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United States Department of Agriculture

Agricultural Research Service

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 CO2 tank PHACE site
The PHACE project uses liquid CO2, stored in a 100,000 gallon refrigerated tank located near the field trailer.

The PHACE trailer houses the electronics for the CO2 control system and the dataloging computer. 

 Control valves anemometer
A series of computer controlled valves injects CO2 to 10 elevated plots based on feedbacks of plot CO2 concentration and wind speed.

A sonic anemometer relays wind-speed data to the CO2 control system.

 control system plastic flange

Inside of the PHACE trailer with CO2 control system on the wall.

 Each of the 30 PHACE plots is isolated from the off-plot soil with a heavy plastic flange buried to 60 cm.
 below ground barrier trencher
 The thick plastic flange prevents water and roots from entering or leaving the actual plot below-ground area.
 A line trencher was used to dig a hexagon shaped trench around all 30 plots, for the plot-soil-isolation flange.
 soil water sensor minirhizotron tube
 Each of the 30 PHACE plots has a soil water profile (Sentek) sensor installed to 80cm depth which constantly records volumetric water content.  Each of the 30 PHACE plots has a minirhizotron tube installed at 25o and to ~52cm depth. The minirhizotron camera takes photographs of roots at ~1cm depth intervals.
 RootTracker auger to install tubes
 RootTracker software is used to measure root lengths, widths and branching. Installing minirhizotron tubes using a large auger, power drill and custom angle brace.
 dataloggers CO2 pipes
 Plot soil water content, air and soil temperature are continually recorded using dataloggers and multiplexers. 10 plots are injected with pure  CO2 through a pipe lined with laser-drilled holes to 600ppm. An infra-red gas analyzer constantly monitors CO2 concentration at the center of the plot and sends this data to the CO2 control system in the field trailer.
 infra-red gas analyzers heaters
 The infra-red gas analyzers are mounted near the elevated CO2 plots. All wires and cables are housed in PVC conduit for protection from weather and animals.  10 of the PHACE plots are warmed 1.5oC during the day and 3oC at night using 6 infra-red heaters mounted above the plots.
 infra-red radiometer temperature controls
 Warming is controlled by measuring plot temperature with an infra-red radiometer and constantly relaying this data to a computer controlled PID feedback system.  The plot warming control system uses the infra-red radiometer inputs from control-temperature plots to vary the electrical current level to the IR heaters on the warmed plots.
 heaters  plot platforms
 A close-up of one of the 6 infra-red heaters that surround the warmed plots. To avoid damaging vegetation and sensors, plots are accessed from platforms which do not touch the plot area.
 watering plot infrastructure
 10 of the 30 PHACE plots are treated with either a deep-spring supplemental watering or frequent shallow-irrigations through the growing season. Water has to be trucked from a nearby water source.  Control CO2 and control temperature plots have the same 'infrastructure' as elevated CO2 and warmed plots to compensate for unintended effects of infrastructure.
 winter heating clipping crew
 Warming treatment plots are warmed year round, even during the winter.  Summer vegetation harvest, clipping crew must sit on planks in order not to smash the plot.
 2008 Harvest Crew A view from above heated plot
 Measuring weed responses to elevated CO2 and temperature Platforms prevent damage to the PHACE plants
 A warmed, ambient CO2 plot Collecting trace gace samples on the PHACE plots
 Using the minirhizotron camera to take photographs of roots June vegetation 2008
 Jack Morgan gives a presentation at the Global Change in Western Rangelands symposium, September, 2008 in Cheyenne, WY. PHACE site field tour for the Global Change in Western Rangelands symposium.
 Participants of the Global Change in Western Rangelands symposium visit PHACE plots. Dr. Dana Blumenthal discusses invasive weed research at the Global Change in Western Rangelands symposium PHACE tour.
 Dr. Jack Morgan discusses ecology research at the Global Change in Western Rangelands symposium PHACE tour. Dan LeCain and David Smith discuss the CO2 and Warming systems at the Global Change in Western Rangelands symposium PHACE tour.
 Participants of the 41st Annual Air Pollution Workshop tour the PHACE site with Dan LeCain in April, 2009. CSU graduate students tour the PHACE project in September 2012


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Last Modified: 8/12/2016
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