Procedure 

 for determining 

 tlie timber 

 base 



Forest land is usually quite easily distin- 

 guished from nonforest land on aerial photo- 

 graphs. The usual procedure in making timber 

 inventories is to begin with the total forested 

 area and then identify those areas not suitable 

 or available for timber use, using physio- 

 graphic, soil, hydrologic, ecologic, and land-use 

 information. After the forest land suitable and 

 available for timber growing has been identi- 

 fied, this area must be stratified in a way that 

 reflects degree of suitability and availability for 

 timber production, types or kinds of manage- 

 ment needed, and product output options. 



There are some areas that are either not suit- 

 able or not available for inclusion in present 

 timber growing plans. These areas can be divid- 

 ed into six general classes: ' 



'/f is important to recognize the currentness of the 

 timber growing base classification. There is nothing 

 permanent about the decisions in forest land classifica- 

 tion. For example, areas presently regarded as usable 

 for timber growing may not be so regarded a decade 

 from now, as better information about the land be- 

 comes available or because of changed land use deci- 

 sions. Likewise, areas now considered unsuitable or un- 

 available for timber growing may later be regarded as 

 usable. 



(1) Forest land formally set aside for wil- 

 derness, primitive areas, etc. 



(2) Forest land that does not meet mini- 

 mum productivity or wood quality 

 standards. 



(3) Forest land that is too unstable or too 

 steep to be logged without damage to 

 environment. 



(4) Forest land that occurs in small isolated 

 patches that are not practical to utilize 

 and which often have higher value for 

 other purposes. 



(5) Forest land administratively withdrawn 

 from timber use in multiple use plans. 



(6) Forest land being considered for wilder- 

 ness or other uses that would preclude 

 timber utilization, but for which a deci- 

 sion has not been made. 



The underlying problem in past inventories 

 has been the inadequacy of information about 

 the land, its ecology, and land use. This study 

 was conducted, therefore, only after consulting 

 National Forest staff specialists who developed 

 more complete information on geomorphol- 

 ogy, ecology, and land use. This information 

 then provided the basis for timber inventory 

 classification. Details are discussed later in this 

 report. 



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