3324 Chapter 27 



Size class and description Table number 



Understory hardwoods less than 5 inches in dbh growing in the mountains of 



North Carolina on the Georgia Piedmont 16-7 



Pine-site hardwoods 6 inches in dbh of 22 species samples throughout their 



southern ranges 7-2 



Five oak species plus sweetgum and yellow-poplar 6 to 22 inches in dbh growing 



in the Southeast . 7-2A 



STUMPS AND ROOTS 



Weights of stump-root systems are discussed in section 14-3 and in tables 14- 

 lAB and 14-2AB. Figures 14-4 through 14-26 illustrate the typical stump-root 

 shapes. Additional information is provided in section 16-1, DISTRIBUTION 

 OF TREE BIOMASS (Page 1428). 



The proportion of the complete-tree weight contributed by the stump-root 

 system varies with species, as shown by a comparison of the 22 hardwood 

 species most commonly found on southern pine sites (table 16-2). For trees 6 

 inches in dbh, the stump-roots (including lateral roots to a 3 -foot radius) ac- 

 counted for 15.4 to 25.1 percent of the complete-tree ovendry weight; the 

 average for all species was 20.6 percent. Species with small proportions of their 

 biomass in the stump-root system include yellow-poplar, the ashes, and water 

 oak. Those with massive stump-root systems include hickory, black tupelo, 

 sweetgum, and blackjack oak. 



The proportion of the complete-tree weight contributed by the stump-root 

 system also varies with tree size. In chestnut oak forests in east Tennessee, the 

 stump-root system (including laterals to a radius of 60 cm) made up 9.4 percent 

 of the complete-tree ovendry weight in trees more than 9.5 inches in dbh and 

 22.4 percent in trees between 0.5 and 3.5 inches in dbh (table 16-4). Similar 

 ranges were found in oak-hickory stands (9.8 to 18.0 percent) and in yellow- 

 poplar forests (10.7 to 16.9 percent). In a study of sawtimber-sized black oaks, 

 the stump and roots accounted for one quarter of the complete tree dry weight 

 (Tennessee Valley Authority 1972). Equations and a table for estimating stump 

 and root weight for black oaks 12 to 36 inches dbh are given in tables 27-81 and 

 27-135. 



Stump height. — The nominal stump height used by the Forest Survey in its 

 inventories is 1 foot, but in actual practice the height at which stumps are cut 

 varies. In a study of 200 logging operations in Alabama and Louisiana, mean 

 stump heights ranged from 0.37 feet for softwood pulp wood to 1.15 feet for 

 hardwood saw logs, and stump volume ranged from 0.22 to 2.51 cu ft (table 27- 

 136). 



Excessive stump heights can take a heavy toll on the volume of wood recov- 

 ered, and tables are available for calculating the loss in terms of cubic feet and 

 board feet (table 27-137). For example, if a stump 16 inches in diameter is cut 4 

 inches above the target height stated in the logging contract, 3.69 bd ft (Interna- 

 tional V4-inch rule) is wasted. The tables are based on characteristics of southern 

 pine stumps; on swell-butted hardwoods the losses may be greater. 



Relation of stump dimensions to dbh. — Foresters and timber managers 

 often need to estimate the volume of timber removed from a tract after cutting 



