This data set reports stable isotope ratio data of CO2 (13C/12C and 18O/16O) associated with photosynthetic and respiratory exchanges across the biosphere-atmosphere boundary. Measurements were made at selected AmeriFlux sites: Harvard Forest, Howland Forest, Rannells Flint Hills Prairie, Niwot Ridge Forest, and the Wind River Canopy Crane Site, which span the dominant ecosystem types of the United States. These data were collected periodically from 2001 through 2004 and are available as an ASCII comma separated file.
The goal of this Terrestrial Carbon Processes (TCP) project is to better capture isotopic effects of ecosystem-atmosphere interaction at diurnal, seasonal and interannual time scales by long-term monitoring 13C of CO2 exchange with the atmosphere at weekly intervals. Photosynthesis and respiration in terrestrial ecosystems have opposite effects on diurnal and seasonal patterns on atmospheric CO2 concentration and isotope ratios. This isotopic variation contains information about the functioning of different terrestrial ecosystems.
Specifically, this research addresses the
following fundamental questions to meet the
need to have a stronger characterization of the isotopic composition of
CO2 in terrestrial biosphere-atmosphere exchange identified by the U.S.
Carbon Cycle Science Plan (CCWG, 1999):
This TCP project contributes to The Biosphere - Atmosphere Stable Isotope Network (BASIN) (http://basinisotopes.org), an umbrella program aimed at improving our understanding of carbon and water cycle processes at the ecosystem, regional, and global scales. Data sharing and integration will allow for cross-site comparisons and provide an opportunity to assess any continental or global effects.
Additional information about AmeriFlux and the measurement sites can be obtained from the program web site at http://ameriflux.lbl.gov/SitePages/Home.aspx.
Site Supplemental Information
A table of measurement sites cross referenced to FLUXNET sites and linked to the FLUXNET web site with supplemental information is included in Section 5.
Acknowledgement: The Terrestrial Carbon Processes (TCP) Program research performed by the Ehlringer Lab at the University of Utah, James Ehlringer, Director, was supported by the Office of Science (BER), U.S. Department of Energy, under Grant No. DE-FG03-00ER63012.
Cite this data set as follows:
Ehleringer, J.R. and C.T. Lai. 2010. BASIN TCP Stable Isotope Composition of CO2 in Terrestrial Ecosystems. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi: 10.3334/ORNLDAAC/963
This data set reports stable isotope ratio data of CO2 (13C/12C and 18O/16O) associated with photosynthetic and respiratory exchanges across the biosphere-atmosphere boundary. Measurements were made at selected AmeriFlux sites: Harvard Forest, Howland Forest, Rannells Flint Hills Prairie, Niwot Ridge Forest, and Wind River Canopy Crane Site, which span the dominant ecosystem types of the United States. These data were collected periodically from 2001 through 2004 and are available as an ASCII comma separated file.
These data were collected periodically from 2001 through 2004 and are available as an ASCII comma separated file.
