The BOREAS Information System
This data set describes the relationship between foliage nitrogen concentration and photosynthetic capacity in the canopies of NSA-OBS, NSA-UBS, NSA-OJP, NSA-YJP AND NSA-OASP at the NSA.
This data set describes the relationship between foliage nitrogen concentration and photosynthetic capacity in the canopies of NSA-OBS, NSA-UBS, NSA-OJP, NSA-YJP AND NSA-OASP at the NSA.
1.1 Data Set Identification
Relationships between Photosynthetic Capacity and Nitrogen Concentration
at the NSA.
1.2 Data Set Introduction
The canopy profiles of nitrogen concentration and photosynthetic capacity
were examined as part of our efforts to characterize the spatial and
temporal variations in photosynthetic capacity and nitrogen allocation in
the boreal forest. This information will be useful for modelling the
vertical distribution of carbon fixation for different forest types in
the
boreal forest. Samples were taken from six forest types in the NSA:
NSA-OBS,
NSA-UBS, NSA-OJP, NSA-YJP AND NSA-OASP during each of the three intensive
field campaigns in 1994.
Measurements were taken under controlled environmental conditions in the
laboratory. We used an open gas exchange system in differential mode for
measuring the photosynthetic capapcity.
1.3 Objective/Purpose
This data set was collected and prepared to provide the profile of
photosynthetic capacity and nitrogen concentration in the forest canopy
of NSA-OBS (Picea mariana (Mill.), NSA-UBS (Picea mariana (Mill.),
NSA-OJP (Pinus banksiana Lamb.), NSA-YJP AND NSA-OASP (Populus
tremuloides Michx.) in the Northern Study Area. This information will
also be useful for modelling the vertical distribution of carbon fixation
for different forest types in the boreal forest.
1.4 Summary of Parameters
Light-saturated net photosynthesis, nitrogen concentration
1.5 Discussion
The canopy profiles of nitrogen concentration and photosynthetic capacity
were examined as part of our efforts to characterize the spatial and
temporal variations in photosynthetic capacity and nitrogen allocation in
the boreal forest. This information will be useful for modelling the
vertical distribution of carbon fixation for different forest types in
the
boreal forest. Samples were taken from six forest types in the NSA:
NSA-OBS,
NSA-UBS, NSA-OJP, NSA-YJP AND NSA-OASP during each of the three intensive
field campaigns in 1994.
Measurements were taken under controlled environmental conditions in the
laboratory. We used an open gas exchange system in differential mode for
measuring the photosynthetic capapcity.
1.6 Related Data Sets
Photosynthetic response of boreal tree species to light at the
NSA.Photosynthetic response of boreal tree species to vapor pressure
deficit
at the NSA.Photosynthetic response of boreal tree species to CO2 at the
NSA. Photosynthetic response of boreal tree species to temperature at the
NSA. Photosynthetic response of boreal tree species to shoot water
potential
at the NSA.
2.1 Investigator(s) Name and Title
Dr. Hank Margolis, Associate Professor
2.2 Title of Investigation
Canopy Profiles of Photosynthetic Capacity and Nitrogen Concentration at
the NSA.
2.3 Contact Information
Dr. Hank Margolis Universite Laval Faculte de foresterie et de geomatique Pavillon Abitibi-Price Sainte-Foy, Quebec G1K 7P4 Canada Telephone (418) 656-7120 E-mail: Hank.margolis @sbf.ulaval.ca Dr. Qinglai Dang Lakehead University Faculty of Forestry 955 Oliver Road, Thunder Bay Canada P7B 5E1 Telephone: 807-343-8507 Fax: 807-343-8116 E-mail: Qinglai.Dang@flash.lakeheadu.ca
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The total nitrogen concentration of foliage was determined by the
Kjeldahl
method. This consists of two main steps: (1) The nitrogen in the sample
is
converted to NH4+ N by digestion with concentrated H2SO4 containing
substances that promote this conversion. (2) The NH4+ N is determined
from
the amount of NH3 liberated by distillation of the digest with alkali.
