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Harvard Forest Data Archive

HF421

Impacts of Phloem Chilling on Mature Red Maples at Harvard Forest 2019

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Data

Overview

  • Lead: Tim Rademacher
  • Investigators: Andrew Richardson, Mark VanScoy
  • Contact: Information Manager
  • Start date: 2019
  • End date: 2019
  • Status: complete
  • Location: Prospect Hill Tract (Harvard Forest)
  • Latitude: +42.51 degrees
  • Longitude: -72.22 degrees
  • Elevation: 340 meter
  • Datum: WGS84
  • Taxa: Pinus strobus
  • Release date: 2023
  • Language: English
  • EML file: knb-lter-hfr.421.2
  • DOI: digital object identifier
  • EDI: data package
  • DataONE: data package
  • Related links:
  • Study type: short-term measurement
  • Research topic: forest-atmosphere exchange; large experiments and permanent plot studies; physiological ecology, population dynamics and species interactions
  • LTER core area: primary production
  • Keywords: aboveground biomass, carbohydrates, carbon, maple, respiration, tree growth, tree physiology, tree rings, wood
  • Abstract:

    Whether tree growth is limited by carbon supply or demand is a crucial question due to wide-ranging repercussions for projections of carbon sequestration on land. By temporarily restricting phloem transport using stem chilling, which increases phloem sap viscosity to create local bottlenecks to phloem transport, we created gradients of carbon supply in stems of mature red maples during the first half of the growing season. These carbon supply gradients had clear effects on tree physiology with radial growth in particular varying up to almost seven-fold with carbon supply. Local bulk nonstructural carbon concentrations in stems and roots remained relatively stable, suggesting that they are not rapidly modulated in response to changes in supply and demand. However, phloem and leaf nonstructural carbon accumulated above chilling-induced bottlenecks and were associated with reductions in photosynthetic capacity as well as the advancement of leaf coloration and fall, supporting the idea of within-tree feedbacks reducing carbon supply when supply exceeds demand. Most strikingly, radial growth varied systematically with carbon supply up to almost seven-fold, indicating that growth of red maple during the early growing season is strongly carbon-supply limited.

    The code to process these data and reproduce our results is available at https://github.com/TTRademacher/Exp2019Analysis. For more details pertaining to the methods see Rademacher et al. (2021) and contact the investigator.

  • Methods:

    All trees were monitored throughout the growing season from the beginning of April to early October. The chilling was switched on from the end of May to early July. During the chilling period we characterised radial growth, stem CO2 efflux, and root, nonstructural carbon content (soluble sugars and starch) for root, phloem, xylem and leaf tissues. Additionally, tree water status was measured throughout the growing season using sap flow sensors and leaf and branch water potential measurements. Finally, leaf phenology was observed in the shoulder seasons and photosynthesis and leaf fluorescence were measured towards the end of the chilling period in early July.

    Phloem chilling and temperature monitoring

    A cluster of eight mature red maples was divided into four groups of two similar trees in terms of size and canopy status. In the field, one tree of each pair was randomly assigned with a coin flip to a treatment group: control versus chilled. To monitor phloem tempertures we implanted negative temperature coefficient thermistors (2.5 mm diameter, SC30F103V, Amphenol Thermometrics Inc., St. Marys, Pennsylvania, USA) in the phloem at 1.0 and 2.0 m using surgical needles in early May 2019. Copper coil was thereafter wrapped around 30 cm of stem (centered on 1.0 and 2.0 m). The copper was linked to coolant supply loops with one ALPHA2 circulator (Grundfos, Bjerringbro, Denmark) per pair of trees. Chilling to the main supply line was provided by a six ton chiller (Chillking, Bastrop, Texas, USA), which was switched on and off to keep the chilling temperature in the main loop about 0°C. Main loop temperatures were monitored using 20 T_109 thermitors (Campbell Scientific, Edmonton, Alberta, Canada), which were calibrated in an ice-bath prior to deployment. Piping and chilling collars were insulated to reduce heat loss to the environments and covered in radiative barriers. The chilling was switched on and off on the 29 May 2019 and 20 Jul 2019, respectively.

