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The re-use of scientific data has the potential to greatly increase communication, collaboration and synthesis within and among disciplines, and thus is fostered, supported and encouraged. Permission to use this dataset is granted to the Data User free of charge subject to the following terms:

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Shaver, G. 1989. Above ground biomass in acidic tussock tundra experimental site, 1989, Arctic LTER, Toolik, Alaska. Arctic LTER, Marine Biological Lab, Woods Hole, Ma 02543. 1989gsttbm http://ecosystems.mbl.edu/arc/terrest/biomass/index.shtml 

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Data sets were provided by the Arctic LTER. This material is based upon work supported by the National Science Foundation under Grants #DEB-981022, 9211775, 8702328; #OPP-9911278, 9911681, 9732281, 9615411, 9615563, 9615942, 9615949, 9400722, 9415411, 9318529; #BSR 9019055, 8806635, 8507493.

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Dataset URLs:METADATA: HTML, Rich Text, XML(EML compliant)
DATA: Comma Delimited, Excel file with Metadata and data, Dataset via LTER Data Poral
Dataset ID:2012_GS_ITEX_PF_ShootACiData.06
Dataset Title:A/Ci curve parameters measured from shoots harvested at three levels in the canopy from 19 1m x 1m plots dominated by S. pulchra and B. nana shrubs near LTER Shrub plots at Toolik Field Station, AK the summer of 2012.
Investigator 1: 
First Name:Gaius
Last Name:Shaver
Organization:Ecosystems Center at the Marine Biological Laboratory
Address line 2:7 MBL Street
Address line 3:
City:Woods Hole
State:MA
Zip Code:02543
Country:United States
Investigator 2: 
First Name:Edward
Last Name:Rastetter
Organization:Ecosystems Center at the Marine Biological Laboratory
Address line 2:7 MBL Street
City:Woods Hole
State:MA
Zip Code:02543
Country:United States
Investigator 3: 
First Name:Mathew
Last Name:Williams
Organization:University of Edinburgh
Address line 2:School of Geosciences
City:Edinburgh
State:
Zip Code:EH9 EJU
Country:United Kingdom
Investigator 4: 
First Name:James
Last Name:Laundre
Organization:Ecosystems Center at the Marine Biological Laboratory
Address line 2:7 MBL Street
Address line 3:
City:Woods Hole
Zip Code:02543
Country:United States
Investigator 5: 
First Name:Laura
Last Name:van der Pol
Organization:Ecosystems Center at the Marine Biological Laboratory
Address line 2:7 MBL Street
City:Woods Hole
State:MA
Zip Code:02543
Country:United States
Associate Investigators:
Keywords:shoot photosynthesis; shrub canopy; point frame; A/Ci curve; electron transport, carboxylation efficiency
Abstract:A/Ci curve parameters and modeled carboxylation, electron transport, and triose-phosphate utilization efficiency rates from shoots clipped from low, mid, and the top of tall, shrub canopies dominated either by Salix pulchra or Betula nana species. Six shoots were harvested from each 1m x 1m plot, two from each level in the canopy. These plots were located near the LTER shrub plots at the Toolik Field Staion, AK for point frame measurements, and all measurements took place the summer of 2012. The species harvested were chosen based on the species present in each plot, thus the species from each segment of the canopy may not be the same. Additional information about each shoot can be found in the "PF_ShootLightcurve_Data" and "PF_ShootHarvest_Data" pages, regarding the light response curves, area, mass, leaf area index, and leaf nitrogen content of each shoot. The file "PF_PercentCover" contains the species cover data for each plot.
For questions about the Metadata and data contact the Investigators.
For information about this web site contact:
Arctic LTER Information Manager
The Ecosystems Center
Marine Biological Lab
7 MBL St
Woods Hole, MA 02543
Phone (508) 289 7496
Email: arc_im@mbl.edu
Online URL: http://ecosystems.mbl.edu/ARC/
DATA FILE INFORMATION:
Data File URL http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-arc.10144&urlTail=terrest/tracegas/data/2012_GS_ITEX_PF_ShootACiData.csv
Data File Name 2012_GS_ITEX_PF_ShootACiData
Beginning Date 6/23/2012
End Date 8/7/2012
Number of Data Records 115
Other Files to Reference 2012_GS_ITEX_BF3_DiffuseLightData; 012_GS_ITEX_CH_SoilData; 2012_GS_ITEX_CHFluxData; 2012_GS_ITEX_LC_ParameterSummary; 2012_GS_ITEX_MaxCanopyHeight; 2012_GS_ITEX_PercentCover; 2012_GS_ITEX_CHN_Data; 2012_GS_ITEX_PF_LAISummary; 2012_GS_ITEX_RawPinDrop_Data; 2012_GS_ITEX_ShootACiData; 2012_GS_ITEX_ShootHarvestData; 2012_GS_ITEX_ShrubCanopy_DailyLogger; 2012_GS_ITEX_InstantLogger; 2012_GS_ITEX_SunScan_LAI; 2012_GS_ITEX_SunScan_PAR; 2012_GS_PFandCH_GPS; 2012_GS_ITEX_PF_ShootLightCurve; 2003-2004gsfluxleafN; 2003-2009gscurveparameters; 2003-2009gsflux; 2003-2009gsGPSandveg; 2003-2009gsharvestLAI-N; 2003-2009gsspecieslist; 2004-2009gscoverft; 2004-2009gscoversp;
Availability Status 1
Quality Control Information
Maintenance Description This was a season-long project, though it followed similar methods to ITEX projects performed starting in 2003 that are likely to be replicated in the future for reasearch at the Toolik Field Station, AK.
Log of Changes: Version 2: Updated units to current standards. Missing values changed to #N/A. CH 28Jan2013
Version 3: Updated metadata to newer form (with sites sheet). CH April 2013.
Version 4: Corrected eml excel file name wrong extension. JimL 16May13
Version 5: Corrected the upper/lower case of missing value JimL 17May13
Version 6: Corrected Distrubution URL. It had xlsfiles in the path. Jim L 19Jun14
 