This
is a common procedure for total nitrogen determination for plant
materials.
4.1 Sensor/Instrument Description
LI-COR-6262 infra-red gas analyzer, thermocouples, balance, Decagon
AgVision
Root and leaf analysis system, LI-COR quantum PAR sensor.
4.1.1 Collection Environment
The vertical profile of the canopy was divided into three layers; top,
middle and bottom. For old black spruce, upland high-productivity (TE)
black
spruce and old jack pine, all three layers were of the same species. In
the
young jack pine, the bottom layer was the understory black spruce
seedlings,
while the top and middle layers were jack pine. In the old aspen, the
bottom
layer was alder while the top and middle layers were aspen. Branch
samples
were harvested from each layer and were immediately re-cut under water.
The
samples were then transported back to the laboratory for gas exchange
measurements. The cut-surface of the branch was submerged in water during transport and in the laboratory.
Samples were cut in the dark. The samples that were about to be measured, however, were exposed to saturated light for two hours before the
beginning
of the measurements to induce stomatal opening and photosynthetic
activity.
To keep a continual supply of water to the branch, the cut surface was in contact with water during the entire period. The light source was two 1000-watt high pressure sodium lamps. Different levels of light was
achieved
by using different neutral density filters. The environmental conditions
inside the leaf cuvette were as follows: temperature 20 +/- 0.5 C; vapor
pressure deficit 0.7 +/- 0.2 kPa; CO2 360 +/- 20 ppm.
Photosynthesis and related parameters are all expressed on a hemi-surface area basis. The shape factors the leaf area calculation were 4 and 4.59,
respectively, for black spruce and jack pine.
4.1.2 Source/Platform
Branch samples were taken using a shotgun and were re-cut under water.
Photosynthesis was measured in the laboratory under controlled
environment.
4.1.3 Source/Platform Mission Objectives
4.1.4 Key Variables
Rate of light-saturated net photosynthesis, foliar nitrogen concentration
4.1.5 Principles of Operation
Eight samples were measured from each canopy level. Two samples were
measured at a time and the measurement proceeded alternating between
different canopy levels.
4.1.6 Sensor/Instrument Measurement Geometry
Samples were all taken from the upper third of the forest canopy.
Efforts were made to keep the amount of foliage relatively consistent
from sample to sample. The leaf chamber for the measurement is about
1300 cubic inch.
4.1.7 Manufacturer of Sensor/Instrument
LI-6200 portable gas exchange system LI-COR P.O.Box 4425, 4421 Superior St., Lincoln, NE 68504 USA, tel. 1-800-447-3576 Leaf area measurement system/Optical Image Analysis System (AgVision, Monochrome system, root and leaf analysis) Decagon Devices, Inc. P.O. Box 835 Pullman, Washington 99163 USA,tel. 1-800-755-2751
4.2 Calibration
The gas analyzer was calibrated against standard gas which was calibrated
against the prime CO2 standard in the NSA lab in Thompson. Calibration
was
done at the beginning of each field campaign.
4.2.1 Specifications
The weighing balance was accurate to within 0.0001 g.
The leaf area system was accurate to within 1%.
The gas exchange system was accurate to 1 ppm CO2.
The shape factor used for black spruce was 4, as according to the BOREAS
Experiment Plan, appendix K, Version 3.0). Based on observations of two
cross sections of two needles per fascicle for five fascicles for six
jack pine trees from Thompson, Manitoba, we calculated an average shape
factor of 4.59 (+/- 0.07).
4.2.1.1 Tolerance
No tolerance level was set for these measurements.
4.2.2 Frequency of Calibration
LI-COR 6262 IRGA was calibrated at the beginning of each IFC.