    Wood formation and anatomy

    Tree-ring growth was characterised from stem microcores collected at four sampling heights on the stem with a Trephor (Rossi et al., 2006) starting in the beginning of April and ending in early October with one follow-up sample collected on the 4 Aug 2020. Ring widths were measured using the self-developed Wood Image Analysis and Database platform on microsection images captured using a digital slide-scanner (Zeiss Axio Scan.Z1, Germany) with a resolution of roughly 1.5 pixels per micrometer.

    Stem respiration

    Starting in April, an infrared gas analyser (LI-820, LI-COR, Lincoln, Nebraska, USA) with a circulating pump was attached to stem respiration chambers using a lid with two ports to constantly circulate air through the closed system (Carbone et al., 2019). The chamber CO2 concentration was measured at 1 Hz for at least one minute, once it had stabilised to ambient values. The raw stem CO2 efflux and uncertainties were estimated using the RespChamberProc package (http://r-forge.r-project.org/projects/respchamberproc/) as developed by Perez-Priego et al. (2015).

    Nonstructural carbon

    Soluble sugar and starch concentrations in coarse root, phloem, xylem, and leaf tissues were determined from samples collected regularly throughout the growing season. Coarse root (at least 20 cm below the root collar) and stem samples were collected using a 5.15 mm increment borer (Haglӧf Company Group, Långsele, Sweden). Stem cores were divided into phloem and the first centimetre of xylem adjacent to the phloem with a scalpel. About 40 mg of finely ground and dried powder for all tissue, tree and sampling date combinations was analysed following the protocol by Chow and Landhäusser (2004) using a colourimetric assay with phenol-sulphuric acid after ethanol extraction. Each batch of 40 samples included at least seven blanks and nine laboratory control standards of either red oak stem wood (Harvard Forest, Petersham, Massachusetts, USA) or potato starch (Sigma Chemicals, St. Louis, Missouri, USA). Absorbance for each batch were calibrated using a 1:1:1 glucose:fructose:galactose (Sigma Chemicals, St Louis, Missouri, USA) standard curve values using the self-developed R-package NSCprocessR (https://github.com/ttrademacher/NSCprocessR) to converted sample absorbances to concentrations in % dry weight and uncertainties.

    Water potential and sap flow

    Pre-dawn needle and branch water potential were measured biweekly with a pressure chamber (Model 600, PMS Instruments, Albany, Oregon, USA) throughout the growing season.

    For each measurement, the canopy of two adjacent trees (one chilled and one control tree) was reached with a canopy lift, two branch tips and two leaves per tree were severed with a razor blade. Within seconds of harvesting each sample, water potential was determined after re-cutting the tissue on a cutting board to have a clean edge and before moving onto the next sample. Observed needle and branch water potential did not differ among treatments during the duration of the experiment or in the remaining growing season. In addition to the leaf and branch water potential, we installed three needle heat-pulse sap flow sensors (East 30, Pullman, Washington, USA) in the early growing season on all trees (chilled and control trees) at a stem height of 1.5 m, which was between the two chilling collars for chilled trees. These sensors measure temperature at 5, 17.5 and 30 mm on the first and third needle and use the temperature differential before and after a heat pulse originating in the middle needle to estimate sap flow velocity at the three depths.

    Leaf phenology observations

    Leaf phenology was observed starting in the fall of 2018 and finishing in the fall of 2019 after the chilling had concluded. We followed the protocol by O’Keefe (2019). Using binoculars we visually observed the crown of each tree to determine the dates of bud burst, leaf elongation, leaf coloration and leaf fall.

    Photosynthesis and leaf fluorescence

    Towards the end of the chilling period, we also measured leaf photosynthesis and fluorescence from a canopy lift. Each set of measurements was performed simultaneously on one tree from the control group and one tree from the chilled group. Over a period of ten days we measured instantaneous photosynthetic rates, light response curves, and A/Ci curves using a LiCOR-6400 (Lincoln, Nebraska, USA). Directly after each measurement, we cut the leaf at the petiole and measured chlorophyll fluorescence using an OS-30P (Opti-Sciences, Hudson, New Hampshire, USA). Leaves were subsequently wrapped in aluminium foil and kept in a cooler with ice to dark-adapt. At the end of the day, we re-measured dark-adapted leaf fluorescence, weighed the leaves, scanned (3200 dpi, V600 Epson Perfection) and oven-dried them at 60°C for 24 hours, and weighed them again.