RESEARCH LOCATION:                  
Location Name LTER Shrub Block 1 LTER Shrub Block 2 Select Site or enter New One Select Site or enter New One Select Site or enter New One Select Site or enter New One Select Site or enter New One Select Site or enter New One  
Geographic Description Upland site; co-located in Block 1 of the Shrub LTER sites; IVO 68 38'18.8" N, 149 34' 07.2" W +/- 50m. Except for plots marked "FERT", plots are outside of the designated LTER treatments, though are exposed to the same environmental conditions. All plots were chosen by the dominant shrub canopy (either Salix pulchraor Betula nana) and preferentially selected to be 90cm+ in height. Outlet site; co-located in Block 2 of the Shrub LTER sites; IVO 68 38'008.1" N, 149 35' 017.1" W +/- 50m. Except for plots marked "FERT", plots are outside of the designated LTER treatments, though are exposed to the same environmental conditions. All plots were chosen by the dominant shrub canopy (either Salix pulchraor Betula nana) and preferentially selected to be 90cm+ in height. Enter Description Enter Description Enter Description Enter Description Enter Description Enter Description  
Location Bounding Box                  
West Bounding Coordinate                  
East Bounding Coordinate                  
North Bounding Coordinate                  
South Bounding Coordinate                  
OR if single point location                  
Latitude 68.6385555555555 68.6355833333333 In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees  
Longitude -149.568666666666 -149.588083333333 In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees  
Elevation 747 m 730 m In Meters In Meters In Meters In Meters In Meters In Meters  
Link to Google Map View on Google Map View on Google Map              
                   
 
TAXONOMIC COVERAGE:
Organisms studied Betula nana; Salix pulchra; Salix glauca
 
Methods:HARVEST METHOD:
The methods for setting up each point frame plot are described below in the section titled "POINT FRAME PIN-DROP METHODS". The methods here describe how each shoot was harvested from the plots which were used for the point frame method.

