sampled in this experiment on both good and 
poor sites are tabulated below: 
Diameter High-density Low-density 
distribution stands stands 
(a.0:h.) ‘No. trees/acre) (No. trees/acre) 
2 to 4 1190 550 
5 and 6 980 400 
7 to 9 690 440 
The highly significant regression of crown 
weight on d.b.h. shows that there are differ- 
ences in crown weight per tree at different 
sites and levels of density (fig. 2). For trees 
of the same d.b.h., individual crowns on good 
sites weigh more than crowns on poor sites, 
and crowns from low-density stands weigh 
more than crowns from high-density stands. 
A summary of crown weight per tree is shown 
in table 1. 
The quantity of slash resulting from a cut- 
ting operation can be determined by first ob- 
taining a good estimate of site and density 
from which crown weight per tree is calcu- 
lated, using figure 2. Next, the number of 
trees harvested in each diameter class is mul- 
tiplied by the appropriate crown weight per 
tree. This result is summed through diameter 
classes to obtain total crown weight for the 
operation. Whenever a stand falls in the mid- 
dle of either the site or stand density ranges, 
crown weight per tree may be interpolated 
from figure 2. 
A more convenient, though somewhat less 
accurate, method of estimating fuel weight 
in tree crowns is to use cordwood volume as 
a predictor of crown weight. Using figure 3, 
TABLE 1. — Crown weight per tree by d.b.h. and stand condition 
(in pounds, dry weight) 
ene | DBH (inches ) 
density | 4 6 8 
food site, high density 22 36 60 
Good site, low density 36 54 82 
Poor site, high density 13 28 59 
Poor site, low density 23 42 79 
GOOD SITE POOR SITE 
200 
LOW DENSITY 
HIGH DENSITY 
CROWN WEIGHT PER TREE (POUNDS DRY WEIGHT) 
2 4 6 8 10 2 
DBH (INCHES) 
LOW DENSITY 
DBH (INCHES) 
FiguRE 2. — Crown weight per 
tree for different site and 
density conditions. Equations 
for each site according to 
density conditions are as fol- 
lows (Le = log of crown 
weight per tree; D = d.b.h.; 
“" = highly significant re- 
gression ): 
A. Good site, low density: 
Le. = 1.1967 + .0893D**, 
r2 =" .170 
B. Good site, high density: 
Le. = .9072 + .1087D**, 
r2 = .91 
. Poor site, low density: 
Le. = .8590 + .1269D**, 
r=". 92 
D. Poor site, high density: 
Le. = .4394 + .1666D**, 
r2.= .93 
ta 
Q 
“~ HIGH DENSITY 
