In table 17. these 5 types are grouped as 3 types. 

 The yello\v buch-sugar inaple-beech type, the hard- 

 w'ood-spruce-fir type, and the hardwood-white pine 

 t^'pe are all included in the maple-birch-beech forest 

 type: Forests in which 50 percent or more of the stand 

 is maple, beech, or yellow birch, singly or in combi- 

 nation. (Common associates include hemlock, elm. 

 basswood, and white pine.) 



The ash-maple-elm type appears in tabic 17 as the 

 elm-ash-cottonwood forest type: Forests in which 50 

 percent or more of the stand is elm, ash, or cottonwood. 

 singly or in combination. (Common associates in- 

 clude willow, sycamore, beech, and maple.) 



The oak type is listed in table 17 as the oak-hickory 

 forest type: Forests in which 50 percent or more of the 

 stand is upland oaks or hickory, singly or in combina- 

 tion, except where pines comprise 25 to 49 percent, in 

 which case the stand would be classified "oak-pine." 

 (Common associates include yellow-poplar, elm. ma- 

 ple, and black walnut.) 



Diameter Classes 



Two-inch tree diameter classes were used. For ex- 

 ample, the 10-inch class includes trees 9.0 to 10.9 

 inches. Diameter is measured outside bark at a point 

 4^2 feet above the ground (d. b. h.) 



Tree Classes 



Sawtimber trees. — Trees of commercial species 

 that contain at least one merchantable sawlog as de- 

 fined by regional practice and that are of the following 

 minimum diameters at breast height (d. b. h.) : Soft- 

 woods 9 inches and hardwoods 1 1 inches. (Merchant- 

 able sawlogs must be at least 8 feet long, and not less 

 than 6 inches in diameter if softwood or not less than 8 

 inches in diameter if hardwood.) 



PoLETiMBER TREES. — Trccs of Commercial species 

 that meet regional specifications of soundness and 

 form, and are of the following diameters at breast 

 height: softwoods 5 to 9 inches; hardwoods 5 to 11 

 inches. (Such trees will usually become sawtimber 

 trees if left to grow.) 



Seedling-and-sapling TREES. — Live trees of com- 

 mercial species less than 5 inches in diameter at breast 

 height and of good f onn and vigor. 



Cull trees. — Live trees of sawtimber or poletimber 

 size that are unmerchantable for sawlogs now or pro- 

 spectively because of defect, rot, or species. 



Stand-size Classes 



SA^vTIjSIBER STANDS. — Stands with sawtimber trees 

 having a minimum net volume per acre of 1,500 board- 

 feet. International '4 -inch rule. 



Poletimber stands. — Stands failing to meet the 

 sawtimber stand specification, but at least 10 percent 

 stocked with poletimber and larger trees, and with at 

 least half of the minimum stocking in poletimber trees. 



Seedling-.and-sapling ST.A.NDS. — Stands not qual- 

 ifying as either sawtimber or poletimber stands, but 

 having at least 10-percent stocking of trees of com- 

 mercial species, and with at least half the minimum 

 stocking in seedling-and-sapling trees. 



Stocking. — Stocking is the extent to \shich grow- 

 ing space is effectively utilized by present or potential 

 growing stock trees of commercial species. "Degree of 

 stocking" is synonymous with "percent of growing 

 space occupied" and means the ratio of actual stock- 

 ing to full stocking for comparable sites and stands. 

 Stocking may be measured in terms of number of 

 trees, volume, basal area, cover canopy, or other 

 criteria. 



NONSTOCKED AND OTHER AREAS NOT ELSE- 

 WHERE CLASSIFIED. — Areas not qualifying as saw- 

 timber. poletiinber, or seedling-and-sapling stands. 



Poorly stocked stands. — Stands that are 10 

 to 39 percent stocked with present or potential 

 growing stock trees. 



Well- and medium-stocked stands. — Stands 

 that are 40 percent or more stocked with present 

 or potential growing stock trees. 



Timber Volume 



Growing stock. — Net volume, in cubic feet, of live 

 sawtimber trees and live poletimber trees from stump 

 to a minimum 4-inch top (of central stem) inside bark. 

 (Deductions are made for rot only. Volume in rough 

 standard cords, bark included, is derived from cubic- 

 foot volume by applying a factor of 80 cubic feet per 

 cord.) 



Sawtimber volume.- — Net volume in board-feet. 

 International y4-inch rule, of live and salvable dead 

 sawtimber trees of commercial species to a merchant- 

 able top. (The merchantable top diameter, inside 

 bark, is 6 inches in softwoods and 8 inches in hard- 

 woods. Deductions are made for both sound defect 

 and rot. The volume of salvable dead trees is 

 negligible.) 



30 



Forest Resource Report No. 8, L. S. Department of Agriculture 



