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ALBERT R. MANN
LIBRARY

New York STATE COLLEGES
OF
AGRICULTURE AND Home ECONOMICS

AT

CORNELL UNIVERSITY

 

 

 

 

 

 

 
Cornell University Libra

comparison of methods of timber estima
A COMPARISON OF METHODS OF TIMBER
ESTIMATING

A Report

Presented to the Faculty of the Graduate School

Cornell University

For the Degree
of

Master in Forestry
by
Shien Sung Hu

L916
Grr,
SD
SSS

H¥7

322830
A COMPARISON OF METHODS OF
TIMBER KSTIMATING

Methods applied:

Two woodlots, the "Slim Jim" and "Meads", have been es-
timated during the course of study, and four methods were used
on each plot. They are:

1) Narrow Strip Method:

The instruments used in this method are one pair of
c&lipers, one staff compass, one 66-foot chain and @ note-book
to tabulate the results. Two men form @ working crew. The
compass is first set at the corner of the woodlot and the direc-
tion obtained by Loosening thé “Sonpess screw and reading the
bearing. Following the direction, the crew measures two or
three chains ahead, the number depending upon the regularity of
the stand. In a more regular and even-aged stand, as in ifeads
Woodlot, one strip for every three chains is measured while in
an irregular and wmeven-aged stand such as the Slim Jim, one
strip for every two chains is necessary. After the crew has
measured two chains parallel to the edge of the woodlot, the
compass is set and turned at right angles to the original bear-
ing into the woods. One chain is measured ahead, the caliper-
man holding the head end of the chain and the note-keeper the
rear end. The latter also attends to the setting and reading
of the compass bearing. The caliper-man then measures the d.b.h.
of every tree above 6" thirty-three feet on either side of the

chain. The note-keeper tabulates the results by the ot-system"
and a@lso records the number of chains measured.

When the other end of the woodlot is reached, the note-
keeper sets the compass and turns it wtil it reads the original
bearing. Two or three chains more are measured ahead where the
compass is again set and turned at right angles into the woods
(180 degrees to the first turn). Then one chain after another
is measured ahead and the d.b.h. of the trees recorded until the
other end of the woodlot is reached.

This process is repeated until all the trees above 6" on
the strips have been measured. A strip 10 chains long and 1
chain wide is equivalent to an acre; therefore, if a stand has
5 strips, each strip being 5 chains long and one strip for every
two chains, the total area of the stand would be 5 ecres.

2) The Broad-Strip Method:

This method is practically the same as the narrow strip
method except that, instead of measuring one strip in every two
or three chains, four or five chains are taken.

3) Circular Quarter-Acre Method:

Select any section which is representative of the stand,
and with the note-keeper standing in the centre, the caliper-man
measures every tree above 6" within a radius of 59 feet. The
number ot these sample plots required depends upon the size and
regularity of the stand. In estimating the Meads and Slim Jim
Woodlots, three sample plots were taken on e@ch plot, and by
averaging the volume of the timber found on these circular plots,
an average volume for the plot(one-fourth of an acre) is ob-

tained.
4) Tree-to-tree-count Method:
This is the accurate method. Every tree above 6" is
measured. For every tree calipered, a chalk-mark is made at

right angles to the direction in which the crew is proceeding.

Computation of the Volume of the stand:

After the stands have been measured, the results are
put down in a tabulated form and the volume of the stand estima-
ted by applying volume tables. In this study, the volume of
white pine in board feet is obtained by applying the "Volume
Table for Trees Near Ithaca" (Based on tables in bulletins 96,
36 and others, with values for appropriate heights from height
curve. Data by class in Forestry 11), while the volumes of
white oak, red oak, and "miscellaneous" composed of all the trees
other than the three specified, are estimated in cubic feet, and
the "Cubie Volume and Heights for Hardwoods--Cornell University
Woodlots" constructed by B. H. Paul is used in its application.
Site 3 is used.

The sum total of the results in the white pine column
is the volume of white pine in board feet for the whole stand.
The same is true in white oak, red oak, and "miscellaneous",
and the total of the three columns gives in cubic feet the vol-

ume of the stand for hardwoods and hemlock which is the only

other conifer in the two woodlots measured (Tree-to-tree-count
method). Por the strip and circular-plot methods, the volume
of the stand is obtained by dividing the total acreage of the
woodlot by the area estimated, and multiplyimg the result by the

total volume obtained.
Remarks;

The estimating of the Meads Woodlot by the nerrow and

broad strip methods was done in the fall of 1914. Five strips
were measured in applying the narrow-strip method and three in
the broad-strip method. The other two methods were done in the
months of April and May 1916.