    For more details pertaining to the methods see Rademacher et al. (2021) or contact the lead investigator.

  • Organization: Harvard Forest. 324 North Main Street, Petersham, MA 01366, USA. Phone (978) 724-3302. Fax (978) 724-3595.

  • Project: The Harvard Forest Long-Term Ecological Research (LTER) program examines ecological dynamics in the New England region resulting from natural disturbances, environmental change, and human impacts. (ROR).

  • Funding: National Science Foundation LTER grants: DEB-8811764, DEB-9411975, DEB-0080592, DEB-0620443, DEB-1237491, DEB-1832210.

  • Use: This dataset is released to the public under Creative Commons CC0 1.0 (No Rights Reserved). Please keep the dataset creators informed of any plans to use the dataset. Consultation with the original investigators is strongly encouraged. Publications and data products that make use of the dataset should include proper acknowledgement.

  • License: Creative Commons Zero v1.0 Universal (CC0-1.0)

  • Citation: Rademacher T. 2023. Impacts of Phloem Chilling on Mature Red Maples at Harvard Forest 2019. Harvard Forest Data Archive: HF421 (v.2). Environmental Data Initiative: https://doi.org/10.6073/pasta/6a45cf16a9593a12370c251ae40369b1.

Detailed Metadata

hf421-01: nonstructural carbon concentrations

  1. sample.type: type of sample
  2. rc.lab.number: internal identification number for the Richardson and Carbone Lab
  3. sample.id: sample identifier
  4. tissue: tissue type
  5. batch.id: batch identifier
  6. sample.location: location where sample was collected
  7. date.of.sample.collection: date the sample was collected
  8. date.of.sugar.analysis: date the sugar extraction and anaylsis was done
  9. date.of.starch.analysis: date the starch extraction and analysis was done
  10. mass.of.empty.tube: mass of empty tube (unit: gram / missing value: NA)
  11. mass.of.tube.and.sample: mass of tube with the sample (unit: gram / missing value: NA)
  12. absorbance490.1: first absorbance value read at 490 nm (unit: dimensionless / missing value: NA)
  13. absorbance490.2: second absorbance value read at 490 nm (unit: dimensionless / missing value: NA)
  14. absorbance490.blank: absorbance value at 490 nm for the blank (unit: dimensionless / missing value: NA)
  15. absorbance525.1: first absorbance value read at 525 nm (unit: dimensionless / missing value: NA)
  16. absorbance525.2: second absorbance value read at 525 nm (unit: dimensionless / missing value: NA)
  17. dilution.factor.sugar: factor by which the sugar extract was diluted (unit: dimensionless / missing value: NA)
  18. volume.sugar: volume of the sugar extract (unit: milliliter / missing value: NA)
  19. dilution.factor.starch: factor by which the starch extract was diluted (unit: dimensionless / missing value: NA)
  20. volume.starch: volume of the starch extract (unit: milliliter / missing value: NA)
  21. comments: comments

