BOREAS TE-04 Gas Exchange Data from Boreal Tree Species

Summary

Measurements of light, CO~2~, temperature, and humidity response curves
were made by the BOREAS TE-04 team during the summary of 1994 using
intact attached leaves of boreal forest species located in the BOREAS
SSA. These measurements were conducted to calibrate models used to
predict photosynthesis, stomatal conductance, and leaf respiration. The
data can be used to construct plots of response functions or for
parameterizing models. Parameter values suitable for application in SiB2
(Sellers et al., 1996) or the leaf model of Collatz et al. (1991) and
programs can be obtained from the investigators. The data are stored in
tabular ASCII files.

Table of Contents

1 Data Set Overview

2 Investigator(s)

3 Theory of Measurements

4 Equipment

5 Data Acquisition Methods

5 Observations

7 Data Description

8 Data Organization

9 Data Manipulations

10 Errors

11 Notes

12 Application of the Data Set

13 Future Modification and Plans

14 Software

15 Data Access

16 Output Products and Availability

17 References

18 Glossary of Terms

19 List of Acronyms

20 Document Information

1\. Data Set Overview

1.1 Data Set Identification

BOREAS TE-04 Gas Exchange Data from Boreal Tree Species

1.2 Data Set Introduction

These data are summaries of steady-state gas exchange measurements
conducted by the Terrestrial Ecology (TE)-04 team under field conditions
in the summer of 1994 at the BOReal Ecosystem-Atmosphere Study (BOREAS)
Southern Study Area (SSA).

1.3 Objective/Purpose

These studies were conducted to provide a basis for calibrating models
of stomatal conductance, photosynthesis, and respiration used in
simulating boreal ecosystem-atmosphere interactions.

1.4 Summary of Parameters

The parameters provided in each data set are intended to provide a
sufficient description of the micro-environment of the leaf to permit
the observations to be used for model validation. A complete list of the
parameters is given in section 4.1.4. The key measurements are the rates
of net CO~2~ exchange, the rate of evaporation of water from the leaf,
the stomatal conductance to water vapor, and the intercellular CO~2~
concentration.

1.5 Discussion

These data have been analyzed by nonlinear curve fitting programs to
obtain parameter values suitable for application in SiB2 (Sellers et
al., 1996) or the leaf model of Collatz et al. (1991). Validation of
these calibration experiments is still in progress. Measurements of gas
exchange under ambient conditions (nonsteady-state) with LiCOR 6200
instruments and studies with branch bags by the TE-11 team have been
used for validation. Validation experiments indicate that photosynthesis
is accurately predicted by models based on these data. However, stomatal
conductance of conifer species is underpredicted. The source of this
problem has not been identified. Tree species measured were black spruce
(Picea mariana), aspen (Populus tremuloides), jack pine (Pinus
banksiana), white spruce (Picea glauca), birch (Betula pumila), and
hazel (Corylus cornuta).

1.6 Related Data Sets

BOREAS TE-05 CO~2~ Concentration and Stable Isotope Composition

BOREAS TE-09 NSA Photosynthetic Capacity and Foliage Nitrogen Data

BOREAS TE-09 PAR and Leaf Nitrogen Data for NSA Species

BOREAS TE-09 NSA Photosynthetic Response Data

BOREAS TE-09 NSA in situ Diurnal Gas Exchange of Boreal Forest Species

BOREAS TE-10 Leaf Optical Properties

BOREAS TE-12 Leaf Optical Data for SSA Species

BOREAS TE-12 Leaf Gas Exchange Data

2\. Investigator(s)

2.1 Investigator(s) Name and Title

Dr. Joseph A. Berry

Dr. G. James Collatz

Dr. John Gamon

Dr. Wei Fu

Dr. Art Fredeen

2.2 Title of Investigation

Measurement and Prediction of CO~2~ and H~2~O Exchange from Boreal
Forest Tree Species

2.3 Contact Information

[Contact 1:]{.underline}

Dr. Joseph A. Berry

Department of Plant Biology

Carnegie Institution of Washington

Stanford, CA

\(650\) 325-1521 ext. 221

\(650\) 325-6857 (fax)

joeberry@biosphere.stanford.edu

[Contact 2:]{.underline}

Dr. G. James Collatz

NASA GSFC

Greenbelt, MD

\(301\) 386-1425

\(301\) 286-0239 (fax)

jcollatz@biome.gsfc.nasa.gov

[Contact 3:]{.underline}

Dr. John Gamon

Department of Biology

California State University

Los Angeles, CA

\(213\) 343-2066

\(213\) 343-2670 (fax)

jgamon@bio10sun.calstatela.edu

[Contact 4:]{.underline}

Dr. Wei Fu

Carnegie Institution of Washington

Stanford, CA

[Contact 5:]{.underline}

Dr. Art Fredeen,

Fac. of Natural Resources and Environmental Studies

University of N.B.C.

