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The terracosm facility has 12 chambers, with four replicates per temperature treatment.
Ambient environmental conditions are monitored by a weather station (background, left). Temperature, relative humidity, and CO2 concentrations are adjusted continuously in the terracosms based on ambient conditions.
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"Door-open days" occur every two weeks and are our
opportunity to open the terracosms for a few hours to perform routine
measurements, instrument calibrations, and troubleshooting.
The rest of the time door openings are severely restricted, which
allows us to meet target levels for meteorological variables over 95%
of the time.
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Some of the automated features of the terracosms include
(1) Hourly soil CO2 efflux measurements
(2) Rain collection and real-time irrigation
(3) Automatic door opening, which allows in freezing conditions and permits frost formation. Automatic door opening also provides a safety mechanism to quickly restore humidity, temperature, and CO2 levels if terracosms exceed allowed tolerances.
In addition, the entire chamber acts as a cuvette, allowing automated hourly measurement of CO2 exchange rate
Evapotranspiration, soil moisture, and deep leachate are also continuously monitored, allowing for complete accounting of the water budget.
(photosynthesis and respiration).
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One on the unique and important features of the terracosms is that they
enclose the belowground environment. The terracosms extend belowground
1m and are thermally insulated from the surrounding soil, allowing
air temperature manipulations to propagate belowground.
The
soil profile was reconstructed from a local grassland in 20cm depth
increments. It is instrumented at five depths with temperature and
moisture sensors, gas wells for collecting CO2 and other gases, and minirhizotron tubes for monitoring root growth.
The terracosms also act as a large lysimeter: water that percolates
through the soil is collected at the bottom, and analyzed for organic
carbon and nutrient concentrations.
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Here in command central, the terracosms are controlled using RSView
logic. Alarm calls allow us to detect and quickly respond to any
problems that arise.
By logging in remotely we can (and do) access the terracosm controls 24 hours a day, from anywhere!
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