4.2.3 Other Calibration Information
The vertical profile of the canopy was divided into three layers; top,
middle and bottom. For old black spruce, upland high-productivity (TE)
black
spruce and old jack pine, all three layers were of the same species. In
the
young jack pine, the bottom layer was the understory black spruce
seedlings,
while the top and middle layers were jack pine. In the old aspen, the
bottom
layer was alder while the top and middle layers were aspen. Branch
samples
were harvested from each layer and were immediately re-cut under water.
The
samples were then transported back to the laboratory for gas exchange
measurements. The cut-surface of the branch was submerged in water during
transport and in the laboratory.
Samples were cut in the dark. The samples that were about to be measured,
however, were exposed to saturated light for two hours before the
beginning
of the measurements to induce stomatal opening and photosynthetic
activity.
To keep a continual supply of water to the branch, the cut surface was in
contact with water during the entire period. The light source was two
1000-watt high pressure sodium lamps. Different levels of light was
achieved
by using different neutral density filters. The environmental conditions
inside the leaf cuvette were as follows: temperature 20 +/- 0.5 C; vapor
pressure deficit 0.7 +/- 0.2 kPa; CO2 360 +/- 20 ppm.
Photosynthesis and related parameters are all expressed on a hemi-surface
area basis. The shape factors the leaf area calculation were 4 and 4.59,
respectively, for black spruce and jack pine.
6.1 Data Notes
6.2 Field Notes
Samples were taken between 6 and 7 am from one site per day over five
days.
See pages 2-23 and 2-24 in the BOREAS Experiment Plan Version 3.0 for a
description of
site conditions.
7.1 Spatial Characteristics
Branch samples were taken from four different trees from each site and
those
trees were at least 10 m apart from each other.
7.1.1 Spatial Coverage
Four trees at least 10 m apart from each other were sampled at each site.
The location of each site is as follows:
7.1.2 Spatial Coverage Map
Four trees at least 10 m apart from each other were sampled at each site.
The location of each site is as follows:
7.1.3 Spatial Resolution
Not applicable.
7.1.4 Projection
Not Applicable.
7.1.5 Grid Description
Not Applicable.
7.2 Temporal Characteristics
7.2.1 Temporal Coverage
Samples were taken between 6 and 7 am. Measurements in the lab normally
took 8 to 14 hours. An independent data set was taken at each of the three field
campaigns 1994. The specific dates for each measurement are given in the
data table.
7.2.2 Temporal Coverage Map
Site Sample Dates (month-day); 1994 NSA-OBS 6-9, 7-21, 9-4 NSA-UBS 6-6, 7-22, 9-1 NSA-OJP 6-2, 7-19, 8-31 NSA-YJP 6-5, 7-23, 9-2 NSA-OASP 6-7, 7-21, 9-3
7.2.3 Temporal Resolution
Not Applicable.
7.3 Data Characteristics
7.3.1 Parameter/Variable/definition/unit
Variable Description Unit A Photsynthetic capacity umol/m2/s N% Percent nitrogen concentration % N g/m2 nitrogen per unit hemi-surface area g/m2 N mg/g nitrogen per dry mass of foliage mg/g
7.3.4 Data Source
7.3.5 Data Range
7.4 Sample Data Record
species site IFC photosynthesis N% N g/m2 N mg/g ojp old ifc1 2.9 0.808 1.57 8.08
8.1 Data Granularity
(BORIS and ORNL DAAC to fill in)
8.2 Data Format(s)
Record 1 variables Record 2 1st observation Record n (n-1)th observation
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9.1 Formulae
9.1.1 Derivation Techniques and Algorithms
Photosynthetic capacity was calculated according to von Caemmerer and
Farquhar (1981) Planta 153: 376-387.
9.2 Data Processing Sequence
9.2.1 Processing Steps
Data were recorded automatically by a computer and also printed on a
printer. Subsequent calculations of different parameters were performed
on MS Excel for Windows 5.0.
9.2.2 Processing Changes
None.
9.3 Calculations
Photosynthetic capacity was calculated according to von Caemmerer and
Farquhar (1981) Planta 153: 376-387.