Six shoots were harvested from each of 19 1m x 1m point frame plots which were dominated either by Salix pulchra or Betula nana tall, shrub species. The "shoots" described here are branch clippings between eight to ten inches long. Whenever possible they were selected for appearing relatively healthy, intact leaves, and each shoot was taken from a different plant. As these shoots were used for shoot-level and leaf-level measurements, shoots with bi-furcated stems -- or two stems from the same branch/height were cut -- one for leaf-level and the second for shoot-level analyses.

Before being cut, we measured the distance from the point frame to the highest tip on the shoot as well as the distance from the point frame to the shoot five inches from the tip. This way, we could approximate the angle of the shoot relative to the ground. Using the same criteria as for the pin-drop measurements, we measured the distance from the top of the shoot to the soil. In addition, the row number and pin-hole number nearest to the shoot's location with respect to the point frame was also recorded .

We then measured the leaf area index (LAI) of the shoot by holding an LAI-2000 (Li-Cor Inc., Lincoln, Nebraska, USA) in the exact location where the shoot had been and taking the average of three readings (one above, three below). For these measurements we used the one-quarter cut out and took care to always hold the instrument level and with the technician's body casting a uniform shadow over the instrument's eye, with the technician standing between the instrument and the sun. On occasion when it was raining during the shoot harvest, the area near where the shoot had been was marked with flagging tape, and the the LAI measurement was taken at a later date, using the height from frame/distance from ground meausrements as well as the row number and pin hole measurements as a guide.

Once cut, the shoot was placed immediately into water and transported to the lab. Once in the lab, the end of each shoot was clipped under water to ensure that there were no air bubbles in the stem that would inhibit the flow of water. Shoots were then allowed to sit at ambient room conditions (~20-25 degrees Celsius) until the the photosynthetic rates could be measured.

A/Ci CURVE MEASUREMENT:

The A/Ci curve measurements were taken using a Licor 6400 photosynthesis system (Li-Cor Inc., Lincoln, Nebraska, USA) with an opaque conifer chamber with red-blue-green (RGB) light source attachment (model number 6400-22L). The methods for setting up the LI-6400 are detailed in the ITEX Manual as updated in 2011 as are the procedures for correcting and modeling the A/Ci data.

Each shoot was oriented in the chamber so that the leaves were facing the RGB light source. Care was taken to ensure that no leaves were caught between the foam gaskets. Aditionally, adhesive, mounting tack was used to ensure a seal around the end of the stem that protruded from the chamber and remained in water for the duration of measurements.

The A/Ci curve measurements were conducted with the reference light level set to a constant 1500 umol PAR m-2 s-1. Each shoot was allowed to acclimate to the chamber conditions for 5-10 minutes or until the Ca:Ci ([CO2]amb to [CO2]internal to the cell) ratio was stable around ~0.7 +/- 0.1. The A/Ci curve measurements were taken at the following target chamber CO2 concentrations in the order listed (units are umol CO2): 400, 300, 200, 100, 50, 400, 500, 700, 900, 1300, 1500, 1700, 400. The shoot was given a minimum of 60 seconds but not more than 180 seconds to adjust to each new CO2 concentration before a measurement was taken, and the instrument matched the reference and sample chambers prior to every measurement. The block temperature of the infra-red gas analyzer (IRGA) was adjusted throughout the A/Ci measurement to maintain a leaf temperature as near as possible to 20 degrees Celsius.

Once the measurment was complete, we took a light curve measurement, and then each shoot was carefully cut from the stem that remained outside the chamber so that only the portion of the shoot inside the chamber remained. This whole shoot was then photographed for later silhouette-area analysis with Image-J software [See "PF_ShootHarvest_Data" for details]. The leaves, stipules, petioles, green and brown stem, and other plant green organs were then clipped from the shoot, lain flat on a hinged, plexiglass folder, and scanned. These images were subsequently processed with the Image-J software to calculate the area of each tissue type; the sum of the area of the leaves, petioles, and stipules were used to correct the default area used when taking the light curve measurements.

