ranging from 40 to 60 percent of diameter breast 

 height, with an average of approximately 50 

 percent, which corresponded to actual top utili- 

 zation in the region at the time the table was made. 

 In checking the table against actual scale in several 



parts of the region 428 felled trees were measured. 

 The variation of the volume-table scale on average 

 areas ranged from -f- 1.9 percent to —4.5 percent, 

 but for all trees averaged —0.29 percent. 



The sugar pine table was also constructed by 

 Girard in 1932 in the same way as the ponderosa 

 pine table and was based on a diameter factor of 

 60 percent. The top diameter varied from 8 

 inches for small trees to 20 inches for large trees. 



For western white pine, a species of limited occur- 

 rence in the region, the Girard-Bowman table made 

 in 1932 for the Inland Empire of northern Idaho 

 and northeastern Washington was used. This table 

 was based on a diameter factor of 65 percent for 

 20-inch trees and 57 percent for 60-inch trees; the 

 factor for other d. b. h. classes was read from a 

 curve. Top diameter varied from 6 to 12 inches. 

 This table was thoroughly checked in the Inland 

 Empire and found to be satisfactory. 



The Ochoco National Forest table made by E. J. 

 Hanzlik in 1913 was used for lodgepole pine .and 

 whitebark pine. 



For Douglas-fir along the Cascade Divide, Gir- 



ard's table made in 1932 for the Douglas-fir 



region was used. In making this table the formula, 



D. b. h. + 4 ,-,',. 



— -z equals the diameter of the average 1 6- 



foot log, was used for trees 32 inches d. b. h. or more, 

 and below this diameter the average estimated form 

 and taper was used. For the remaining Douglas-fir 

 and for western larch, Girard's diameter-factor 

 table for western larch and Douglas-fir was used. 

 In making this table the diameter factor varied from 

 60 percent for 20-inch trees to 54 percent for 50-inch 

 trees and top diameter varied from 8 to 14 inches. 

 Girard's western hemlock table, based on the 

 D. b. h.+* 



formula 



equals the diameter of the 



average 16-foot log, made for the Douglas-fir region, 

 was selected for western hemlock and mountain 

 hemlock, and H. B. Steer's table was used for west- 

 ern redcedar after being adjusted to 16-foot logs. 

 Table 79 of Volume Tables for the Important Tim- 

 ber Trees of the United States: Part I, Western 

 Species, was used for Pacific silver fir, white fir, 

 alpine fir, noble fir, Shasta red fir, and Engelmann 

 spruce after being adjusted to 12-inch top and ex- 

 tended to 70 inches d. b. h. Table 91 of the same 

 publication was selected for California incense- 