Prince George, British Columbia

Canada

[Contact 6:]{.underline}

Shelaine Curd

Raytheon STX Corporation

NASA GSFC

Greenbelt, MD

\(301\) 286-2447

\(301\) 286-0239 (fax)

shelaine.curd@gsfc.nasa.gov

3\. Theory of Measurements

The measurements reported here were made by generally accepted
procedures for laboratory gas exchange. Leaves were enclosed in a
cuvette that permitted precise control of the leaf environment
(illumination, concentrations of CO2 and H~2~O, and temperature).

Net exchange of CO~2~ and H~2~O was determined by infrared gas analysis
of the air flowing through the stirred cuvette. See Field et al. (1989)
for more information.

4\. Equipment

4.1 Sensor/Instrument Description

Gas exchange system (Model MPH-1000; Campbell Scientific, Logan, UT)

Infrared Gas Analyzer (IRGA) (Model 6262; LiCor Inc., Lincoln NE)

Dew Point Mirror (Model Dew-10; General Eastern, Woburn, MA)

4.1.1 Collection Environment

All experiments were conducted with intact attached leaves/needles near
the top of canopies in the BOREAS SSA. For specific weather conditions
on experiment days, see meteorological data files.

4.1.2 Source/Platform

Equipment was located on canopy access towers.

4.1.3 Source/Platform Mission Objectives

The experiments were conducted to calibrate models of photosynthesis,
stomatal regulation, and respiration for canopy leaves/needles.

4.1.4 Key Variables

atmospheric pressure

boundary layer resistance

ambient water vapor pressure

ambient CO~2~ concentration

ambient temperature

flux density of photosynthetically active radiation (PAR)

short-wave radiation

long-wave radiation

leaf temperature

CO~2~ concentration at leaf surface

relative humidity at leaf surface

CO~2~ concentration in intercellular air spaces

net photosynthetic rate

stomatal conductance

transpiration rate

4.1.5 Principles of Operation

Temperature, CO~2~ concentration and H~2~O vapor pressure were
determined with appropriate sensors. Net CO~2~ and H~2~O exchange was
determined by mass balance analysis of the air flowing through the
cuvette. Gas exchange parameters, Ci, Gsw were calculated.

4.1.6 Sensor Instrument Measurement Geometry

Leaves/needles were enclosed in a cuvette. All measurements are
expressed on a leaf area basis; for the conifers, this is reported as
the hemisurface area of the needles (half of the total surface area) as
determined by volume displacement (J. Norman, personal communication);
the area of bilateral leaves is expressed as the single-sided area or
projected area.

4.1.7 Manufacturer of Sensor/Instrument

Gas exchange system (Model MPH-1000; Campbell Scientific, Logan UT)

IRGA (Model 6262; LiCor, Inc., Lincoln, NE)

Dew Point Mirror (Model Dew-10; General Eastern, Woburn, MA)

4.2 Calibration

CO~2~ concentration was referenced to standard CO~2~ tanks provided by
BOREAS.

H~2~O vapor was referenced to a dew point mirror instrument.

Air flow was calibrated by volume displacement.

PAR flux was referenced to a LiCor quantum probe.

4.2.1 Specifications

There are no published specifications for the complete system of
instruments used in this study.

4.2.1.1 Tolerance

All calibrations are better than +/- 1%.

4.2.2 Frequency of Calibration

Calibration and instrument zeros were checked daily. Checks against the
BOREAS gas standards occurred every week or two.

4.2.3 Other Calibration Information

No significant adjustments or drift of calibration occurred over the
interval of these measurements.

5\. Data Acquisition Methods

These measurements were decoupled from the ambient environment. There is
no direct correspondence between the temperature, light intensity, or
other environmental conditions in the cuvette during these experiments
and the ambient environmental conditions at the site of the
measurements.

