FOREST SURVEY METHOD 



AREA 



Forest area estimates for land west of the Continental Divide, 

 for four counties east of the Divide, and for reserved land were 

 determined by a complete survey. All other sections of the State 

 were sampled for forest area or were eliminated as nonforest zone. 

 Large blocks of nonforest were eliminated by the use of aerial 

 photographs and field examination. 



Class of land 



Complete : Sampling : Eliminated : 

 survey j survey ; i_ 



Total 



-Thousand acres- 



Forest land 



Commercial 



Noncommercial 



Reserved 



Total forest land 

 Nonforest land 

 Total land 



9,882 

 2,629 

 2,527 



15,038 



5,874 

 1,447 



7,321 



10,230 10,828 

 25,268 18,149 



50,225 

 50,225 



15,756 

 4,076 

 2,527 



22,359 

 71,283 

 93,642 



For land covered by the, complete survey the area was classified and 

 determined as follows: Using intensive private and public timber 

 cruises, county land records, cutting and fire records, and aerial 

 photographs, preliminary cover classifications were made in the 

 office. Subsequently the office determinations were checked and 

 supplemented by field examination. Cover types were delineated on 

 base maps and symbols were used to designate for each type the tree 

 species composition, stand condition, stocking, site, and age 

 classes. From maps the area of the various cover classes within 

 each ownership was calculated by the use of zylonite shields lined 

 in 10-acre subdivisions or by planimeter. The area data were 

 tabulated by Land Office sections and summarized by counties. 



The area sampled was classified into three categories (1) portions 

 inside national forest boundaries, (2) portions outside national 

 forest boundaries for which aerial photographs were available, and 

 (3) portions outside national forest boundaries either not covered 

 by aerial photographs or where photo costs were prohibitive. The 

 area sample for category 1 consisted of four-section blocks 



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