The estimating of the Slim Jim Woodlot was started
during the Spring kecess of 1916 and finished in the middle of
May. kight strips were measured in the narrow-strip method and
four in the broad-strip. the work was done while the process
of cordwood-cutting was being carried on. But considering the
facts that Slim Jim is more irregular and uneven-aged and that
cutting was being carried on during the course of study, it is
surprising to note that, as @ whole, the comparative results

in Slim Jim @re more wniform than those obtained from Meads.

helative accuracy of the four methods used:

The most accurate method is the "tree-to-tree-cowmt",
second, the narrow strip, third, the broad strip, and fourth the
sample plot. In a small and uneven-aged stand such as Meads or
Slim Jim, the only way of obtaining accurate results is by using
the accurate method. In using the strip methods, it is apt to
run into strips with only very few trees on them, as in the
middle part of Slim Jim. In applying the sample plot method,
there is a tendency to select, instead of the most representa-
tive, the denser portions of the stand, thereby greatly ex-

ageerating the volume of the stand.
In conclusion, it can safely be said that, in a lerge,
even-aged and open stand, the broad strip method is sutficiently
accurate and sample plots may be taken to serve as @ check to
the results. In an irregulér and uneven-aged stand, the narrow
strip method should be used, but in estimating a small and wneven-
aged stand, it is fair to say that the accurate method is the
only one to be used in order to avoid exaggerating or under-

estimating the wolume of the stand.

NOTE: The broad strip method has been misinterpreted.
Instead of measuring one strip in every 4 or 5 chains as des-
cribed the width of the strips is larger than those in narrow-

strip method.
Meads Woodlot
Combined Data Of The Four Methods
Volume Computed From Field \'easurements

White Pine White Oak Red Oak Miscal's
(board feet) (cu. ft.) (ou, ft.) (ou,rt,)

Broad Strip 17,875 5308 1076.3 1879.5
Narrow Strip 26,655 1288.9 1235.2 2860.6
Sample Plot 1,900 283.9 155.7 831.5
Accurate Method 65,395 4002.7 3604.7 5532.8

Total volume Of stand computed from field measurements

White Pine White Oak Red Oak Miscel's
(bd ,ft.) (cu.ft.) (cu.ft) (eu.ft.)
Broad Strip 79,375 2654.0 5381.5 9377.5
Narrow Strip 79,695 38667 3705.6 8581.8
Sample Plot 51, 300 7665.3 4203.9 14350 .5
Acc. Method 65,3954 4002.7 3604.7 5532.8

Volume per Acre

White ine White Oak Red Oak Miscel's

(bd ft.) (cu.ft.) (ceu.tt.) (cu.£t,)
Broad Strip 13,770 393.1 979.2 1392.2
Narrow Strip 11,807 592.9 547.5 1271.4
Sample Plot 7,600 1136.8 622.8 2126.0

Acc. Method 9,658 592. 534.0 819.6
Total volume of h'dw'ds Volume of h'dw'ds p

ah Cust ws per Acre in ecu, ft.
Broad strip 17, 433.0 2582.7
Narrow strip 16,104.1 2385.8
Sample plot 26219.7 3884,1
Acc. method 13140.2 1946.9
Note: Total area of Meads Woodlot------- 6.75 acres

Average width of woodlot---------- 4.5 chains
Slim Jim Yoodlot
Combined Data Of The Four Methods
Volume computed from field measurements

White pine White oak Red oak Miscel's

(ba tt.) Low tt.) (eu, ft.) (AR Tt.)
Broad strip 7540 713.3 1148.0 14140.8
Narrow strip 13975 1943.1 2657.1 3190.1
Sample plot 1295 185.2 3523.9 415.8
Accurate method 27025 2990.5 4978.3 7414.9

Total volume of stand computed from field measurements

White pine White oak Red oak “‘iscel's.

(bd ft.) (cu.t6.) (cu.ft) (cu.ft.)
Broad strip 31668 2995.8 4821.6 5925.3
Narrow strip 29347 4080.5 5579.9 6699.2
Sample plot 26547 37966 6639 .9 8523.9
Ace. method 27025 2990.5 4978.3 7414.9

Volume per Acre

White pine White oak Red oak lMiscel's,

(od .£%.) (cu.ft, ) (ou. ft.) (euctt.)
Broad strip 6193 585.1 941.7 1195.3
Narrow strip 5732 796.9 1089.9 1308.4
Sample plot 5185 741.5 1296.9 1664.8

Ace. method 5278 684.1 Ocak 1448.2
Total volume of htdwtds Volume of h'dw'ds

am cu. Ft. per acre in cu.ft.
Broad strip 13742 .7 268 4.1
Narrow strip 16359 .6 3195.4
Sample plot 18960.4 3703.2
Acc, method 15383.7 500 4.6
Note; Total area of Slim Jim------- 5.12 acres

Average width of woodlot-----3 chains
b