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Oak Ridge National Laboratory (ORNL) FACE

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aerial view of Oak Ridge FACE site

Oak Ridge FACE

Supported by the U.S. Department of Energy, the Oak Ridge Free-Air CO₂ Enrichment (FACE) experiment studied how forests respond to shifting levels of carbon dioxide (CO₂) in the atmosphere. 

Located at Oak Ridge National Laboratory in Tennessee, this long-term project focused on a closed-canopy sweetgum (Liquidambar styraciflua) forest to test how future CO₂ conditions could impact forest growth and ecosystem health. 

While previous studies have examined small trees or individual processes, ORNL FACE observed the integrated response of an intact forest, capturing how trees, soil, and atmosphere interact at the ecosystem level. 

 

Research

By studying how an entire forest stand functions as a system rather than isolated parts, the ORNL FACE experiment sought to understand how the eastern deciduous forest will be affected by CO2 enrichment of the atmosphere. The project also sought to quantify the carbon feedback from the forest to the atmosphere.

Features

  • Facility: Five 25-meter experiment plots built within a deciduous forest plantation on the Oak Ridge Environmental research park.
  • Forest Type: The stand was a sweetgum (Liquidambar styraciflua) monoculture planted in 1988, about 18 meters tall with a fully closed canopy.
  • Key Characteristics:
    • A closed canopy limited individual tree growth, creating realistic competition for light.
    • Full root occupancy constrained nutrient cycling, offering insights into long-term soil changes.
    • The larger size of mature trees compared to seedlings altered carbon cycling dynamics.
    • The extended time frame allowed scientists to measure gradual changes in soil carbon and ecosystem processes.
View Site Characteristics

Data

The FACE data provided on this site are freely available and were furnished by individual FACE scientists who encourage their use. Please inform Rich Norby (Principal Investigator, ORNL FACE, rnorby@utk.edu) of how you are using these data and of any publication plans.

Riggs J ; Tharp M ; Norby R (2007): ORNL FACE Weather Data. CDIAC, ESS-DIVE repository. Dataset. https://doi.org/10.15485/1463817

  • Weather Data (1999-2010, gap-filled 1999-2008)
    • Air Temperature
    • PAR
    • Precipitation
    • Relative Humidity
    • Soil Temperature
    • Solar Irradiance
    • Wind Speed

Riggs J ; Tharp M ; Norby R (2007): ORNL FACE CO2 Concentration Data. CDIAC, ESS-DIVE repository. Dataset. https://doi.org/10.15485/1463842 

  • Carbon Dioxide Concentration Data (1999-2010, gap-filled 1999-2008)
    • Carbon Dioxide
    • Solar Angle
    • Wind Direction
    • Wind Speed

Norby R ; Tharp M (2007): ORNL FACE Leaf Area Index (LAI). CDIAC, ESS-DIVE repository. Dataset. https://doi.org/10.15485/1463810   

  • Lead Area Index (1999-2009)

Norby R ; Tharp M (2007): ORNL FACE Basal Area. CDIAC, ESS-DIVE repository. Dataset. https://doi.org/10.15485/1463816 

  • Tree Basal Area (1997-2007)

Ledford J ; Norby R ; Tharp M (2007): ORNL FACE Fine Root Data. CDIAC, ESS-DIVE repository. Dataset. https://doi.org/10.15485/1463811 

  • Fine Root Data (1998-2007)
    • Root Mortality
    • Root Production
    • Root Standing Crop

Norby R ; Iverson C ; Tharp M (2007): ORNL FACE Nitrogen Concentrations (Leaves, Litter, Fine Roots, Wood). CDIAC, ESS-DIVE repository. Dataset. https://doi.org/10.15485/1463845

  • Tree Nitrogen Concentrations (1998-2009)
    • Leaf Nitrogen
    • Litter Nitrogen
    • Fine Root Nitrogen
    • Wood Nitrogen

Norby R (2021): ORNL FACE Tree Height, with data on height of a subset of trees measured every year, 1997-2009. Free-Air CO2 Enrichment (FACE) Experiment Synthesis Activities. ORNL FACE Experiment, ESS-DIVE repository. Dataset. https://doi.org/10.15485/1798175

  • Tree Height (1997-2009)

Norby R ; Warren J ; Iversen C ; Childs J (2021): ORNL FACE Final Harvest, 2009, with data on leaf characteristics and tree mass. ORNL FACE Experiment, ESS-DIVE repository. Dataset. https://doi.org/10.15485/1779883 

  • Tree Destructive Harvest Data (2009)
    • Basal Area
    • Height
    • Leaf Mass Area
    • Leaf Mass Volume
    • Leaf Thickness
    • Total Aboveground Wood Mass
    • Total Leaf Mass

Tharp M ; Norby R (2007): ORNL FACE Soil Moisture Data. CDIAC, ESS-DIVE repository. Dataset. https://doi.org/10.15485/1463846   

  • Soil Moisture (1997-2008)