hf421-02: stem respiration

  1. file: name of the raw data file
  2. study: name of the study group
  3. treatment: treatment group
    • 1: control
    • 4: double compressed
    • 5: chilled
  4. tree: tree identifier
  5. species: tree species
  6. chamber: chamber identifier
    • 1: 0.5 m above the ground
    • 2: 1.5 m above the ground
    • 3: 2.5 m above the ground
  7. chamber.volume: volume of the respiration chamber (unit: cubicMeter / missing value: NA)
  8. chamber.area: stem surface area covered by the chamber (unit: squareMeter / missing value: NA)
  9. datetime: time stamp of when the measurement started
  10. session: identifier for the session of respiration measurements
  11. flux.raw: mean respiratory flux from this chamber (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  12. sd.flux.raw: standard deviation of the respiratory flux from this chamber (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  13. aic.raw: Akaike Information Criterion of model fitted to respiration curve (unit: dimensionless / missing value: NA)
  14. r2.raw: R2 of fit to the respiration curve after correction for water vapour dilution using atmospheric humidity (unit: dimensionless / missing value: NA)
  15. flux.atm: mean respiratory flux after correction for water vapour dilution using internal humidity from this chamber (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  16. sd.flux.atm: standard deviation of the respiratory flux after correction for water vapour dilution using atmospheric humidity from this chamber (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  17. aic.atm: Akaike Information Criterion of model fitted to respiration curve after correction for water vapour dilution using atmospheric humidity (unit: dimensionless / missing value: NA)
  18. r2.atm: R2 of fit to the respiration curve after correction for water vapour dilution using atmospheric humidity (unit: dimensionless / missing value: NA)
  19. flux.int: mean respiratory flux after correction for water vapour dilution using internal humidity from this chamber (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  20. sd.flux.int: standard deviation of the respiratory flux after correction for water vapour dilution using internal humidity from this chamber (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  21. aic.int: Akaike Information Criterion of model fitted to respiration curve after correction for water vapour dilution using internal humidity (unit: dimensionless / missing value: NA)
  22. r2.int: R2 of fit to the respiration curve after correction for water vapour dilution using internal humidity (unit: dimensionless / missing value: NA)
  23. ea.pa: atmospheric pressure from the Fisher meteorological station (unit: pascal / missing value: NA)
  24. airt.c: surface air temperature from the Fisher meteorological station (unit: celsius / missing value: NA)
  25. soilt1.c: soil temperature at 2.25 cm near the Barn Tower (unit: celsius / missing value: NA)
  26. soilt2.c: soil temperature at 6.8 cm near the Barn Tower (unit: celsius / missing value: NA)
  27. soilt3.c: soil temperature at 12.85 cm near the Barn Tower (unit: celsius / missing value: NA)
  28. soilt4.c: soil temperature at 22.75 cm near the Barn Tower (unit: celsius / missing value: NA)
  29. pres.pa: atmospheric barometric pressure from the Fisher Meteorological station (unit: pascal / missing value: NA)
  30. h2o.ppt.atm: atmospheric humidity from the Fisher meteorological station in parts per thousand (unit: dimensionless / missing value: NA)
  31. h2o.ppt.int: internal atmospheric humidity from the Li-Cor 840 in parts per thousand (unit: dimensionless / missing value: NA)
  32. vwc.daily: daily mean volumetric water content from probes at the Barn Tower (unit: dimensionless / missing value: NA)
  33. vwc1: 10-minute mean volumetric water content at 2.25 cm near the Barn Tower (unit: dimensionless / missing value: NA)
  34. vwc2: 10-minute mean volumetric water content at 6.8 cm near the Barn Tower (unit: dimensionless / missing value: NA)
  35. vwc3: 10-minute mean volumetric water content at 12.85 cm near the Barn Tower (unit: dimensionless / missing value: NA)
  36. vwc4: 10-minute mean volumetric water content at 22.75 cm near the Barn Tower (unit: dimensionless / missing value: NA)
  37. total.rad: total downwelling shortwave radiation at top of Barn Tower (unit: wattPerMeterSquared / missing value: NA)
  38. diffuse.rad: diffuse downwelling shortwave radiation at top of Barn Tower (unit: wattPerMeterSquared / missing value: NA)

hf421-03: water potential

  1. date: date of measurement
  2. tree: tree identifier
  3. treatment: treatment
    • 1: control
    • 5: chilled
  4. phi.branch: mean pre-dawn branch water potential out of three measurements (unit: megapascal / missing value: "NA")
  5. phi.leaf: mean pre-dawn needle water potential out of three measurements (unit: megapascal / missing value: "NA")
  6. comments: comments