In each gas exchange experiment, chamber CO~2~ concentration (Ca),
incident flux density of PAR (PFD), or chamber air temperature (Ta) was
varied while other factors were held constant. Generally, it took about
30 minutes for stomatal conductance and photosynthetic rate to reach
steady-state after the conditions were changed. The transient responses
were monitored, but data were reported only when the leaves had reached
steady-state at a new condition. CO~2~ responses were measured at a high
PFD (about 1000 μmol m^-2^ s^-1^) and a high chamber humidity (70%-80%)
at various temperatures. For light response curves, the leaf was
preconditioned to 1000 μmol m^-2^ s^-1^; light was then increased in
increments of about 300 μmol m^-2^ s^-1^ until saturation was evident
and then decreased in steps to zero. Temperature responses were measured
by increasing the chamber temperature while PFD was rate-saturating and
keeping the dew point temperature of inlet air constant. The starting
temperature was low (about 15 °C) and the chamber temperature was
increased by about 2.5 °C per step up to the highest chamber temperature
that the gas exchange system could reach in field (about 38 °C). This
protocol was chosen to mimic the covariation of leaf temperature and
vapor pressure deficit that occurs naturally on warm, dry days in this
environment. Dark respiration was measured in CO~2~-free air. These
conditions were chosen to obtain maximum sensitivity and stability to
resolve the small differentials of CO~2~ concentration produced by
respiration. The pattern of increasing chamber temperature was the same
as that in the measurements of temperature response of net
photosynthetic rate.

6\. Observations

6.1 Data Notes

These experiments were conducted over a 2-month interval, spending a few
consecutive days at each site. The studies were conducted with a few
selected leaves at each site. TE-04 team members believe that these
measurements are representative of the leaves at the site, but it was
not possible to obtain a statistically representative sample.
Measurements conducted with clip-on instruments such as the LiCor 6200
photosynthesis system can be used to assess variation in leaf properties
with time and location at these sites.

6.2 Field Notes

Not available.

7\. Data Description

7.1 Spatial Characteristics

7.1.1 Spatial Coverage

These are single leaf measurements taken in the SSA at the Old Aspen
(BOREAS site id = C3B7T), Old Jack Pine (G2L3T), Young Jack Pine
(F8L6T), Old Black Spruce (G8I4T), and the Mixed stand.

7.1.2 Spatial Coverage Map

Not available.

7.1.3 Spatial Resolution

The leaf area used in these measurements was typically 15-20 cm^2^ on a
given tree branch at the site.

7.1.4 Projection

Not applicable.

7.1.5 Grid Description

Not applicable.

7.2 Temporal Characteristics

7.2.1 Temporal Coverage

Data were collected over a 2-month interval starting in 21-Jul and
ending in 01-Sep-1994.

7.2.2 Temporal Coverage Map

Not available.

7.2.3 Temporal Resolution

In most cases, data were taken during a series of days at the same site.

7.3 Data

Data characteristics are defined in the companion data definition file
(te04gxda.def).

7.4 Sample Data

Sample data format shown in the companion data definition file
(te04gxda.def).

8\. Data Organization

8.1 Data Granularity

All of the Gas Exchange Data from Boreal Tree Species are contained in
one dataset.

8.2 Data Format

The data files contain numerical and character fields of varying length
separated by commas. The character fields are enclosed with a single
apostrophe marks. There are no spaces between the fields. Sample data
records are shown in the companion data definition file (te04gxda.def).

9\. Data Manipulations

9.1 Formulae

Calculation of gas exchange parameters was conducted essentially as
described by Ball (1987).

9.1.1 Derivation Techniques and Algorithms

Calculation of gas exchange parameters was conducted essentially as
described by Ball (1987).

9.2 Data Processing Sequence

Data were logged by a laptop computer and calculations were conducted
concurrent with the measurements. All of the primary data are archived.

9.2.1 Processing Steps

The data points presented represent the mean of at least five sequential
measurements.

9.2.2 Processing Changes

None given.

9.3 Calculations

The calculations are as described by Ball (1987).

9.3.1 Special Corrections/Adjustments

None given.

9.3.2 Calculated Variables

Calculation of gas exchange parameters was conducted essentially as
described by Ball (1987).

9.4 Graphs and Plots

Plots of these experiments are available as PostScript files by
anonymous ftp to biosphere.stanford.edu. Some of these may be found in
the directory,/submissions/Boreas_data/PS_files

10\. Errors

10.1 Sources of Error

Uncertainty in these experiments arises from instrument noise and
systematic calibration errors, and because the leaf experiences somewhat
different conditions in the cuvette (e.g. spectral composition or
anisotropy of light) than it would in a natural environment.

