3276 Chapter 27 



In equations 27-37 and 27-38, variables obtained from a standard prism tally 

 account for 73 and 71 percent of the variation in merchantable green and dry 

 weights, respectively. 



Another study in West Virginia (Wiant and Fountain 1980) showed that oak 

 site index by itself is a poor predictor of the aboveground biomass. The study 

 was established on the 8,000-acre West Virginia University Forest near Morgan- 

 town. This 46-year-old forest is evenaged, and approximately 62 percent of the 

 forest area is in the upland oak type, dominated by white, chestnut, scarlet, 

 northern red, or black oaks. The remainder is cove hardwood type, dominated 

 by yellow-poplar, black cherry, and northern red oak. The estimated total dry- 

 weight biomass averaged 78 tons per acre for the cove hardwood and 66 tons for 

 the upland oak type; the difference was statistically significant. However, the 

 average 50-year site index was also higher for the cove hardwood type (81) than 

 for the upland oak type (66). When data for the two forest types were pooled and 

 common regressions were computed for the components of biomass (table 27- 

 99), the correlation coefficients were highly significant in most cases, but they 

 were too low (0.30 to 0.50) for the regressions to have much predictive value. 

 Oak site index by itself accounted for only about 25 percent of the variation in 

 total tree biomass. 



Density and bulk density. — The density of wood (Ib/cu ft) is discussed in 

 section 7-1 . For the 22 hardwood species commonly found on pine sites, table 7- 

 1 gives stemwood density values for a range of moisture contents and specific 

 gravities. Density of freshly felled 6-inch trees with bark ranged from 50.7 

 pounds per cubic foot in green ash to 65.9 pounds per cubic foot in blackjack 

 oak, as shown in table 7-2. Stem and branch densities (with and without bark) 

 are also given in table 7-2. 



Small understory hardwoods (average diameter 3.0 inches) in the Georgia 

 Piedmont were more dense than comparable trees from the mountains of North 

 Carolina (tables 7-3 and 16-7). 



Trees 6 to 22 inches in dbh have green wood and bark bulk densities that vary 

 with species and location in tree (table 7-2 A). Freshly felled wood of chestnut, 

 northern red, scarlet, southern red, and white oak is more dense than water; 

 sweetgum wood, when green, has density about equal to that of water, and 

 yellow-poplar wood has lower density than water. Green bark of these species in 

 trees sizes 6 to 22 inches is less dense than water, as follows (table 7-2 A): 



Whole-tree density 



Species Wood Bark 



— Poundslcu ft — 



Chestnut oak (North Carolina 65 53 



Northern red oak (North Carolina) 65 62 



Scarlet oak (Tennessee) 67 61 



Southern red oak (Tennessee) 66 59 



White oak (North Carolina) 65 54 



Sweetgum (Georgia) 63 48 



Yellow-poplar (North Carolina) 52 49 



Bulk density of green wood varies with wood specific gravity and moisture 

 content, and these vary within and among trees as detailed in chapters 7 and 8. 