hf421-04: temperature data

  1. datetime: date and time of measurement
  2. record: number of record
  3. u.battery: battery voltage of data logger (unit: volt / missing value: NA)
  4. t.panel: temperature of data logger (unit: celsius / missing value: NA)
  5. t.oak.1p5m: control air temperature at 1.5 m on a neighbouring oak tree (unit: celsius / missing value: NA)
  6. t.acer.02.1p0m: phloem temperature underneath the lower chilling collar at 1.0 m on tree 02 (unit: celsius / missing value: NA)
  7. t.acer.02.2p0m: phloem temperature underneath the lower chilling collar at 2.0 m on tree (unit: celsius / missing value: NA)
  8. t.acer.04.1p0m: phloem temperature underneath the lower chilling collar at 1.0 m on tree 04 (unit: celsius / missing value: NA)
  9. t.acer.04.2p0m: phloem temperature underneath the lower chilling collar at 2.0 m on tree 04 (unit: celsius / missing value: NA)
  10. t.acer.06.1p0m: phloem temperature underneath the lower chilling collar at 1.0 m on tree 06 (unit: celsius / missing value: NA)
  11. t.acer.06.2p0m: phloem temperature underneath the lower chilling collar at 2.0 m on tree 06 (unit: celsius / missing value: NA)
  12. t.acer.07.1p0m: phloem temperature underneath the lower chilling collar at 1.0 m on tree 07 (unit: celsius / missing value: NA)
  13. t.acer.07.2p0m: phloem temperature underneath the lower chilling collar at 2.0 m on tree 07 (unit: celsius / missing value: NA)
  14. t.acer.01.1p0m: phloem temperature at 1.0 m on tree 01 (unit: celsius / missing value: NA)
  15. t.acer.01.2p0m: phloem temperature at 2.0 m on tree 01 (unit: celsius / missing value: NA)
  16. t.acer.03.1p0m: phloem temperature at 1.0 m on tree 03 (unit: celsius / missing value: NA)
  17. t.acer.03.2p0m: phloem temperature at 2.0 m on tree 03 (unit: celsius / missing value: NA)
  18. t.acer.05.1p0m: phloem temperature at 1.0 m on tree 05 (unit: celsius / missing value: NA)
  19. t.acer.05.2p0m: phloem temperature at 2.0 m on tree 05 (unit: celsius / missing value: NA)
  20. t.acer.08.1p0m: phloem temperature at 1.0 m on tree 08 (unit: celsius / missing value: NA)
  21. t.acer.08.2p0m: phloem temperature at 2.0 m on tree 08 (unit: celsius / missing value: NA)
  22. t.misc1: air temperature at 1.5 m underneath the canopy (unit: celsius / missing value: NA)
  23. t.misc2: air temperature at 2.0 m underneath the canopy (unit: celsius / missing value: NA)

hf421-05: boundaries

  1. image.name: file name of the image
  2. xDim: image dimension of the x-axis in pixels (unit: dimensionless / missing value: NA)
  3. yDim: dimension of the y-axis in pixels (unit: dimensionless / missing value: NA)
  4. img.rotation: necessary rotation before ROI extraction (unit: degree / missing value: NA)
  5. xMin2018: value at which the 2018 ROI starts on the x-axis in pixels (unit: dimensionless / missing value: NA)
  6. xMax2018: value at which the 2018 ROI ends on the x-axis in pixels (unit: dimensionless / missing value: NA)
  7. yMin2018: value at which the 2018 ROI starts on the x-axis in pixels (unit: dimensionless / missing value: NA)
  8. yMax2018: value at which the 2018 ROI ends on the x-axis in pixels (unit: dimensionless / missing value: NA)
  9. xMin2019: value at which the 2019 ROI starts on the x-axis in pixels (unit: dimensionless / missing value: NA)
  10. xMax2019: value at which the 2019 ROI ends on the x-axis in pixels (unit: dimensionless / missing value: NA)
  11. yMin2019: value at which the 2019 ROI starts on the x-axis in pixels (unit: dimensionless / missing value: NA)
  12. yMax2019: value at which the 2019 ROI ends on the x-axis in pixels (unit: dimensionless / missing value: NA)

