Dendrometer
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==Kramer's Dendrometer== | ==Kramer's Dendrometer== | ||
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The Dendrometer (according to [http://de.wikipedia.org/wiki/Horst_Kramer Kramer]) is a simple measurement device that is suitable for the estimation of [[basal area]] per hectare based on the principle of [[Bitterlich sampling]], stand volume and rough estimates of tree height and volume partitioning of single trees (Kramer 1990<ref name="kramer">Kramer, H. 1990. Nutzungsplanung in der Forsteinrichtung. 2., überarbeitete und erweiterte Auflage. J.D. Sauerländer’s Verlag, Frankfurt/Main.</ref>, Akca 2001<ref name="akca">Akca, A. 2001. Waldinventur. J.D. Sauerländer's Verlag. Frankfurt am Main, 193 S.</ref>). The Dendrometer II is manufactured and distributed by the | The Dendrometer (according to [http://de.wikipedia.org/wiki/Horst_Kramer Kramer]) is a simple measurement device that is suitable for the estimation of [[basal area]] per hectare based on the principle of [[Bitterlich sampling]], stand volume and rough estimates of tree height and volume partitioning of single trees (Kramer 1990<ref name="kramer">Kramer, H. 1990. Nutzungsplanung in der Forsteinrichtung. 2., überarbeitete und erweiterte Auflage. J.D. Sauerländer’s Verlag, Frankfurt/Main.</ref>, Akca 2001<ref name="akca">Akca, A. 2001. Waldinventur. J.D. Sauerländer's Verlag. Frankfurt am Main, 193 S.</ref>). The Dendrometer II is manufactured and distributed by the | ||
[http://www.uni-goettingen.de/en/67094.html Department of Forest Inventory and Remote Sensing] at the university of Göttingen. | [http://www.uni-goettingen.de/en/67094.html Department of Forest Inventory and Remote Sensing] at the university of Göttingen. | ||
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===Height measurement=== | ===Height measurement=== | ||
It is possible to roughly estimate [[tree height]] based on the [[The geometric principle|geometric principle]] with the Dendrometer. Therefore hold the device vertically in front of the eye (opening on top) and aim at the tree to be measured. Adjust the distance of the Dendrometer from the eye or your distance from the tree until the points ''k'' and ''h'' correspond to the tree tip resp. to the bottom of the trunk. The relation of the section ''hi'' to line ''hk'' is 1:10. the height of point ''i'' corresponds to 1/10 of the tree height. In order to calculate the tree’s height measure the distance from ''i'' on the tree to the tree base and multiply by 10. It should be considered that the measurement of tree heights is just a "side function" of this device, while the main purpose is in estimation [[basal area]]. | It is possible to roughly estimate [[tree height]] based on the [[The geometric principle|geometric principle]] with the Dendrometer. Therefore hold the device vertically in front of the eye (opening on top) and aim at the tree to be measured. Adjust the distance of the Dendrometer from the eye or your distance from the tree until the points ''k'' and ''h'' correspond to the tree tip resp. to the bottom of the trunk. The relation of the section ''hi'' to line ''hk'' is 1:10. the height of point ''i'' corresponds to 1/10 of the tree height. In order to calculate the tree’s height measure the distance from ''i'' on the tree to the tree base and multiply by 10. It should be considered that the measurement of tree heights is just a "side function" of this device, while the main purpose is in estimation [[basal area]]. | ||
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===Estimation of basal area per hectare=== | ===Estimation of basal area per hectare=== | ||
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When a width of 2 or 4 is used, the resulting basal area (number of trees counted) must be multiplied by the corresponding factor (2 or 4) in order to obtain estimates of basal area per hectare. | When a width of 2 or 4 is used, the resulting basal area (number of trees counted) must be multiplied by the corresponding factor (2 or 4) in order to obtain estimates of basal area per hectare. | ||
With relascope sampling on slopes it is necessary to multiply the estimated basal area per hectare with the coefficient k (k=1/cos α) for the respective maximal inclination of slope from the table on the Dendrometer. | With relascope sampling on slopes it is necessary to multiply the estimated basal area per hectare with the coefficient k (k=1/cos α) for the respective maximal inclination of slope from the table on the Dendrometer. | ||
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===Determining value of single trees by estimating volume sections=== | ===Determining value of single trees by estimating volume sections=== | ||
Revision as of 14:42, 27 September 2011
Contents |
Kramer's Dendrometer
The Dendrometer (according to Kramer) is a simple measurement device that is suitable for the estimation of basal area per hectare based on the principle of Bitterlich sampling, stand volume and rough estimates of tree height and volume partitioning of single trees (Kramer 1990[1], Akca 2001[2]). The Dendrometer II is manufactured and distributed by the Department of Forest Inventory and Remote Sensing at the university of Göttingen.
Height measurement
It is possible to roughly estimate tree height based on the geometric principle with the Dendrometer. Therefore hold the device vertically in front of the eye (opening on top) and aim at the tree to be measured. Adjust the distance of the Dendrometer from the eye or your distance from the tree until the points k and h correspond to the tree tip resp. to the bottom of the trunk. The relation of the section hi to line hk is 1:10. the height of point i corresponds to 1/10 of the tree height. In order to calculate the tree’s height measure the distance from i on the tree to the tree base and multiply by 10. It should be considered that the measurement of tree heights is just a "side function" of this device, while the main purpose is in estimation basal area.
Estimation of basal area per hectare
The estimation of basal area is based on the principle of relascope sampling invented by Walter Bitterlich (Bitterlich 1952[3]). Aim at the dbh of each tree in a 360° sweep (from your standpoint). The basal area is a function of the angle and the number of stems which appear wider than the respective angle opening. Trees with width smaller than fg are not included in the sample (counted). If you hold the dendrometer vertically at a distance of 50 cm before the eye r (distance to the eye is fixed with rs is 50 cm), then the plate with the width 1 creates an angle for which every counted tree corresponds to 1 m² basal area per hectare (basal area factor = 1).
When a width of 2 or 4 is used, the resulting basal area (number of trees counted) must be multiplied by the corresponding factor (2 or 4) in order to obtain estimates of basal area per hectare. With relascope sampling on slopes it is necessary to multiply the estimated basal area per hectare with the coefficient k (k=1/cos α) for the respective maximal inclination of slope from the table on the Dendrometer.
Determining value of single trees by estimating volume sections
Set up the dendrometer in the same way as for height measurement. Through the markings b, c, d the stem is divided to 4 sections of equal volume.
Estimating stem volume with "form height"
For the 4 main tree species in northern Germany (Ei, Bu, Fi, Ki) and a given or measured mean stand height (hm) the "form-height factor" (FH-Tarif) can be read off the table on the dendrometer. Calculate stand volume per hectare in m³ including bark with the formula \(V=G*FH \,\).
References
- ↑ Kramer, H. 1990. Nutzungsplanung in der Forsteinrichtung. 2., überarbeitete und erweiterte Auflage. J.D. Sauerländer’s Verlag, Frankfurt/Main.
- ↑ Akca, A. 2001. Waldinventur. J.D. Sauerländer's Verlag. Frankfurt am Main, 193 S.
- ↑ BITTERLICH, W., 1952. Die Winkelzählprobe. Forstwissenschaftliches Centralblatt, 215-225.