9.3.1 Special Corrections/Adjustments
None
9.3.2 Calculated Variables
Photosynthetic capacity was calculated according to von Caemmerer and
Farquhar (1981) Planta 153: 376-387.
9.4 Graphs and Plots
Photosynthetic capacity versus N.
10.1 Sources of Error
None.
10.2 Quality Assessment
Data are preliminary. Please contact us if used for publication.
10.2.1 Data Validation by Source
A base measurement (i.e. when the cuvette contains no samples) was taken
both before and after each set of measurements. Other measurements
wereadjusted by the base values, if necessary.
10.2.2 Confidence Level/Accuracy Judgement
No statistical confidence level is available, but we feel that these data are reliable.
10.2.3 Measurement Error for Parameters
None
10.2.4 Additional Quality Assessments
Calculated results were plotted and the patterns were examined and
compared
with the literature. Outliers (determined visually) were eliminated from
the data set.
10.2.5 Data Verification by Data Center
(For BORIS and ORNL DAAC Use)
11.1 Limitations of the Data
11.2 Known Problems with the Data
None.
11.3 Usage Guidance
None.
11.4 Other Relevant Information
None.
None
14.1 Software Description
Calculations were performed using MS Excel for Windows 5.0. This
document was prepared using MS Word 6.0 for Windows.
14.2 Software Access
(This section for BORIS and ORNL DAAC Use)
15.1 Contact Information
See section 2.3.
15.2 Data Center Identification
15.3 Procedures for Obtaining Data
15.4 Data Center Status/Plans
16.1 Tape Products
None.
16.2 Film Products
None.
16.3 Other Products
None.
von Caemmerer, S. and Farquhar, G.D. 1981. Some relationships between biochemistry of photosynthesis and the gas exchange of leaves. Planta 153: 376-387.
Bremner, J.M. and Mulvaney, C.S. 1982. Nitrogen - Total. pp. 595-623. In:Methods of Soil Analysis, Part 2. Chemical and Microbiological Properties. Second edition. A.L. Page, R.H. Miller and D.R. Keeney, editors. AmericanSociety of Agronomy Inc. and the Soil Science Society of America Inc., Madison, Wisconsin.
17.1 Platform/Sensor/Instrument/Data Processing Documentation
Li-cor 6262 infra-red gas analyzer manual.
17.2 Journal Articles and Study Reports
Q.L. Dang, H. Margolis, M.R. Coyea, M. Sy, G.J. Collatz and C. Walthall
1997. Profiles of photosynthetically active radiation, nitrogen, and
photosynthetic capacity in the boreal forest: implications for scaling
from
leaf to canopy. J. Geophys. Res., BOREAS Special Issue (in press).
17.3 Archive/DBMS Usage Documentation
None.
BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System DAAC - Distributed Active Archive Center EOS - Earth Observing System EOSDIS - EOS Data and Information System GSFC - Goddard Space Flight Center NASA - National Aeronautics and Space Administration ORNL - Oak Ridge National Laboratory URL - Uniform Resource Locator A - Photsynthetic capacity (umol/m2/s) N% - percent nitrogen concentration (%) N g/m2 - nitrogen per unit hemi-surface area (g/m2) N mg/g - nitrogen per dry mass of foliage (mg/g) UBS - Upland Black Spruce (TE site) OBS - Old Black Spruce OJP - Old Jack Pine YJP - Young Jack Pine OASP - Old Aspen NSA - Northern Study Area
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20.1 Document Revision Date
Last updated 3-Dec-1996
20.2 Document Review Date(s)
(For BORIS and ORNL DAAC Use)
BORIS Review:
Science Review:
20.3 Document ID
(For BORIS and ORNL DAAC Use)
20.4 Citation
Please contact us.
20.5 Document Curator
(For BORIS and ORNL DAAC Use)
20.6 Document URL
(For BORIS and ORNL DAAC Use)