hf421-06: instantaneous photosynthetic rates

  1. study: study
  2. tree: tree identifier
  3. treatment: treatment group
  4. leaf: leaf identifier
  5. position: position in the canopy, which is either “top” for sun-exposed leaves or “bottom” for shade leaves
  6. date: date of measurement
  7. time: time of measurement
  8. photosynthetic.rate.1: first measurement of instantaneous photosynthetic rate (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  9. photosynthetic.rate.2: second measurement of instantaneous photosynthetic rate (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  10. photosynthetic.rate.3: third measurement of instantaneous photosynthetic rate (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  11. photosynthetic.rate.4: fourth measurement of instantaneous photosynthetic rate (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  12. photosynthetic.rate.5: fifth measurement of instantaneous photosynthetic rate (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  13. fresh.weight: fresh weight of the leaf (unit: milligram / missing value: NA)
  14. dry.weight: dry weight of the leaf (unit: milligram / missing value: NA)
  15. moisture.content: percent moisture content of the leaf (unit: dimensionless / missing value: NA)
  16. comments: comments

hf421-07: A/Ci curves

  1. date: date of measurement
  2. record: number of record
  3. time: time of measurement
  4. position: position in the canopy, which is either “top” for sun-exposed leaves or “bottom” for shade leaves
  5. study: study
  6. tree: tree identifier
  7. leaf: leaf identifier
  8. FTime: flow time (unit: second / missing value: NA)
  9. photosynthetic.rate: measurement of photosynthetic rate (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  10. conductance: conductance to H2O (unit: molePerMeterSquaredPerSecond / missing value: NA)
  11. ci: intercellular CO2 concentration (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  12. tr.mmol: transpiration rate (unit: millimolePerMeterSquaredPerSecond / missing value: NA)
  13. vpd: vapour pressure deficit based on leaf temperature (unit: kilopascal / missing value: NA)
  14. ct.leaf: temperature of leaf thermocouple (unit: celsius / missing value: NA)
  15. area: in-chamber leaf area on which the measurement was performed (unit: centimeterSquared / missing value: NA)
  16. BLC_1: one-side boundary layer conductance (unit: molePerMeterSquaredPerSecond / missing value: NA)
  17. StmRat: stomatal ratio estimate (unit: dimensionless / missing value: NA)
  18. BLCond: total boundary layer conductance (unit: molePerMeterSquaredPerSecond / missing value: NA)
  19. t.air: air temperature (unit: celsius / missing value: NA)
  20. t.leaf: leaf temperature (unit: celsius / missing value: NA)
  21. t.bulk: bulk temperature (unit: celsius / missing value: NA)
  22. co2.r: CO2 concentration in the reference cell (unit: micromolePerMole / missing value: NA)
  23. co2.s: CO2 concentration in the sample cell (unit: micromolePerMole / missing value: NA)
  24. h2o.r: H2O concentration in the reference cell (unit: micromolePerMole / missing value: NA)
  25. h2o.s: H2O concentration in the sample cell (unit: micromolePerMole / missing value: NA)
  26. rh.r: relative humidity in the reference cell (unit: dimensionless / missing value: NA)
  27. rh.s: relative humidity in the sample cell (unit: dimensionless / missing value: NA)
  28. flow: flow rate (unit: millimolePerSecond / missing value: NA)
  29. par.i: photosynthetically active radiation inside the chamber (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  30. par.o: photosynthetically active radiation outside the chamber (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  31. press: atmospheric pressure photosynthetically active radiation inside the chamber (unit: kilopascal / missing value: NA)
  32. CsMch: sample CO2 offset (unit: micromolePerMole / missing value: NA)
  33. HsMch: sample H2O offset (unit: millimolePerSecond / missing value: NA)
  34. StableF: flag whether the feed flow is stable (unit: dimensionless / missing value: NA)
  35. BLCslope: slope of the boundary layer conductance of the leaf (unit: dimensionless / missing value: NA)
  36. BLCoffst: offset of the boundary layer conductance of the leaf (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  37. t.air.k: air temperature (unit: kelvin / missing value: NA)
  38. t.wall.k: wall temperature (unit: kelvin / missing value: NA)
  39. rad: flag whether radians are used for trigonometrics functions (unit: dimensionless / missing value: NA)
  40. Tl-Ta: difference in leaf and air temperature (unit: celsius / missing value: NA)
  41. CndTotal: total conductance (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  42. vp_kPa: vapour pressure (unit: kilopascal / missing value: NA)
  43. vpd.a: vapour pressure deficit based on air temperature (unit: kilopascal / missing value: NA)
  44. CndCO2: CO2 conductance (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  45. ci.Pa: intercellular CO2 concentration (unit: micromolePerMole / missing value: NA)
  46. Ci.Ca: ratio of intercellular over ambient CO2 concentration (unit: micromolePerMole / missing value: NA)

