In 1990 a Campbell CR21x data logger, AM32 multiplexer (in a insulated enclosure) and sensors were installed in block 2 of the Moist Acidic Tundra (MAT1989) site at Arctic Long Term Ecological Research Site (ARC LTER) near Toolik Lake Field Station, Alaska to monitor the experimental plots - control (CT), greenhouse (GH), greenhouse plus nitrogen and phosphorus (GHNP) shade (SH), shade plus nitrogen and phosphorus (SHNP) and nitrogen and phosphorus (NP) plots.  The plots were setup in 1989 in a 4 block randomized plot design in moist acidic tussock tundra.

Two profiles of soil temperature are measured per treatment plot with copper/constantan thermocouple wires (TC) installed at depths of 10, 20, and 40 cm in inter-tussock areas. The sensors were initially installed on fiberglass poles that were installed into the frozen layer to 1.5 meters. The following label codes are used: CT = control, GH = greenhouses, SH = shade houses, NP = fertilized, GHNP= greenhouse fertilized, SHNP = shade house fertilized, plus a 1 or a 2 for the profile number.  All soil sensors are read every 15 minutes and averaged every 3 hours.  Meteorological data was also collected but is in a different dataset.   Meteorological sensors include: global solar radiation, photosynthetic active radiation, unfrozen precipitation, air temperature, relative humidity, wind speed, and wind direction at 3 meters.
 
The fertilizer treatments are applied every year in early June at the rate of 10 gram per meter nitrogen and 5 grams per meter as phosphorus using commercial grade fertilizers.  Until 2012 nitrogen was applied with 34-0-0 (34% nitrogen as ammonium nitrate).  After 2012  ammonium chloride and sodium nitrate products are used.  Phosphorus is applied with 0-45-0 (45% P2O5 =19.89%P). The greenhouse covers are removed every fall around 20 August and reinstalled every spring in early June.

NOTES:

--The original data are archived at The Marine Biological Lab, Woods Hole, MA.
--Soil temperatures are problematic since frost heaving of the probes caused depth of measurements to change. Despite having fiberglass poles installed into the frozen layer the poles were being frosted heaved changing the depth of the sensors. 

August 2002:

Canopy within and above temperatures were added for CT, GH, GHNP, NP and the nitrogen plus phosphorus animal exclosure (NPEX) treatment plot as well as soil depth profiles for the NPEX plot. 

The animal exclosure plots were setup in 1996 in extra plots within the 4 blocks.  Each plot included sections with unfenced, large and small mesh fences. In each block one plot was fertilized with 10 gram per meter square nitrogen and 5 grams per meter square  phosphorus (NPEX) and one unfertilized control plot (CTEX).  Temperature profiles were only measured in block 2 NPEX in the unfenced section. 

Canopy sensors were copper/constantan thermocouple wires installed in a Hobo RS1 radiation shield.  The shields were placed above the canopy or within.  For the control plots which has very low vegetation the within sensors were placed as close to the surface as possible.  At this time the AM32 was replaced with two AM416 multiplexers to accommodate more thermocouples.  Campbell Scientific AM ENCT thermally insulated multiplexer enclosures were used.

August 2012:

The soil sensors were taken off the poles and installed at depths horizontally in a soil pit.  The pit was cut using a knife and the peat carefully removed and replaced after the sensors were in stalled.  Extra wire was buried to help minimize any heating along the wire. An additional 20 cm soil sensor was added to CT, GH, GHNP, SH, SHNP, and NP plots.

The Campbell Scientific CR21X was replaced with a CR23X data logger.

Notes from Aug 11th:  Worked on resetting and rewiring the MAT plots.  Replaced the old blue wire TC (which was string 1 in each plot; string 2 was already Omega wire) with either the Campbell TC wire (NP1) or the Omega TC Wire.  Procedure was to trace back the pipe with the blue wire cutting the tape where the Omega wire was taped to the outside of the pipe.  Pulled the Omega wire back to the plot end of the pipe. This was difficult since the pipe and wire was overgrown in place to 10 - 20cms.  Then if all the wires were Omega TC the wires were taped to the blue wire and pulled back to the logger.  Before removing the blue wires and resetting string 2 the current depths of the wires were recorded.  The wires were then placed at 10, 20, 40 cm in the side of a pit cut to the frozen layer .  In most cases I was able to push the wire in about 5cm. But some 40 cm were at the ice layer so I was not able to get it into the side wall but laid it on the bottom of the hole.  The tundra was very wet so the hole filled fast.

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Sensor Description
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THERMOCOUPLES:
Campbell Scientific, 105E-L Type E Thermocouple Burial Probe

Omega Engineering, Copper-Constantan wire. Range -200 to 350 °C. Limits of error: Standard wire 1.0°C or 0.75% above 0°C and 1.0°C or 1.5% below 0°C. Special wire 0.5°C or 0.4%.

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List of manufactories and suppliers.

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Campbell Scientific, 815 W 1800 N, Logan, UT 84321-1784
Omega Engineering, Inc. P.O. Box 4047, Stamford, CT 06907-0047 (800)826-6342
Onset Computer Corporation, 470 MacArthur Blvd., Bourne, MA 02532