Diameter breast height (d.b.h.) 



The diameter of a tree at a point 4^ feet above the ground on the tree's 

 uphill side. Height of d.b.h. may vary on abnormally formed trees. 



Desirable tree 



Live noncull trees of commercial species are divided into two classes: 

 desirable and acceptable. For a tree to be desirable it must be free 

 from disease, of good form, potentially not more than 10 percent defect 

 of disease or fire scar, of good vigor, and not excessively limby if saw- 

 timber. A tree will be considered to have good vigor if it has 40 per- 

 cent or more crown (exception: ponderosa pine, and aspen may have on- 

 ly 30 percent crown to be classed as desirable). It is the kind of tree 

 that would be favored in cultural operations or featured in management 

 in under rotation-age stands. Mature trees (over rotation age) of com- 

 mercial size with less than 20 percent defect and expected to live 10 

 years are low-risk trees and may also be classed as desirable trees. A 

 species which is not adapted to the site should be classified as sound 

 cull. 



Diameter Classes 



A classification of trees based on diameter outside bark, measured at 

 breast height (4i feet above the ground). Note: D.b.h.. is the common 

 abbreviation for diameter at breast height. Two-inch diameter classes 

 are commonly used in Forest Survey, with the even inch of the approxi- 

 mate midpoint for a class. For example, the 6-inch class includes trees 

 5.0 through 6.9 inches d.b.h., inclusive). 



Farmer-rancher lands 



Lands owned by individuals with a minimum of 40 acres. 



Fixed radius plot 



For this inventory a 1/300 acre (6.8 feet radius), circular plot, located 

 at each sample point on which live trees up to 4.99 inches d.b.h. are 

 tallied. 



Forest industry 



Lands owned by companies or individuals operating wood-using plants. 



Forest land 



Land at least 16.7 percent stocked by forest trees, or formerly having 

 such tree cover, and not currently developed for nonforest use. Forest 

 land does not include land currently developed for nonforest uses such 

 as urban or thickly settled residential or resort areas, city parks, 

 orchards, improved roads, or pasture lands improved by such measures 

 as seeding or irrigation. The minimum area for classification of forest 

 land is one acre. Roadside, streamside, and shelterbelt strips of timber 

 must be at least 120 feet wide to qualify as forest land. Unimproved 

 roads, trails, streams, and clearings in forest areas are classed as 

 forest land if they are less than 120 feet wide. 



Forest types 



A classification of forest land based upon the dominant species forming a 

 plurality of stocking based on area occupied in the present tree cover. 



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