Each tissue type was separated, placed in a coin envelope, labeled, and dried at 60 degrees Celsius at least three days before being weighed on a four-point balance with glass enclosure. The mass of each sample can be found in the "PF_ShootHarvest_Data" file.

CHN ANALYSIS:
Grinding: All leaf samples were dried in an oven at 60C before grinding. Samples were small enough to grind the entire sample without subsampling. Leaves were ground using the Retsch MM 200 for 3 minutes or until a talcum powder consistency was achieved.

Weighing: After grinding, samples were stored in glass scintillation vials and dried again at 60C for at least 36 hours. Once samples were removed, vials were tightly re-capped. When not in use, vials were stored in dessicators. 3.5-4.5 mg of each sample was weighed into a 10x12 mm tin capsule. A standard calibration curve was created using increasing amounts of aspartic acid (from about 0.2 mg to 5.0 mg). A chemical standard, acetanilide, and an organic sample, apple leaf, were run after the standard curve. Every ten samples, an aspartic acid check standard and a duplicate of an already-packed sample were run.

CN analysis: CN analysis was run between 10/4/2012 and 11/15/2012 by Rachel Rubin using the ThermoScientific 2000 at the Ecosystems Center, MBL, Woods Hole, MA. Duplicate sample values were averaged (mass, %N and %C) before inclusion into final results. The CHN data is available in the file "PF_CHN_Data".


CURVE MODELS:
Once corrected for the actual leaf area, the A/Ci curve for each shoot was modelled using the equations and Excel worksheet published by Sharkey et al. (2007). The equations used in the model are listed below for reference, though the complete model description and worksheet can be found online and downloaded at: http://www.blackwellpublishing.com/plantsci/pcecalculation/ .

The ITEX manual updated in 2011 also contains a description of how to process the LI-6400 data and use this model for A/Ci curve data.

The equations used in the A/Ci curve model are listed below, as described in Sharkey et al (2007):

Rubisco-limited photosynthesis:



Where:
A = rate of photosynthesis (umol CO2 m-2 s-1)
Vcmax = maximum velocity of Rubisco for carboxylation
Cc = partial pressure of CO2 at Rubisco
Kc = Michaelis constant of Rubisco for CO2
Omicron (?) = partial pressure of O2 at Rubisco
Ko = inhibition constant (usually taken to be the Michaelis constant) of Rubisco for O2
Rd = rate of respiration (umol CO2 m-2 s-1)
?* = CO2 concentration at which oxygenation proceeds at twice the rate of carboxylation, causing photosynthesis rate = respiration rate (photorespiration compensation point)

Rubisco regeneration-limited photosynthesis:




Where:
A = rate of photosynthesis (umol CO2 m-2 s-1)
J = rate of electron transport (assumes 4 electrons / carboxylation and oxygenation)
Cc = partial pressure of CO2 at Rubisco
Rd = rate of respiration (umol CO2 m-2 s-1)
?* = CO2 concentration at which oxygenation proceeds at twice the rate of carboxylation, causing photosynthesis rate = respiration rate (photorespiration compensation point)


Triose- phosphate unit (TPU)-limited photosynthes:


Where:

A = rate of photosynthesis (umol CO2 m-2 s-1)
TPU = rate of use of triose phosphates (can also be any export of C from the Calvin cycle)
Rd = rate of respiration (umol CO2 m-2 s-1)

Mesophyll Conductance (gm*)

Equations (1 ) - (3) were developed for chloroplast metabolism, and thus a relationship is needed between the chloroplast and leaf-level gas exchange. This is done through the mesophyll conductance constant calculated with equation (4):




Where:

Cc = partial pressure of CO2 at Rubisco (Pa)
Ci = intercellular CO2 concentration (umol CO2)
A = rate of photosynthesis (umol CO2 m-2 s-1)
gm = mesophyll conductance rate (umol CO2 m-2 s-1 Pa-1 )

POINT FRAME PIN-DROP METHODS:
We preferentially selected tall shrub canopies dominated either by Betula nana or Salix pulchra, that is canopies that were greater than 75 cm height. Care was taken to select fairly uniform canopies, that is avoiding the edge of a shrub stand or areas where the canopy had a large gaps, suggesting the area may have been disturbed.

