Spiegel Relascope (Relaskop)
Table of Contents
Spiegel Relascope
The Spiegel Relaskop, also known as a Relaskop, is a sophisticated instrument that can be used to measure stand basal area and tree height and diameter at any point up a tree bole. In conjunction with other equipment, the Relaskop can be used in the estimation of distance (range) to an object and the number of trees/ha. Spiegel relascope is a multipurpose instrument with the help of which the following measurements can be carried out.
Structure
History
Based on the work of Dr. Bitterlich of Austria, the Spiegel Relascope was first manufactured in 1950.
Handling the instrument
Always store the instrument in the leather case when not in use.
Measurement of Height
The standard metric Relaskop has three scales for measuring (vertical) height. The appropriate scale will depend on the horizontal distance from the tree.
 leftmost scale – 20 m from the tree.
 middleleft – 25 m from the tree.
 middleright – 30 m from the tree.
 Trees less than 12 m height: Set out 10 m and use the 20 m scale, but divide final estimates by 2.
 Trees 12 – 18 m: Set out 15 m and use the 30 m scale, but divide final estimates by 2.
 Trees 18 – 23 m: Set out 20 m and read directly from 20 m scale.
 Trees 23 – 28 m: Set out 25 m and read directly from 25 m scale.
 Trees 28 – 35 m: Set out 30 m and read directly from 30 m scale.
 Trees 35 – 45 m: Set out 40 m and use the 20 m scale, but multiply final estimates by 2.
 Trees 45 – 55 m: Set out 50 m and use the 25 m scale, but multiply final estimates by 2.
 Trees greater than 55 m: Set out 60 m and use the 30 m scale, but multiply final estimates by 2.
Once the observation point is found and the appropriate scale selected, sight through the peephole to the base of the tree. Tap the brake button several times until the scale settles then read the height directly from the appropriate scale. If you are looking down towards the base of the tree, this reading is the vertical height that the base of the tree is beneath your eye. Sight to the top of the tree (or other point) and again tap the brake button until the scale settles. The scale is a direct reading of the height above your eye to this new point. Add the two heights together if the base of the tree was below your eye to determine total (vertical) height. If the base of the tree was initially above your eye (i.e. the base if above you on sloping ground) subtract the initial height from the upper height to determine (vertical) height.
Height is determined (and recorded) to the nearest quarter meter (0, 1/4, 1/2, 3/4 m) for trees less than 20 m, or to the nearest half meter (0, 1/2 m) for trees greater than 20 m.
SEE ALSO: Tree Height Measuring Instruments
Measurement of Bole Diameter
The band labeled with “1” and the four narrow (or quarter) bands alongside are used to estimate diameter.
To determine the bole diameter for a known height on the tree:
d = 4 * D
d = 2 * D * (b + (q/4))
where b equals 1 if band 1 is covered and 0 otherwise,
q denotes the number of quarter bands (read down to one fifth of a quarter band).
d = 2 * 20 * (1 + (3.2/4))
d = 2 * 20 * 1.8
d = 72 cm
p = 10 * D/d
p = 10 * 20 / 72
p = 2.8%
Thus we would expect the diameter to lie between 72 cm +/ 2 cm.
Measurement of Stand Basal Area
Bands

BAF

(Calculation)

1 quarter

0.0625

(1/16)

2 quarters

0.25

(1/4)

3 quarters

0.5625

(9/16)

Band 1

1.0

(1/1)

Band 1 + 1 quarter

1.5625

(25/16)

Band 1 + 2 quarters

2.25

(36/16)

Band 1 + 3 quarters

3.0625

(49/16)

Band 1 + 4 quarters
Also called Band 4 
4.0


Band 2

2.0


Choose the appropriate BAF and combination of bands. Then, standing over the sample point, hold the brake button down and make a sweep of 360 degrees while comparing the tree diameters at breast height with the selected bands. Count the number of trees whose diameter at breast height appears greater (wider) than the selected bands – IN trees. Ensure trees are not hidden behind closer trees by stepping to one side and checking before returning to the sample point. Where trees appear to be the same width as the selected Relaskop bands, or it is not obvious that the tree diameter is larger, measure the distance to the tree and that tree dbh and refer to the borderline calculations. Once the sweep has been completed, multiply the count of IN trees by the appropriate BAF to get stand basal area (m^2/ha).
Relascope – FAQ
Why is Relascope used for?
Spiegel relascope is a multipurpose instrument with the help of which the following measurements can be carried out:
1. Basal Area
2. Tree height
3. Slope
4. Upper stem height
5. Stand height
6. Tree Diameter
Can Relascope be used to find out Range?
Yes, A Relascope can also be used to find the distance from a tree (range). This is done in the same manner as when one uses a transit using a set of trigonometric formulae based on height and angle. The Relascope is not commonly used for this because of its difficulty and the amount of time it takes to do this.
How Relaskope is used in Point Sampling?
The Relascope is often used for point sampling. This is done by using the set spacing marked in the Relascope to gauge whether a tree is in or out of the stand. A tree is IN or OUT based on whether it fills the space between the lines on the scale in the Relascope. If it does then the tree is IN. If it doesn’t then the tree is OUT. If the tree is IN this means that it is counted as basal area within one’s plot. The basal area is obtained by multiplying the number of trees by the basal area factor, which is based on the width of the gauge.
Who invented Relascope?
The relascope was invented by Walter Bitterlich.
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