hf421-08: light response curves

  1. date: date of measurement
  2. record: number of record
  3. time: time of measurement
  4. position: position in the canopy, which is either “top” for sun-exposed leaves or “bottom” for shade leaves
  5. study: study
  6. tree: tree identifier
  7. leaf: leaf identifier
  8. FTime: flow time (unit: second / missing value: NA)
  9. photosynthetic.rate: measurement of photosynthetic rate (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  10. conductance: conductance to H2O (unit: molePerMeterSquaredPerSecond / missing value: NA)
  11. ci: intercellular CO2 concentration (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  12. tr.mmol: transpiration rate (unit: millimolePerMeterSquaredPerSecond / missing value: NA)
  13. vpd: vapour pressure deficit based on leaf temperature (unit: kilopascal / missing value: NA)
  14. ct.leaf: temperature of leaf thermocouple (unit: celsius / missing value: NA)
  15. area: in-chamber leaf area on which the measurement was performed (unit: centimeterSquared / missing value: NA)
  16. BLC_1: one-side boundary layer conductance (unit: molePerMeterSquaredPerSecond / missing value: NA)
  17. StmRat: stomatal ratio estimate (unit: dimensionless / missing value: NA)
  18. BLCond: total boundary layer conductance (unit: molePerMeterSquaredPerSecond / missing value: NA)
  19. t.air: air temperature (unit: celsius / missing value: NA)
  20. t.leaf: leaf temperature (unit: celsius / missing value: NA)
  21. t.bulk: bulk temperature (unit: celsius / missing value: NA)
  22. co2.r: CO2 concentration in the reference cell (unit: micromolePerMole / missing value: NA)
  23. co2.s: CO2 concentration in the sample cell (unit: micromolePerMole / missing value: NA)
  24. h2o.r: H2O concentration in the reference cell (unit: micromolePerMole / missing value: NA)
  25. h2o.s: H2O concentration in the sample cell (unit: micromolePerMole / missing value: NA)
  26. rh.r: relative humidity in the reference cell (unit: dimensionless / missing value: NA)
  27. rh.s: relative humidity in the sample cell (unit: dimensionless / missing value: NA)
  28. flow: flow rate (unit: millimolePerSecond / missing value: NA)
  29. par.i: photosynthetically active radiation inside the chamber (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  30. par.o: photosynthetically active radiation outside the chamber (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  31. press: atmospheric pressure photosynthetically active radiation inside the chamber (unit: kilopascal / missing value: NA)
  32. CsMch: sample CO2 offset (unit: micromolePerMole / missing value: NA)
  33. HsMch: sample H2O offset (unit: millimolePerSecond / missing value: NA)
  34. StableF: flag whether the feed flow is stable (unit: dimensionless / missing value: NA)
  35. BLCslope: slope of the boundary layer conductance of the leaf (unit: dimensionless / missing value: NA)
  36. BLCoffst: offset of the boundary layer conductance of the leaf (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  37. t.air.k: air temperature (unit: kelvin / missing value: NA)
  38. t.wall.k: wall temperature (unit: kelvin / missing value: NA)
  39. rad: flag whether radians are used for trigonometrics functions (unit: dimensionless / missing value: NA)
  40. Tl-Ta: difference in leaf and air temperature (unit: celsius / missing value: NA)
  41. CndTotal: total conductance (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  42. vp_kPa: vapour pressure (unit: kilopascal / missing value: NA)
  43. vpd.a: vapour pressure deficit based on air temperature (unit: kilopascal / missing value: NA)
  44. CndCO2: CO2 conductance (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  45. ci.Pa: intercellular CO2 concentration (unit: micromolePerMole / missing value: NA)
  46. Ci.Ca: ratio of intercellular over ambient CO2 concentration (unit: micromolePerMole / missing value: NA)