Data file description : TCP_2001_2004_20091117.csv
| Column Heading | Units or format | Description | Method |
|---|---|---|---|
| TCP_site | character | Sampling site name | |
| TCP_location | character | Sampling location within site | |
| Date_sampled | mm/dd/yyyy | Date sample collected | |
| Time_sampled | hh:mm | Time sample collected. Missing code = -9999. | |
| Time_zone | character | Local standard time zone | |
| TCP_Contact | character | Sampling and analysis information contact | |
| Sample_type | character | Sampled medium is air. When TCP_source = 2001-2004: daytime, nighttime, or tank air may be specified. When TCP_source= TCP_2004: only air is specified. |
Sample_type = "tank air" indicates a calibration run and data values should not be combined with ambient samples. |
| Sample_ID | character | Data provider designation. Missing code = "Not provided" | |
| Flask_position | numeric | Sampling Strategies:
Intial approach - Flask 1: control flask Flask 2-3: mid-afternoon samples from level 3 (top of the canopy) Flask 4-15: nightime samples beginning an hour after sunset from level 1 and 2 (inside the canopy) Beginning in July 2003, four flasks are collected in the mid-afternoon. See Lai et al. (2003; 2004) for more information on sampling strategy. Missing code = -999. |
Flasks were collected by an automated sampling system (Schauer et al. 2003). |
| Height | meters | Sampling height in meters. Missing code = -999. | |
| CO2_air | ppm | CO2 concentration in flask sample.WMO scale. Missing code = -999.99 | Measured with a bellow/IRGA system (Bowling et al. 2001). |
| del_13C_CO2 | per mil | Isotopic ratio of 13C/12C in carbon dioxide. Pee Dee Belemnite (PDB) standard. Missing code = -999.99 | Flasks were analyzed for isotope ratios at the Stable Isotope Ratio Facility for Environmental Research (SIRFER) at the University of Utah using a continuous-flow isotope ratio mass spectrometer system (Precon attached to a Delta S, San Jose , CA.) |
| del_13_standard | character | VPDB scale | |
| del_18O_CO2 | per mil |
Isotopie ratio of 18O/16O
in carbon dioxide. Standard Mean Ocean Water (SMOW)
standard. Missing code = -999.99 |
Flasks were analyzed for isotope ratios at the Stable Isotope Ratio Facility for Environmental Research (SIRFER) at the University of Utah using a continuous-flow isotope ratio mass spectrometer system (Precon attached to a Delta S, San Jose , CA.) |
| del_18O_std | character | VSMOW scale | |
| TCP_source | character | Marker for data provider source | |
| Orig_TCP_data_file | character | Original data file name as received from provider. | Numerous data files were combined by the Data Center into this single file and checked for consistency. |
| Notes | character | Supplemental sampling and analysis information | If the Notesvalue is "bad point" or "questionable" then related data values have been set to missing. |
| Ecosystem | character | Data provider designation | |
| Species | character | Data provider designation. | |
| Data_source1 | character | Data provider information. | |
| Data_source2 | character | Data provider information. |
Example data records:
| TCP_site,TCP_location,Date_sampled,Time_sampled,Time_zone,TCP_Contact,Sample_type,Sample_ID,Flask_position,Height, CO2_air,del_13C_CO2,del_13C_std,del_18O_CO2,del_18O_std,TCP_source,Orig_TCP_data_file,Notes,Ecosystem,Species, Data_source1,Data_source2 character,character,mm/dd/yyyy,hh:mm,character,character,character,character,numeric,meters, ppm,per mil,character,per mil,character,character,character,character,character,character, character,character ... Harvard Forest,EMS Annex Walk-Up Tower (130m SW of the EMS eddy flux tower),23/08/2001,20:52,EST, "Chun Ta Lai, Jim Ehleringer",tank air,A131 (15),15,-999,396.00,-30.18,PDB,2.29,SMOW,2001-2004, 01_08_HV_auto_2.xls,,broadleaf forest,"Quercus velutina, Acer rubrum",DOE/TCP project - Stable Isotope Analyses at the Harvard Forest Harvard Forest,EMS Annex Walk-Up Tower (130m SW of the EMS eddy flux tower),23/08/2001,15:24,EST, "Chun Ta Lai, Jim Ehleringer",daytime air,5E (1),1,22.4,370.40,-8.19,PDB,40.62,SMOW,2001-2004, 01_08_HV_auto_2.xls,,broadleaf forest,"Quercus velutina, Acer rubrum",DOE/TCP project - Stable Isotope Analyses at the Harvard Forest ... Wind River,Crane,10/09/2004,19:42,PST,"Chun Ta Lai, Jim Ehleringer",air,AAA4.5,5,0.5, 494.55,-12.83,PDB,39.06,SMOW,TCP_2004,040915_WR_auto_1.xls,,conifer forest,Pseudotsuga menziesii, DOE/TCP project, Wind River,Crane,10/09/2004,19:47,PST,"Chun Ta Lai, Jim Ehleringer",air,A20.6,6,30, 413.02,-10.21,PDB,40.43,SMOW,TCP_2004,040915_WR_auto_1.xls,,conifer forest,Pseudotsuga menziesii, DOE/TCP project, Please note that line breaks were added to improve readability and are not in the data file. |
