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A Review of Past Research on Dendrometers
Integrated Life Cycle of Wood: Tree Quality,
Processing, and Recycling, USDA Forest Service Southern Research Station–0503,
Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
Department
of Forestry, College of Natural Resources, Virginia Polytechnic Institute and
State University, 321 Cheatham Hall–0324, Blacksburg, VA 24061
Integrated
Life Cycle of Wood: Tree Quality, Processing, and Recycling, USDA Forest Service
Southern Research Station–0503, Virginia Polytechnic Institute and State
University, Blacksburg, VA 24061
The
purpose of a dendrometer is to measure tree diameter. Contact and noncontact
dendrometers accomplish this task by collecting different metrics, including
girth or distance betweentangent points on a tree stem. Many dendrometers have
been developed in the last quarter century and many have been retired. This
article summarizes instrument developments and application results, contains an
interpretation of the results, and provides guidance for dendrometer selection.
FOR. SCI. 46(4):570–576.
Additional Key Words
Instrumentation,
diameter measurement, forest inventory, mensuration
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Development
of a digital camera tree evaluation system
USDA
Forest Service, Southern Research Station, Blacksburg, Virginia
Abstract
Within
the Strategic Plan for Forest Inventory and Monitoring (USDA Forest Service
1998), there is a call to “conduct applied research in the use of [advanced
technology] towards the end of increasing the operational efficiency and
effectiveness of our program”. The digital camera tree evaluation system is
part of that research, aimed at decreasing field time and increasing the
informational value and reliability of field data. Our approach started with the
use of a commercially available, non-metric digital camera for obtaining
diameter and height measurements from individual stems. The lessons learned from
these original attempts have shown that this concept is feasible, and helped to
indicate specific areas needing improvement. Methodological improvements to be
made include using convergent images and digital range information to account
for tree lean and investigation into ways to address the faulty assumption of a
circular (or elliptical) cross section. A completely new field-ready, durable,
self contained instrument is being constructed that will digitally output image,
3 axis inclination, and range data; and compatible software is being developed
to process this data and output information according to user requirements.
Keywords
dendrometer,
forest inventory, mensuration, digital camera, instrumentation
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Joe P. McClure
Southeastern
Forest Experiment Station-Asheville, North Carolina U.S. Department of
Agriculture-Forest Service
Five
years of field tests have proved that the mirror caliper-a hand-held,
nonmagnifying, optical caliper-is a practical instrument for use in taking
upper-stem measurements (diameter outside bark) at any point on a standing tree.
Parallel lines-of-sight produce direct-reading measurements within a range of
3.5 to 16.0 inches. Accurate readings can be taken in approximately 30 seconds.
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Comparison of three dendrometers in measuring diameter at breast height
Leigh
Ann Moran
Columbus Wood Products, 1165 Kinnear Road, Columbus, OH 43212-1162
Roger
A. Williams
School of Natural Resources, 210 Kottman Hall, The Ohio State University, 2021 Coffey Road, Columbus, OH 43210-1085
Abstract
Three
dendrometers—d-tape, calipers, and Biltmore stick—were used to measure
diameter at breast height (dbh), and discrepancies that occurred among these
instruments were compared. Three methods of dbh estimation with calipers—the
quadratic, arithmetic, and geometric mean of the major and minor axis
diameter—were compared. Trees were grouped into four broad dbh classes of
1–5, 6–10, 11–15, and 16–20in. and three species—northern red oak,
sugar maple, and white ash—to determine the effect of tree size and species on
discrepancies. The d-tape consistently recorded a larger dbh than the three
caliper methods, but was not statistically different nor practically important.
The differences in recorded dbh between the d-tape and calipers increased with
tree size and were similar among northern red oak and sugar maple trees, but dbh
differences in white ash trees were significantly less than in the other two
species. The Biltmore stick’s accuracy in classifying trees into the same dbh
class as determined by the d-tape decreased as tree size increased. When
examined by species, the Biltmore stick was less accurate in this regard with
northern red oak and most accurate with sugar maple. Because the geometric
principle of the d-tape assumes a tree to have a circular shape, its diameter
estimation and subsequent basal area will usually be greater than the true
diameter and area. The use of calipers reduces this bias, but the differences
are not statistically significant. North. J. Appl. For. 19(1):28–33.
Key
Words
Calipers,
d-tape, Biltmore stick, dbh measurement
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Comparison
of Optical Dendrometers for Prediction of Standing Tree Volume
Robert
C. Parker, Thomas G. Matney
Department
of Forestry, College of Forest Resources, Mississippi State University,
Mississippi State, MS 39762
Abstract
Enhanced
sets of compatible stem profile equations were used with data collected from
felled and standing pine trees to calculate tree volumes to various top
merchantability limits. Standing trees were measured with the Criterion 400
Laser, Tele-Relaskop, and Wheeler Pentaprism. These measurements were used to
compare accuracies of the optical dendrometers for the measurement of tree dbh
and height and the prediction of tree volume from stem profile equations. The
Criterion 400 Laser was more accurate for dbh and total height measurement than
was the Tele-Relaskop or the Wheeler Pentaprism, but the accuracy differences
are not significantly different in a practical sense. Mean percent differences
in dbh measurement translated, in absolute units, to -0.05, +0.20, and -0.34in.
of the mean tree dbh for the Criterion 400, Tele-Relaskop, and Wheeler
Pentaprism instruments, respectively. Mean percent differences in total height
measurement translated, in absolute units, to 0.5, 1.6, and 1.7 ft,
respectively, of the average tree height and were not practically different. The
combined measurement data for dbh and dob16 , indicated the Tele-Relaskop would
produce more reliable volume results than the other instruments if the
dendrometer measurements were used with form class volumes. Profile equations
developed with felled-tree data produced the most consistent estimates of
merchantable height and cubic foot volume to specified merchantable top limits.
In general, the Criterion 400 produced the smallest mean differences in standing
tree measurements and profile equation predictions of merchantable height and
cubic foot volume. However, the Tele-Relaskop produced the most consistent tree
measurement and profile prediction trends. The Wheeler Pentaprism was the least
accurate of the three dendrometers.
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