10.2 Quality Assessment

10.2.1 Data Validation by Source

The calibration data sets derived from analysis of these data are being
checked against observations of CO~2~ and water vapor exchange taken at
various scales: (a) independent leaf-scale measurements (b) branch-scale
measurements made by TE-11, and (c) flux observations made at the
respective towers.

10.2.2 Confidence Level/Accuracy Judgment

These data have been carefully checked and are equal in quality to
measurements conducted under laboratory conditions.

10.2.3 Measurement Error for Parameters

Gsw, stomatal conductance, +/- 5 μmol/(m^2^sec)

A, net CO~2~ exchange, +/- 0.1 mmol m^-2^ s^-1^

Ci, intercellular CO~2~, +/- 5 mmol/mol

10.2.4 Additional Quality Assessments

None.

10.2.5 Data Verification by Data Center

Data were examined for general consistency and clarity.

11\. Notes

11.1 Limitations of the Data

Unknown

11.2 Known Problems with the Data

The stomatal conductance observed with conifer species in these
experiments is uniformly lower than that which occurs under similar
environmental conditions in nature, possibly because the
tungsten-halogen lamp used for illumination in these experiments
contains less blue light than natural sunlight. The studies with aspen,
hazel, and birch appear to be okay. Another problem with the conifer
data sets concerns relating these measurements to the estimates of leaf
area made at the canopy-scale. The measurements reported here are for
actual hemispheric leaf area. The canopy-scale estimates reported by the
BOREAS Remote Sensing Science (RSS)-23 team and others are an
\"effective leaf area\" obtained by inversion of a radiation transport
model. The exact correspondence between these different measures of leaf
area is not known.

11.3 Usage Guidance

Validation experiments indicate that the stomatal slope parameter,
gradn, used in SiB2 or the Collatz et al. (1990) model should be
approximately 7 for black spruce and jack pine. The effective vmax0 of
needles should be increased for canopy simulations to account for
clumping and self shading of needles.

11.. Other Relevant Information

None.

12\. Application of the Data Set

The data set has been analyzed by nonlinear curve fitting programs to
obtain parameters for models. These parameters will eventually be made
available for distribution. Preliminary estimates can be obtained from
J. Berry.

13\. Future Modification and Plans

Additional measurements are planned for the summer of 1996 to address
the problems with stomatal conductance and questions.

14\. Software

Copies of SiB2 or the Collatz et al. (1991) model can be obtained from
J. Berry.

14.1 Software Description

SiB2 is in FORTRAN and runs in a workstation environment.

The Collatz et al. (1991) model is in C and can be run on PCs or
workstations.

14.2 Software Access

Copies of SiB2 or the Collatz et al. (1991) model can be obtained from
J. Berry.

15\. Data Access

15.1 Contact Information

Ms. Beth Nelson

BOREAS Data Manager

NASA GSFC

Greenbelt, MD

\(301\) 286-4005

\(301\) 286-0239 (fax)

Elizabeth.Nelson@gsfc.nasa.gov

15.2 Data Center Identification

See Section 15.1.

15.3 Procedures for Obtaining Data

Users may place requests by telephone, electronic mail, or fax.

15.4 Data Center Status/Plans

The TE-04 gas exchange data are available from the Earth Observing
System Data and Information System (EOSDIS), Oak Ridge National
Laboratory (ORNL), Distributed Active Archive Center (DAAC). The BOREAS
contact is ORNL is:

ORNL DAAC User Services

Oak Ridge National Laboratory

\(865\) 241-3952

ornldaac@ornl.gov

<ornl@eos.nasa.gov>

16\. Output Products and Availability

16.1 Tape Products

None.

16.2 Film Products

None.

16.3 Other Products

American Standard Code for Information Interchange (ASCII) files.

17\. References

17.1 Platform/Sensor Instrument/Data Processing Documentation

None.

17.2 Journal Articles and Study Reports

Ball, J.T. 1987. Calculations related to gas exchange. In:

E. Zeiger, G.D. Farquhar and I.R. Cowan (Eds.), Stomatal Function,

Stanford University Press, Stanford. pp 446-476.

Collatz, G.J., J. T. Ball, C. Grivet, and J.A. Berry. 1991.
Physiological and environmental regulation of stomatal conductance,
photosynthesis and transpiration: a model that includes a laminar
boundary layer. Agricultural and Forest Meteorology, 54, 107-36.

