f P 

@OREST RESEARCH N,/OTE

NORTHEASTERN FOREST EXPERIMENT STATION 

pF?EST SER~~Ct Upper Darby , Pennsylvania 

@ 0 rn -OYRM EHT 0 F AGR\G~~ No. 1957 65 

Relationship Of Stump Diameter To D.b.h. 

For Pitch Pine In The Northeast 

This is the seventh report on a series of studies to 

show the relationship of stump diameter to diameter breast 

high (d.b.h. ) for commercia.lly important tree species in the 

Northeast ." This report is for pitch pine (pinus rigida) . 

In this study 859 stump-diameter measurements were 

used, ranging from 4 inches to 26 inches. Both stump diame eter and d.b.h. were measured to the nearest l/l0-inch with 

a diameter tape. To obtain diameter inside bark, bark thickness was measured with a Swedish bark gage. Stump heights 

were measured on the uphill side to the nearest l/l0-foot. 

It was found that 24 percent of the stumps left on 

logging operations were between 0.6 and 1.8 feet high; 1 

percent were higher than 1.8 feet; and 75 percent were lower 

than 0.6 foot. 

In the computations, inside -bark stump diameters were 

used to avoid inaccuracies due to unequal bark thickness, 

logging damage to bark, and bark peeling off. Stump diameters were sorted into 2-inch classes. Stun---height measurements were sorted into 0.6-foot classes within each stumpdiameter class. 

To develop an equation expressing the stump dianeter 

--d.b.h. relationship for pitch pine, the method described 

by Demin&%' was used. The following equation was obtained: 

D.b.h. = 0.963 (stump d.i.b.) +' 0.806 (stump height) - 0.339 I 

The relationships developed from this equation were worked 

out as a graph (fig. 1). 

To determine the 2-inch d.b.h. class of a pitch pine 

stump from this graph, you merely plot the intersection of 

the vertical ordinate (stump height) with the horizontal 

1 

,t 
ordina.te (stum~ diameter). For example, for a stump 16.0 

inches in diameter and 1.4 feet high, the two lines intersect about halfway between the two limits of the 16-inch 

d.b.h. class. 

Comparison of actual d.b.hefs and those calculated 

with the equation showed an average weighted difference of 

0.01 inch. The standard error of estimate for all data was 

0.298 inch. At the mean of stump diameters, you can expect 

100 percent of the estimztes of d.b.h. to fall in the correct 2-inch d.b.h. class. As the stump diameters increase 

beyond the mean of these data, the error will also increase. 

(1f you use the graph by l-inch d.b.h. classes, this 

is what you can expect: 91 percent of the estimates should 

fall in the correct l-inch d.b.h. class; and 9 percent 

should fall one class above or below it.) 

For all practical purposes this graph is expected to 

give reliable d.b. h. estimates for pitch pine anywhere in 

the Northeast. 

--FRXDERICK E. HAMPF 

Forester (~ensuration) 

Division of Forest Economics 

N~rtheastern Forest Experiment Station 

Forest Service, U.S. Dept. Agriculture 

*For earlier reports on these studies see Forest 

Resecrch Note No. 38 (xhite pine), NO. 42 (sugar maple) , No* 

43 (American beech), No. 45 (yellow birch), No. 46 (northern 

red oak) , and No. 55 (yellow-poplar). 

,, \, =iDeming, W. Edwards. Statistical adjustment of data. 

261pp., illua. Wiley & Sons, New York. 1938. 

Agriculture-Forest Service-Upper Darby 
STUMP DIAMETER - 0.8. H. RELATIONSHIP FOR 

PITCH PINE 

IN THE NORTHEAST 

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 

STUMP HEIGHT, IN FEET