FOREST RESOURCES OF THE PONDEROSA PINE REGION 



Appendix 



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Methods in Inventory Phase 



Existence of considerable information, particu- 

 larly on the saw-timber areas which comprise 60 

 percent of the 22 million acres of forest land in the 

 region, permitted use of the so-called compilation 

 method in making the inventory. This method 

 consisted of obtaining information on forest-type 

 areas and timber volumes through compilation and 

 checking of existing records — such as forest-type 

 maps, timber cruises, land-exchange examinations, 

 aerial and panoramic photos, cut-over land surveys, 

 extensive reconnaissances, fire reports, and similar 

 records — from private timberland owners, or their 

 agents, and various public agencies. Areas for 

 which no reliable records were available were cov- 

 ered by intensive field reconnaissance. Field work 

 was commenced in the summer of 1934 and com- 

 pleted in the winter of 1936. 



In the compilation method all forest-type area 

 and timber-volume information was obtained in 

 place, which made possible the preparation of a 

 forest-type map and timber-volume estimate for a 

 specific area. The same procedure was employed 

 on all the forest lands in the region, regardless of 

 ownership. 



The inventory phase was conducted in four steps; 

 first, collection of existing information; second, 

 checking usable timber estimates and adjusting 

 them to a common standard; third, field examina- 

 tion of areas not covered by usable information; and 

 fourth, compilation of data collected. 



Collection of Existing Information 



The first step in the collection of existing informa- 

 tion was to compile all available timber cruises from 

 various sources. The majority of the acreage of 

 privately owned forest land in the region was found 

 to be covered by intensive cruises, either in the pos- 



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session of the owner or his agent or county cruises 

 made for taxation purposes. In the counties in 

 which the county cruise gave a complete coverage 

 of privately owned timber and was known to be 

 sufficiently consistent and reliable, no private 

 cruises were collected. Each owner who furnished 

 timber cruises was guaranteed that information ob- 

 tained from the cruises would be held strictly con- 

 fidential and released only in conjunction with 

 other cruise data. 



Intensive cruises were available for the bulk of the 

 ponderosa pine timber and for a considerable acre- 

 age of other types in national-forest ownership. The 

 Klamath, Warm Springs, Yakima, and Colville 

 Indian Reservations, and Oregon & California 

 Railroad revested grant lands in Klamath County 

 were covered by intensive surveys. 



Detailed forest-type maps of all national-forest 

 land covered by intensive surveys were available, as 

 well as generalized type maps made at the time of 

 the 1922 extensive reconnaissance of the region's 

 national forests. Although these maps were not 

 exactly in accordance with the type scheme adopted 

 by the Forest Survey and had to be checked in the 

 field and transposed to the standard scheme, they 

 very materially lessened the amount of field typing. 



Vertical aerial photos covering a considerable 

 acreage in Union and Umatilla Counties were 

 obtained from a private owner and proved .a ver} 

 valuable aid in the mapping. Also, during the 

 survey, oblique aerial photos were taken of between 

 4 and 5 million acres of rough and inaccessible 

 mountainous country in Chelan and Okanogan 

 Counties, Wash., and Wallowa, Baker, Union, 

 Umatilla, and Grant Counties, Oreg. 



Locations and year of cut of logged areas were 

 obtained from records in the offices of the county 

 assessors and private timber owners. Locations 

 of areas deforested by fire were obtained from the 



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