Measures and yields of products and residues 327 1 



Taras listed green cordwood weights for some individual species, three of which 

 are commonly found on pine sites: 



Species Bark and wood Wood free of bark Bark 

 Pounds/cord-- 



Sweetgum 5,670 4,880 790 



Blackjack oak 5,760 4,700 1 ,060 



Green ash 4,930 4,320 610 



Based on the assumptions that a cord contains 80 cu ft of solid wood and that 

 airdry wood contains 20 percent moisture content in terms of ovendry weight, 

 Page and Wyman (1969) listed the following weights for airdry hardwoods: 

 Species Pounds/bark-free cord 



Ash 3,440 



Elm, American 2,960 



Hickory, shagbark 4,240 



Maple, red 3,200 



Oak, red 3,680 



Oak, white 3,920 



Weight of saw logs. — The weight of saw logs can be computed from general 

 knowledge of unextracted specific gravity and moisture content together with 

 bark volume and specific gravity as previously noted for cordwood. The variable 

 form of logs makes such computations difficult, however. Schumacher (1946) 

 was among the first to explore volume- weight ratios. Row and Guttenberg 

 (1966) reviewed the effects of log taper, log shape, trim allowance, bark volume 

 and specific gravity, and wood moisture content and specific gravity; they 

 concluded that total log weight was best expressed by an equation of the follow- 

 ing form: 



W - a,D2L + aJDU + a,V (27-24) 



where: 



W = log weight, pounds 

 D = scaling diameter, inches 

 L = scaling length, feet 

 a,, a2, and sl^ = constants determined by regression analysis of weights of 

 sample logs 



Hardwood log weights determined by direct measurements (table 27-70 

 through 27-80) have been published by Massengale (1971), Timson (1972), 

 Phillips (1975), and Clark (1976). 



Weight of individual trees and parts. — Numerous studies have been made 

 of whole-tree or merchantable stem weights. The most relevant ones are summa- 

 rized below. Predicting equations and weight tables contained in this book are 

 listed by species at the end of this subsection. In addition, section 16- 1 , DISTRI- 

 BUTION OF TREE BIOMASS, page 1428, contains information on whole-tree 

 and stem weights, both in pounds and as a percentage of total tree biomass. For 

 weights of bark see chapter 13, for roots chapter 14, and for foliage chapter 15. 



The 22 hardwood species commonly found on southern pine sites show 

 considerable variation in weight. When trees 6 inches in dbh were sampled (see 

 tables 3-1 and 16-3 for dimensions), green weight of the above-ground tree parts 



