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Dendrometers
and Dendrographs
An
excellent place to begin your tutorial about dendrometer bands is this
excellent web site titled "Construction
and Installation of Dendrometer Bands for Periodic Tree-Growth
Measurements,"
by Bobby D. Keeland and Patricia Joy Young through the U.S. Geological
Survey.
Band
dendrometers have long been used to monitor and record the growth of trees
on practically all time scales, from hourly to annually. The principle
here is to gain a better understanding of the interactions between
physiological and environmental mechanisms, so that we can better
understand to which environmental factors the trees are generally
responding. For example, did we notice that growth became enhanced during
an especially cool week? Perhaps tree growth is more related to edaphic
(soil) conditions than to actual rainfall amounts.
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Dendrometers
are usually bands that encircle the tree with some type of measurements
indicated and either manual or automatic recording devices. They are very
sensitive, and they can be very expensive. Dendrographs are similar, but
they also provide a visual record of the tree growth over time via graph
paper attached to a rotating drum. Modern instruments are sometimes
attached to real-time data loggers, such that we can have actual hard data
to input into spreadsheets or statistical packages for more detailed
analyses.
Agricultural
Electronics Corporation specializes in the design and implementation of
recording dendrographs and dendrometers. Founded by Bill Gensler, this
company has been working with various members of the Laboratory of
Tree-Ring Research in Tucson Arizona to measure various aspects of tree
growth and electrochemistry throughout the growing season. They can be
reached at:
Agricultural
Electronics Corporation
P.O. Box 50291
Tucson, AZ 85703-1291 USA
520-624-7656
520-624-9720 (fax)
Hans-Peter
Kahle and his colleagues in Freiburg, Germany, have used band dendrometers
and describes their set up: "The dendrometers we use are linear
variable displacement transducer sensors. The sensor for itself is a
commercial product. The aluminium cubes, holder plates (ca. 15 cm x 8 cm)
and screws are manufactured by our technician. The maximum displacement
way of the sensor type we use is +/- 2.54 mm, the error of nonlinearity
amounts to +/- 0.3 % (the more expensive type) to 0.5 % (the type we use)
of the total displacement. There is no hysteresis effect in the sensor
signal. The temperature range of the sensor is - 54° C to + 60° C, and
the temperature error related to sensor sensitivity is + 0.1. The sensors
are produced in the US (Trans Tek, if I remember right). The price per
unit is approx. 350 US Dollar (September 1997). Our sales company is:
Burster
Praezisionsmesstechnik GMBH
Talstrasse 1-7
D-76593 Gernsbach
GERMANY
+49-7224-6450
fax +49-7224-64588
info@burster.de
Matthias
Dobbertin at the Swiss Federal Institute of Forestry Research provided
information on two European suppliers of band dendrometers:
DIAL DENDRO
UMS-electronic: A compound of the
dendrometer DIAL-DENDRO (FOB Salzburg) with a compact sized electrical
sensor with automatic acquisition of data. The "tape" is an
invar steel cable with extremely low dependence on temperature; it is
gliding on a Teflon-net around the bark of the stem to reduce friction and
to protect against icing, resin and callousing - suitable for trees from
15 up to 120 cm diameter; the accuracy of measurement of the variation of
trees circumference is 0.01mm. The instrument is fixed at the tree with 2
stainless screws; it is advisable to use a drill for preparing the holes
for the screws for to reduce their influence on the tree. These are
compatible with datalogger, field-bus, handheld or PC data acquisition
boards, and time for adaption of the tape is about 6 - 8 weeks, shorter
when installing during the winter (dormancy) period. Their address is:
Mr. Gast
UMS
GmbH
Linprunstr. 42
D-80335 Muenchen
GERMANY
Tel: 089/182824
Fax: 089/182829
D6
Strain-Gauge Dendrometer: A
recent developed instrument for continuous high-resolution and automated
measuring of circumferencial variation of trees, by using electrical
signals caused by resistance change on a thin metal strip used as a
flexure device. Uses invar steel cable with extremely low dependence on
temperature, gliding on a Teflon-net around the bark of the stem to reduce
friction and to protect against icing, resin and callousing. Has easy
mounting without screws or other fixings, and is applicable on trunks as
well as on branches with small diameter. The accuracy of measurement of
the variation of trees circumference is 0.005 mm, and is compatible with
datalogger, field-bus, handheld or PC data acquisition boards.
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I
have installed both types of dendrometer bands in 1997 on one of our study
plots and connected them to a CR-10 logger from Cambell Co. The results so
far are very promising for the hourly readings with the strain gauge based
dendrometer. The DIAL-DENDRO, on the other hand, records the daily stem
expansion well, but reacts slow or not at all to daily stem shrinkage. So
if you are very interested in daily changes the D6 would be your choice.
The D6 has the other advantage that it needs not to be screwed into the
tree stem. It can, however, only record changes up to 2 cm circumference
changes before needing adjustment. Prices a piece are now by 622,- DM for
the DIAL-DENDRO and 542,- for the D6 Strain Gauge. However, if you order
more you will get a discount.
Dr.
Limin Xiong described how he used a "dendrometer band produced at the
University of Melbourne. You could contact them to obtain more
information. I have used their electric bands and a datalogger to collect
data from Libocedrus bidwillii during my PhD study with Dr. J.
Palmer in New Zealand."
Alberto Cimmino
School of Physics
University of Melbourne
Parkville, Victoria
3052, Australia
61-3-9344 5447
Fax: 61-3-9347 4783
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Regarding
development of band dendrometers, Kari Mielikainen of the Finish Forest
Research Institute METLA writes: "Referring to the discussion about
girth bands I have the pleasure to inform you that our team has developed
a girth band financed partly by the EU (pilot project). A couple of weeks
ago we sent our annual report to Brussels. Hoping to find some individuals
willing to read our 8-page paper we want to send the text to everyone
interested in the use of girth bands. (Matthias Dobbertin writes "It
is a girth band and has been tested for at least 2 years. Uses also a
rotating potentiometer. Supposedly measures changes down to 0.03 mm. Needs
only 1 nail to attach the band. The temperature expansion factor, however,
seems to be 10 times the one for the Dial-Dendro and you may have to
adjust for temperature changes. Price between $250 and 300.) Please, send
your address (postal and fax) to me by e-mail."
Investigators who have
used or are currently using either dendrometers or dendrographs include:
- Chris H. Baisan,
Laboratory of Tree-Ring Research, The University of Arizona, Tucson AZ
85721 USA
- Marco Carrer,
Universita degli Studi di Padova, Dipartimento Territorio e Sistemi
Agroforestali, Agripolis, I-35020 Legnaro (PD), ITALY
- Bernhard Denneler,
Groupe de recherche en ecologie forestiere inter-universitaire,
Universite du Quebec a Montreal, Montreal (Que.), Canada
- Matthias Dobbertin,
Swiss Federal Institute of Forestry Research, Zurcherstrasse 111,
CH-8903 Birmensdorf ZH, SWITZERLAND
- Harold C. Fritts,
Laboratory of Tree-Ring Research, The University of Arizona, Tucson AZ
85721 USA
- Hans-Peter Kahle,
Institut für Waldwachstum, Bertoldstr. 17, D-79085 Freiburg, Germany,
+49-761-2033739, fax: +49-761-2033740
- Bob Keeland,
USGS, National Wetlands Research Center, Lafayette, LA 70506 USA
- Limin Xiong, Wood
Quality Laboratory, Wood Technology Division, Forestry and Forest
Products Research Institute, Tsukubam, 305 JAPAN, +81 (298) 73 3211
extn. 575, +81 (298) 73 3798 (fax)
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