We used point frames constructed from a 1.1 m x 1.1 m aluminum square with holes in each corner to accomodate steel rod posts used as the legs of the point frame. In this way, the frame could rest upon the four leg posts that had been hammered into the ground and remain adjustable in each corner. The frame had a level on each side, and great care was taken to ensure that the frame was (a) unable to be pushed deeper into the ground and, (b) level on all four sides prior to taking measurements. These factors were important to the measurement to have accurate data regarding the distance from the frame and the overall height of each point sampled in the canopy.

The aluminum frame had numbered, regularly spaced holes on two opposite sides in order to accomodate a metal bar that could be placed across the frame and locked into place. [These holes on the frame are the row numbers.] The bar that was placed across the frame similarly had numbered, evenly spaced holes in order to accomodate a pin--a long (100-200cm) metal rod with a diameter of ~3.175 mm. [The holes on this bar are the pin hole numbers.] Measurements were only ever taken from odd row numbers, and alternated even/odd pin hole numbers with each row; in this way, for every plot 25 evenly spaced locations were sampled covering an area of one square meter.

The length of the pin was marked every half-centimeter so that the distance could be read easily. Measurements were made by lowering the pin through a pin hole and, once encountering a leaf or stem, recording the following: row#, pin hole#, hit#, and the species hit. If the object hit was not a leaf, the plant tissue was noted; the diameter of each stem hit was estimated in millimeters, and the length of every graminoid blade hit was recorded from the point at which it was hit to the tip. As the primary species of interest for this project were for a select number of species (B. nana, S. pulchra, S. glauca, S. reticulata, V. uliginosum, V. vitis, L. palustre), species that were not the target of interest were classified as functional groups--e.g. graminoid spp., forb, moss.

The last pin-hit recorded for each pin hole was always at the "soil" which was considered to be the transition between the green and brown plant material, often in a mossy layer.

References:
Sharkey, T.D., Bernacchi, C. J., Farquar, G.D. and Singaas, E.L., 2007. Fitting photosynthetic carbon dioxide response curves for C3leaves. Plant, Cell and Environment, 30:10351040. doi:10.1111/j.1365-3040.2007.01710.x
http://www.blackwellpublishing.com/plantsci/pcecalculation/

ITEX Manual Updated in 2011.