Site boundaries: (All latitude and longitude given in decimal degrees)
| Site (Region) | Westernmost Longitude | Easternmost Longitude | Northernmost Latitude | Southernmost Latitude | Geodetic Datum |
|---|---|---|---|---|---|
| Howland Forest (Main Tower), ME USA | -68.740278 | -68.740278 | 45.2040700 | 45.2040700 | World Geodetic System, 1984 (WGS-84) |
| Harvard Forest EMS Tower (HFR1), MA USA | -72.171478 | -72.171478 | 42.5377556 | 42.5377556 | World Geodetic System, 1984 (WGS-84) |
| Niwot Ridge (LTER NWT1), CO USA | -105.546403 | -105.546403 | 40.0328778 | 40.0328778 | World Geodetic System, 1984 (WGS-84) |
| Niwot Ridge (LTER NWT2), CO USA | -105.546944 | -105.546944 | 40.0325000 | 40.0325000 | World Geodetic System, 1984 (WGS-84) |
| Rannells Ranch (ungrazed), KS USA | -96.523000 | -96.523000 | 39.1390000 | 39.1390000 | World Geodetic System, 1984 (WGS-84) |
| Wind River Crane Site, WA USA | -121.9519111 | -121.9519111 | 45.8204889 | 45.8204889 | World Geodetic System, 1984 (WGS-84) |
Time period:
Stable isotope ratios of CO2 are recognized as a key element in improving our interpretations of the carbon cycle at the ecosystem, regional, and global scales. The 13C and 18O analyses of CO2 have been an element of the NOAA Cooperative Air Sampling Network - global flask network (http://www.esrl.noaa.gov/gmd/ccgg/flask.html) for over a decade, where these data are essential in partitioning fluxes within the global carbon cycle. The global flask network is an international effort which includes regular discrete samples from the 4 NOAA ESRL/GMD baseline observatories, cooperative fixed sites, and commercial ships. Air samples are collected approximately weekly from a globally distributed network of sites.
Stable isotope analyses are now becoming integrated into regional and ecosystem carbon cycle studies. In part this lag has been because terrestrial surfaces can have large diurnal, vertical, and seasonal impacts on CO2 concentration and isotope ratios. Much of this variation is filtered out in a flask network that is largely focused at marine sampling sites. The U.S. Carbon Cycle Science Plan (1999) recognizes the need to expand atmospheric monitoring over terrestrial surfaces and the need to have a stronger characterization of the isotopic composition of CO2 in terrestrial biosphere-atmosphere exchange. In that regard, the Terrestrial Carbon Processes (TCP) Program specifically identifies the need to "... obtain isotopic data that pinpoints source and seasonality of CO2 fluxes". This project directly addresses the isotope ratio needs identified by both the U.S. Carbon Cycle Science Plan and the TCP Program.
Measurement values flagged as questionable or bad by the data provider were set to missing, but the Note indicating a problem may remain. Quality assurance of the samples collected manually and by the automated sampling system are discussed in Schauer et al. (2003).
Flasks were collected by an automated sampling system (Schauer et al. 2003) for analyses of concentration, 13C and 18O ratios of carbon dioxide at AmeriFlux sites, including Wind River Canopy Crane Research Facility, Washington, Rannells Flint Hills Prairie, Kansas, Harvard Forest, Massachusetts, and Howland Forest, Maine.
Flasks were analyzed for isotope ratios at the Stable Isotope Ratio Facility for Environmental Research (SIRFER) at the University of Utah using a continuous-flow isotope ratio mass spectrometer system (Precon attached to a Delta S, San Jose, CA). Concentrations of carbon dioxide were measured with a bellow/IRGA system (Bowling et al. 2001). Beginning in April 2004, both concentration and isotope ratios were measured by an automated GC-IRMS system (Schauer et al. 2004).
