3322 Chapter 27 



It is clear that tops and branches offer a substantial source of wood fiber. For 

 example, in a 40-year-old upland oak stand, material 4 inches dob or less will 

 account for 25 to 52 percent of the per-acre yield of wood — dry weight without 

 bark (table 27-128). Even in a 100-year-old stand, at least 25 percent of the dry 

 weight will be in this usually wasted material. The yield per acre from branches 

 of trees 5 inches or more in dbh can be as much as 26,000 pounds (dry weight 

 with bark) for a 40-year-old stand and as much as 40,000 pounds for a 100-year- 

 old stand (table 27-129). 



Estimating the volume in tops and branches. — Crown diameter can be 

 estimated from dbh, as discussed in section 15-2. Volumes of tops in dehques- 

 cent hardwoods can be estimated from stem diameter outside bark at the base of 

 the residual top or crown; figure 16-4 illustrates this relationship and gives the 

 regression equation. 



Crown volumes (cubic feet) in northern red oak can be reliably predicted from 

 the squared value for diameter at base of crown (DCr)^. The technique was 

 developed by Phillips and Cost (1978) based on measurements of 62 trees 6 to 24 

 inches in dbh selected from natural, even-aged stands in the mountains of North 

 Carolina. The equation is as follows: 



CV = -0.88554 + 0.10874 (DCr)^ R2 = 0.90 Sy • x = 3.87 cu ft 



(27-49) 

 where: 



CV = crown volume, wood only, cubic feet 

 DCr = diameter outside bark at base of live crown, inches 



Equations for predicting the cubic-foot volume in yellow-poplar branches are 

 given in table 16-30, and yields from trees 6 to 16 inches in dbh are listed in table 

 27-66D. The proportion of yellow-poplar crowns in small, medium, and large 

 branches is illustrated in figure 16-3. 



Regardless of crown type or species, the volume of a single hardwood branch 

 can be estimated from the diameter of the limb just beyond the limb collar with 

 equation 16-8. 



Readers needing to estimate the volume that crowns of standing trees occupy 

 in the forest, should find useful the work of Mawson et al. (1976) and Holsoe 

 (1950). 



Estimating the weight of tops and branches. — The relationship between 

 branch weight and tree dbh is illustrated in figure 16-1. 



Wartluft (1978) developed regression equations for predicting both green and 

 ovendry weights of sawtimber tops for soft hardwoods (yellow-poplar, cucum- 

 bertree, and black tupelo), for hard hardwoods (white ash, hard maple, hickory, 

 all oaks), and for both groups combined (table 27-130). Estimates of sawtimber 

 top green weight ranged from 556 pounds for an 1 1-inch soft hardwood tree to 

 4,633 pounds for a 26-inch hard hardwood tree. Estimates of ovendry weight 

 ranged from 308 to 2,993 pounds (table 16-32). The percent of treetop weight in 