Data Table

Variable Name Variable Description Data Type Units DateTime Format Code Information Missing Value Code
YEAR year of measurement datetime   YYYY    
DATE date of measurement datetime   DD-MMM-YY    
SITE Toolik text        
GROUP Measurement location in relation to Toolik Lake LTER Shrub plots; In vicinity of Block1 = Upland, IVO Block 2 = Outlet text        
PLOT Individual plot identifier text        
TREATMENT control or fertilized annually (with N and P) text        
PLOT SIZE 1m x 1m point frame size text        
DOMINANT VEGETATION Dominant canopy vegetation text        
SPP Shoot species sampled text        
SHOOT ID Identification for each shoot sampled (NOT unique); consists of canopy position (up/mid/low), species abbreviation, and a number text        
CANOPY POSN Relative position of shoot in the canopy text        
AMBIENT CO2 BEFORE MEASUREMENTS Carbon dioxide concentration in the room at the beginning of measurements (umol CO2 per mole air) number micromolePerMole     not recorded=Missing or Not Measured
AMBIENT CO2 AFTER MEASUREMENTS Carbon dioxide concentration in the room after taking measurements (umol CO2 per mole air) number micromolePerMole     not recorded=Missing or Not Measured
AVG LEAF TEMP Average leaf temperature during measurement (deg C) number celsius     #N/A=Missing or Not Measured
AVG PRESSURE Average pressure during measurement number atmosphere     #N/A=Missing or Not Measured
SUM(LEAF, PETIOLE, STIPULE) AREA Area of the shoot leaves, petioles, and stipules used to correct light curve data (square cm leaf+petiole+stipule) number centimeterSquared     #N/A=Missing or Not Measured
LMA Leaf mass per unit area (g leaf per square cm leaf) number gramPerMeterSquared     #N/A=Missing or Not Measured
Resp_Real Rate of CO2 change measured in the dark of light curve and used to estimate respiration rate (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Vcmax @LeafT Modeled CO2 assimilation at maximum carboxylation efficiency of the Rubisco enzyme at leaf temperature (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Jmax @LeafT Modeled CO2 assimilation at maximum electron transportation efficiency at leaf temperature (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
TPU @LeafT Modeled CO2 assimilation at maximum triose-phosphate utilization at leaf temperature (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Rd @LeafT Modeled respiration rate at leaf temperature (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
gm* @LeafT Modeled mesophyll conductance at leaf temperature (umol CO2 per meter squared leaf per second per Pascal) number micromolePerMeterSquaredPerSecondPerPascal     #N/A=Missing or Not Measured
Vcmax @25C Modeled CO2 assimilation at maximum carboxylation efficiency of the Rubisco enzyme at 25C (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Jmax @25C Modeled CO2 assimilation at maximum electron transportation efficiency at 25C (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
TPU @25C Modeled CO2 assimilation at maximum triose-phosphate utilization at 25C (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Rd @25C Modeled respiration rate at 25C (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
gm* @25C Modeled mesophyll conductance at 25C (umol CO2 per meter squared leaf per second per Pascal) number micromolePerMeterSquaredPerSecondPerPascal     #N/A=Missing or Not Measured
Ci 50 Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 50 umol CO2 (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 100 Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 100 umol CO2 (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 200 Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 200 umol CO2 number micromolePerMole     #N/A=Missing or Not Measured
Ci 300 Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 300 umol CO2 (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 400 (1) Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 400 umol CO2- first observation (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 400 (6) Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 400 umol CO2- sixth observation (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 400 (13) Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 400 umol CO2- thirteenth observation (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 500 Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 500 umol CO2 (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 700 Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 700 umol CO2 (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 900 Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 900 umol CO2 (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 1300 Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 1300 umol CO2 (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 1500 Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 1500 umol CO2 (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Ci 1700 Modeled CO2 concentration of the intercellular airspaces of the leaf when the target [CO2] was 1700 umol CO2 (umol CO2 per mole air) number micromolePerMole     #N/A=Missing or Not Measured
Photo @ CO2R 50 Photosynthetic rate when the target [CO2] was 50 umol CO2 (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 100 Photosynthetic rate when the target [CO2] was 100 umol CO2 (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 200 Photosynthetic rate when the target [CO2] was 200 umol CO2 (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 300 Photosynthetic rate when the target [CO2] was 300 umol CO2 (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 400 (1) Photosynthetic rate when the target [CO2] was 400 umol CO2 - first observation (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 400 (6) Photosynthetic rate when the target [CO2] was 400 umol CO2 - sixth observation (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 400 (13) Photosynthetic rate when the target [CO2] was 400 umol CO2 - thirteenth observation (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 500 Photosynthetic rate when the target [CO2] was 500 umol CO2 (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 700 Photosynthetic rate when the target [CO2] was 700 umol CO2 (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 900 Photosynthetic rate when the target [CO2] was 900 umol CO2 (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 1300 Photosynthetic rate when the target [CO2] was 1300 umol CO2 (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 1500 Photosynthetic rate when the target [CO2] was 1500 umol CO2 (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
Photo @ CO2R 1700 Photosynthetic rate when the target [CO2] was 1700 umol CO2 (umol CO2 per meter squared leaf per second) number micromolePerMeterSquaredPerSecond     #N/A=Missing or Not Measured
COMMENTS Notes on data quality and measurements text        

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