Site with Supplemental Information
TCP site names cross referenced to FLUXNET site names and linked to FLUXNET web site with supplemental information.
| TCP Site | TCP Location | FLUX_site_name | IGBP_class | Latitude | Longitude | Elev | State | FLUX_ network | FLUX_site_link |
|---|---|---|---|---|---|---|---|---|---|
| Wind River | Crane | Wind River Crane Site | Evergreen needleleaf forest | 45.8204889 | -121.95191 | 355 | WA | AmeriFlux | http://www.fluxnet.ornl.gov/site/1103 |
| Wind River | Young Stand | Evergreen needleleaf forest | WA | ||||||
| Niwot Ridge | East | Niwot Ridge Forest-Colorado (LTER NWT1) | Evergreen needleleaf forest | 40.0328778 | -105.5464 | -999 | CO | AmeriFlux | http://www.fluxnet.ornl.gov/site/997 |
| Niwot Ridge | West | Niwot Ridge Forest (2)-Colorado (LTER NWT2) | Evergreen needleleaf forest | 40.0325 | -105.54694 | -999 | CO | Unaffiliated | http://www.fluxnet.ornl.gov/site/998 |
| Rannells Flint Hills Prairie | Ungrazed Site | Rannells Ranch (ungrazed) | Grasslands | 39.13900 | -96.52300 | -999 | KS | Unaffiliated | http://www.fluxnet.ornl.gov/site/920 |
| Howland Forest | Main Tower | Howland Forest Main Tower | Mixed forest | 45.20407 | -68.740278 | 60 | ME | AmeriFlux | http://www.fluxnet.ornl.gov/site/890 |
| Harvard Forest | EMS Annex Walk-Up Tower EMS (130m SW of the eddy flux tower) |
Harvard Forest EMS Tower (HFR1) | Mixed forest | 42.5377556 | -72.171478 | 340 | MA | AmeriFlux | http://www.fluxnet.ornl.gov/site/886 |
These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC) [http://daac.ornl.gov].
E-mail: uso@daac.ornl.gov
Telephone: +1 (865) 241-3952
Bowling DR, Cook CS, Ehleringer JR (2001)
Technique to measure CO2 mixing ratio in small flasks with a
bellows/IRGA system. Agricultural and Forest Meteorology, 109, 61-65. doi:10.1016/S0168-1923(01)00252-0
CCWG, 1999. A U.S. Carbon Cycle Science Plan. Sarmiento, J.L. and S.C. Wofsy (eds.). Carbon and Climate Working Group, University Corporation for Atmospheric Research, Washington, DC, USA, 69 pp.
Lai CT, Schauer AJ, Owensby C, Ham JM, and
Ehleringer JR (2003)
Isotopic Air Sampling in a Tallgrass Prairie to Partition Net Ecosystem
CO2 Exchange, Journal of Geophysical Research, 108, D18(4566),
doi:10.1029/2002JD003369.
Lai C-T, Ehleringer JR, Tans PP, Wofsy SC, Urbanski SP, Hollinger DY
(2004) Estimating photosynthetic 13C discrimination in terrestrial CO2
exchange from canopy to regional scales, Global Biogeochemical Cycles,
18, GB1041, doi:10.1029/2003GB002148.
Schauer AJ, Lai C-T, Bowling DR, and Ehleringer JR (2003) An automated
sampler for collection of atmospheric trace gas samples for stable
isotope analyses. Agricultural and Forest Meteorology, 118, 113-124. doi:10.1016/S0168-1923(03)00065-0
Schauer AJ, Cook C, Lott M, Ehleringer JR (2004) An automated system
for stable isotope and concentration analyses of CO2 from small
atmospheric samples, submitted to Rapid Communications in Mass
Spectrometry.