The number of 8-foot bolts in relation 
to d.b.h. was fitted best with a quadratic equa- 
tion of the form Y = a+b (d.bh) + ¢ 
(d.b.h.)* for both oak species and soil types. 
Differences in the regression estimates of 
cordwood heights between the various oak 
species on both Grayling and Rubicon were 
generally less than 0.5 bolt with a maximum 
of 0.6. The maximum predicted difference in 
cordwood heights in terms of cordwood vol- 
ume amounted to less than .01 cord per tree 
following diameters: 6.0, 8.0, 10.0, 12.0, and 
14.0 inches. The average deviations of the 
test trees at any one d.b.h. did not exceed 0.3 
bolt from the predicted heights in table 1, 
which was well within the desired degree of 
accuracy. 
TaBLE 1. — Cordwood height and volume of mixed 
oak on Grayling and Rubicon sands, 
by diameter at breast height 
for oak up to 11 inches at d.b.h. and .02 cord ree: er Cords per 
per tree for trees 11 inches at d.b.h. and height per sq. ft. ; 
larger. This finding suggests that one com- (inehes) vce? «||. pacalalee 
bined cordwood height-d.b.h. curve has con- 5 13 0013 0.010 
siderable practical value for determining 6 2.0 027 138 
stand volumes of mixed oak growing on the 7 26 045 169 
Grayling-Rubicon association as presented in 8 3.2 .068 .195 
table 1. Local d.b.h. volume tables may be 9 3.8 100 .226 
prepared as shown for the cordwood volumes 10 1 re oan 
in column 3 of table 1 or cordwood volume- 3 are ‘O14 073 
basal area ratios for point sampling as shown 13 52 262 ‘284 
in column 4. The cordwood volume-basal area 14 5.4 311 291 
ratio averaged 0.21 for the mixed oak stands 15 5.6 S12 .303 
used in this study. This basal area included 1 Y = — 3.372 + 1.090 (d.b.h.) — .033 (d.b.h.)2, 
only trees supporting cordwood volumes. 
The cordwood heights in table 1 were 
field checked for their accuracy in 12 addi- 
tional mixed oak stands growing in northern 
Lower Michigan on coarse sandy soils having 
no textural B horizon. The soil type in five 
of these stands was later identified as Gray- 
ling sand; in the other seven it was a Gray- 
calm sand. In each test stand cordwood height 
was measured for the first tree of each of the 
April 1963 
R= + .89, N = 1,057. 
2 Composite Volume Tables for Timber and Their 
Application in the Lake States, by S. R. Gevor- 
kiantz and L. P. Olsen, U. S. Dept. Agri. Tech. 
Bul. 1104. 1955. Table 6 (corrected to 19 per- 
cent bark volume for oak). 
3 Ratio of cords per tree (from Column 3) to 
square feet of basal area for point sample cruis- 
ing. To obtain cords for individual trees or for 
stand volumes multiply the square feet of basal 
area by the appropriate ratio computed for the 
various tree sizes. 
JOHN L.. AREND 
Research Forester 
(Forest Management) 
U.S. DEPT. OF AGRICULTURE 
NATIONAL AGRICULTURAL LIBRARY 
AUG2 0 1963 
C & R-PREP. 