hf421-09: leaf fluorescence

  1. study: study
  2. tree: tree identifier
  3. treatment: treatment group
  4. leaf: leaf identifier
  5. position: position in the canopy, which is either “top” for sun-exposed leaves or “bottom” for shade leaves
  6. date: date of measurement
  7. time: time of measurement
  8. Fo.1: first measurement of minimum fluorescence (unit: dimensionless / missing value: NA)
  9. Fm.1: first measurement of maximum fluorescence (unit: dimensionless / missing value: NA)
  10. FvOverFm.1: first measurement of the ratio of variable and maximum fluorescence (unit: dimensionless / missing value: NA)
  11. Fo.2: second measurement of minimum fluorescence (unit: dimensionless / missing value: NA)
  12. Fm.2: second measurement of maximum fluorescence (unit: dimensionless / missing value: NA)
  13. FvOverFm.2: second measurement of the ratio of variable and maximum fluorescence (unit: dimensionless / missing value: NA)
  14. Fo.3: third measurement of minimum fluorescence (unit: dimensionless / missing value: NA)
  15. Fm.3: third measurement of maximum fluorescence (unit: dimensionless / missing value: NA)
  16. FvOverFm.3: third measurement of the ratio of variable and maximum fluorescence (unit: dimensionless / missing value: NA)
  17. Fo.4: fourth measurement of minimum fluorescence (unit: dimensionless / missing value: NA)
  18. Fm.4: fourth measurement of maximum fluorescence (unit: dimensionless / missing value: NA)
  19. FvOverFm.4: fourth measurement of the ratio of variable and maximum fluorescence (unit: dimensionless / missing value: NA)
  20. Fo.5: fifth measurement of minimum fluorescence (unit: dimensionless / missing value: NA)
  21. Fm.5: fifth measurement of maximum fluorescence (unit: dimensionless / missing value: NA)
  22. FvOverFm.5: fifth measurement of the ratio of variable and maximum fluorescence (unit: dimensionless / missing value: NA)
  23. Fo.dark.1: first measurement of dark-adapted minimum fluorescence (unit: dimensionless / missing value: NA)
  24. Fm.dark.1: first measurement of dark-adapted maximum fluorescence (unit: dimensionless / missing value: NA)
  25. FvOverFm.dark.1: first measurement of the dark-adapted ratio of variable and maximum fluorescence (unit: dimensionless / missing value: NA)
  26. Fo.dark.2: second measurement of dark-adapted minimum fluorescence (unit: dimensionless / missing value: NA)
  27. Fm.dark.2: second measurement of dark-adapted maximum fluorescence (unit: dimensionless / missing value: NA)
  28. FvOverFm.dark.2: second measurement of the dark-adapted ratio of variable and maximum fluorescence (unit: dimensionless / missing value: NA)
  29. Fo.dark.3: third measurement of dark-adapted minimum fluorescence (unit: dimensionless / missing value: NA)
  30. Fm.dark.3: third measurement of dark-adapted maximum fluorescence (unit: dimensionless / missing value: NA)
  31. FvOverFm.dark.3: third measurement of the dark-adapted ratio of variable and maximum fluorescence (unit: dimensionless / missing value: NA)
  32. Fo.dark.4: fourth measurement of dark-adapted minimum fluorescence (unit: dimensionless / missing value: NA)
  33. Fm.dark.4: fourth measurement of dark-adapted maximum fluorescence (unit: dimensionless / missing value: NA)
  34. FvOverFm.dark.4: fourth measurement of the dark-adapted ratio of variable and maximum fluorescence (unit: dimensionless / missing value: NA)
  35. Fo.dark.5: fifth measurement of dark-adapted minimum fluorescence (unit: dimensionless / missing value: NA)
  36. Fm.dark.5: fifth measurement of dark-adapted maximum fluorescence (unit: dimensionless / missing value: NA)
  37. FvOverFm.dark.5: fifth measurement of the dark-adapted ratio of variable and maximum fluorescence (unit: dimensionless / missing value: NA)
  38. fresh.weight: weight of the leaf when collected (unit: gram / missing value: NA)
  39. dry.weight: weight of the leaf after oven-drying (unit: gram / missing value: NA)
  40. moisture.content: moisture content of the leaf (unit: dimensionless / missing value: NA)
  41. comments: comments