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<PRE>This was the appeal sent out to potential members to join
       the email discussion groups mentioned below:
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To all members of the band_dendrometry email discussion group
and various others who may be interested in the following:

I am iniating two discussion groups on the topics:
Automated electronic SOIL WATER CONTENT SENSORS and
LENGTH MONITORING SENSORS (for tree stem diameters for example).
These are summarised below.

(Please forgive this canvassing message if you are not
interested.)

Bruce Metelerkamp
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CS615 SOIL WATER CONTENT SENSORS         (SoWaCS group)
There has been a growing need for an accurate but
inexpensive automated soil water content sensor that is durable and
works over the complete wet to dry range.

I have tried various sensors for use with continuous datalogged
systems, but these did not have the required range and/or ruggedness.
Gypsum blocks are the worst, followed closely by nylon blocks,
Watermark sensors and heat dissipation sensors. I have not
yet tried paired needle heat pulse methods, nor the
"capacitance" methods. (I do not know what the latter
entails).

The promise of Time Domain Reflectometry (TDR) was limited by the
electronics required to use it, but a new TDR-like probe,
the CS615 sensor, seems to have overcome these problems.
It can be hooked up directly to a datalogger (all the Campbell
Scientific Incorporated models, anyway).

I am currently corresponding with a number of users and
other potential users to assess the sensor, which at less
than US$250, seems to be set to take the world.
Please contact me if you would like to join the email
discussion group on this and related sensors.

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AUTOMATED TREE STEM (DBH) MEASUREMENTS (and other
length-changing applications).                    (RR group)
Automated measurements of tree stem diameters have evolved
through from dial gauge dendrometers, LVDT systems, to
capacitance-based sensors, the latest of which is called the
Rubbery Ruler (RR). </PRE><A HREF="RR.html">RR homepage</A><PRE>
This relatively robust, cheap and small sensor operates on a
low voltage and returns a frequency proportional to its
"stretch". It is independant of temperature, and can be
logged with a good quality logger.

I am looking into getting dedicated microprocessors to
function as independant loggers thus reducing the logger
and extension wire requirements.

I have already run a sucessful discussion group on
manually-read band dendrometers, and now want to expand
this to the automated systems available: (see the
correspondance on my band_dendrometer homepage at
URL http://www.icfrnet.unp,ac.za/sowacs/band_dendrometry ).

If you would like to join one or both of these discussion
groups please contact me.

Heres to good measuring - and quality data!
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.
Bruce Metelerkamp           SOIL WATER RESEARCH OFFICER
Institute for Commercial Forestry Research,
University of Natal, PO Box 100281
Scottsville, ZA3209
Rep. of South Africa             Voice:27 331 62314
E-mail: bruce@icfr.unp.ac.za       FAX:27 331 68905
URL     http://www.icfrnet.unp.ac.za/~metele
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