Field, C.B., J. T. Ball, and J.A. Berry. 1989. Photosynthesis:
principles and

field techniques. In: Plant Physiological Ecology: Field Methods and

Instrumentation, Edited by, R.W. Pearcy, J.R. Ehleringer, H.A. Mooney,
P.W.

Rundel. Chapman and Hall, London and New York, pp. 209 - 254.

Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study:
Experiment

Plan. Version 1994-3.0 NASA BOREAS Report (EXPLAN 94).

Sellers, P. and F. Hall. 1996. Boreal Ecosystem-Atmosphere Study:
Experiment

Plan. Version 1996-2.0 NASA BOREAS Report (EXPLAN 96).

Sellers, P. and F. Hall. 1997. BOREAS Overview Paper. JGR BOREAS Special
Issue, 201.

Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal
Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC
94).

Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal
Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC
96).

Sellers, P., F. Hall, H. Margolis, B. Kelly, D. Baldocchi, G. den
Hartog, J. Cihlar, M.G. Ryan, B. Goodison, P. Cril,l K.J. Ranson, D.
Lettenmaier, and D.E. Wickland. 1995. The boreal ecosystem-atmosphere
study (BOREAS): an overview and early results from the 1994 field year.
Bulletin of the American Meteorological Society. 76(9):1549-1577.

Sellers, P.J, D.R. Randall, G.J. Collatz, J.A. Berry, C.B. Field, D.A.
Dazlich, and G.D. Collelo. 1996. A revised land-surface parameterization
(SiB2) for GCMs. Part 1: Model formulation, Journal of Climate, 9,
676-705.

17.3 Archive/DBMS Usage Documentation

None.

18\. Glossary of Terms

None.

19\. List of Acronyms

ASCII - American Standard Code for Information Interchange

BOREAS - BOReal Ecosystem-Atmosphere Study

BORIS - BOREAS Information System

Ca - Ambient CO~2~ concentration

Ci - CO~2~ concentration in intercellular air spaces

Cs - CO~2~ concentration at leaf surface

DAAC - Distributed Active Archive Center

E - Transpiration rate

ea - ambient water vapor pressure

EOS - Earth Observing System

EOSDIS - EOS Data and Information System

GSFC - Goddard Space Flight Center

Gsw - Stomatal conductance

Hs - Relative humidity at leaf surface

IRGA - Infrared Gas Analyzer

LW - Long-wave radiation

NASA - National Aeronautics and Space Administration

NSA - Northern Study Area

OA - Old Aspen

OBS - Old Black Spruce

OJP - Old Jack Pine

ORNL - Oak Ridge National Laboratory

PANP - Prince Albert National Park

PAR - Photosynthetically Active Radiation

PFD - flux density of photosynthetically active radiation (PAR)

PFD-PAR - Flux Density

Pn - net photosynthetic rate

P0 - Atmospheric pressure

rbw - Boundary layer resistance

RSS - Remote Sensing Science

SSA - Southern Study Area

SW - Short-wave radiation

Ta - Ambient temperature

TE - Terrestrial Ecology

Tl - Leaf temperature

URL - Uniform Resource Locator

YA - Young Aspen

YJP - Young Jack Pine site

20\. Document Information

20.1 Document Revision Date

Written: 23-Jul-1996

Last Updated: 05-Jun-1998

20.2 Document Review Date

BORIS Review: 04-Feb-1997

Science Review: 20-May-1998

20.3 Document ID

20.4 Citation

List in acknowledgments:

Dr. Joseph A. Berry, Carnegie Institution of Washington, Stanford, CA
94305

Dr. G. James Collatz, Code 923, NASA GSFC, Greenbelt, MD 20771

Dr. John Gamon, Department of Biology, CSU\--LA, Los Angeles, CA 90032

Dr. Wei Fu, Carnegie Institution of Washington, Stanford, CA 94305

Dr. Art Fredeen, Fac. of Natural Resources and Environmental Studies,
University of N.B.C., Prince George, B.C., Canada

20.5 Document Curator

20.6 Document URL

Keywords

gas exchange

transpiration

respiration

atmospheric pressure

boundary layer resistance

ambient water vapor pressure

ambient CO~2~ concentration

ambient temperature

flux density of photosynthetically active radiation (PAR)

short-wave radiation

long-wave radiation

leaf temperature

CO~2~ concentration at leaf surface

relative humidity at leaf surface

CO~2~ concentration in intercellular air spaces

net photosynthetic rate

stomatal conductance

transpiration rate