The BOREAS Information System
1.1 Data Set Identification
Light/N profile data.
1.2 Data Set Introduction
1.3 Objective/Purpose
The purpose of this project was to quantify the relationship between percent
PAR levels and leaf nitrogen of three boreal forest tree species, black
spruce, jack pine and aspen at the BOREAS Northern Study Area.
1.4 Summary of Parameters
Downwelling photosynthetically active radiation (PAR), FPAR, leaf nitrogen
(N) concentration, specific leaf nitrogen (N) (i.e. N per unit leaf area)
1.5 Discussion
Functional convergence predicts that the investment into leaf nitrogen is
limited by the amount of available light (PAR) which in turn determines
photosynthetic capacity. This study tests this hypothesis through
measurements of the relationship between FPAR, PAR and N.
The downwelling radiation data from the northern study area (NSA) of the
BOREAS study area were collected to characterize the fpar levels at
different canopy levels of six boreal canopy cover types: young jack pine,
old jack pine, young aspen, old aspen, old (lowland) black spruce and upland
TE black spruce. Leaf samples were harvested at each light level, in order
to quantify specific leaf nitrogen content by leaf/needle age class.
Radiation data were collected between May 27, 1994 and September 17, 1994.
1.6 Related Data Sets
There will be a data file that summarizes the data for each sampling site
(6) per field campaign. Data for each transfer are in separate files.
2.1 Investigator(s) Name and Title
Hank Margolis
Ph.D. Universite Laval
Faculte de foresterie et geomatique
Pavillon Abitibi-Price
Sainte-Foy, Quebec
G1K 7P4 Canadatel.
(418) 656-7120
Email: Hank.margolis@sbf.ulaval.ca
2.2 Title of Investigation
Relationship between FPAR and leaf nitrogen for black spruce, jack pine and
aspen stands at the BOREAS Northern Study Area.
2.3 Contact Information
Marie R. Coyea, Ph.D. Universite Laval Faculte de foresterie et geomatique Pavillon Abitibi-Price Sainte-Foy, Quebec G1K 7P4 Canadatel (418)656-2131, poste 6546 Email Marie.Coyea@sbf.ulaval.ca
The photosynthetically active radiation measurements were obtained by point
quantum sensors. Data was relayed to a data acquisitionsystem (CR10) for
storage and data manipulation prior to downloading.
The methodology for measuring leaf area has been described in Appendix K of
the BOREAS Experiment Plan, version 3.0. Aspen foliagehas been expressed as
hemi-surface area leaf area, while conifer foliage has been expressed as
total surface area leaf area.
Kjeldahl procedures will be used to measure leaf nitrogen.
4.1 Sensor/Instrument Description
Point quantum sensors, millivolt adaptors; extension cables, BNC connectors
(LI-COR)
Data acquisition system (CR10 measurement and control module with wiring
panel and 12 volt power supply, CR10 keyboard and display, sc12 cable,
datalogger support software, CR10 manual, screwdrivers, sc532 data transfer
interface, data storage module (SM192), Campbell Scientific)
LadderExtendible pruning shears2 extendible support polespolyethylene
storage bagsfreezer spacedrying ovenoptical image analysis system (AgVision, Decagon Inc.)top loading weighing balance.
Laboratory equipped for Kjeldahl N analysis
4.1.1 Collection Environment
4.1.2 Source/Platform
A quantum sensor was supported at the top of a pole that was extended to
different levels in the canopy, following a vertical profile from the top of
the canopy to the groundcover and understory shrubs. These levels were
variable depending on the type of understory vegetation and the canopy
profile. One point quantum sensor was used to obtain simultaneous 100% light
readings. This sensor was placed on a pole extended from a canopy access
tower or a pole that was extended sufficiently above the tree canopy level
to avoidany shading during the sampling period. The data acquisition system
was kept at the sampling level while using canopy access towers, or on the
ground.
4.1.3 Source/Platform Mission Objectives
(As outlined in the Experiment Plan, Version 3, Appendix N, page N-34)
To examine the relationship betweeen net photsynthetic (net Ps) capacity, N
concentration and percent photsynthetically active radiation of three major
boreal forest cover types (jack pine, black spruce and aspen) as well as
their link to remotely-sensed and land-based measures of reflected and
absorbed radiation.
To establish general relationships which can be used to predict the vertical
distribution of the net Ps capacity for these cover types, including their
understories, when neither water nor temperature is greatly limiting.
4.1.4 Key Variables
PAR, FPAR, and N.
4.1.5 Principles of Operation
A quantum sensor under full sky exposure was set out under cloudy (diffuse)
sky conditions in each stand type. A second quantum sensor was moved
vertically throughout the canopy profile starting at ground level.
Vegetation at each light harvesting level was removed in order to determine
specific N content.
LI-COR quantum sensors measure photosynthetically active radiation (PAR) in
the 400 to 700 nm wave band. The unit of measurements ismicromoles per
second per square meter (umol/s/m2). The quantum sensor is designed to
measure PAR received on a plane surface. The indicated sensor response
corresponds to the expected photosynthetic response of plants for which data
is available. A silicon photodiode with an enhanced response in the visible
wavelengths is used as the sensor. A visible bandpass interference filter in
combination with coloured glass filters is mounted in a cosine corrected head.
Quantum sensors were connected to a data acquisition system. This system
(CR10) was programmed to convert a differential voltage measurement (rather
than a single ended measurement because of noise reduction) to a radiation
value. Each quantum sensor has a different calibration constant provided by
the manufacturing company that must be incorporated into the programming of
the CR10.
The CR10 is a fully programmable datalogger/controller that permits a user
to convert electronic responses of a sensor to comprehensible information
about our physical environment (e.g. temperature, radiation). It allows the
user to store data and program the retrieved data.
The AgVision System is an image analysis system that works by first looking
at an object through a video camera, then processing theimage into discrete
numerical information with a digitizer and microcomputer, and finally
displaying the image or other informationon a monitor for examination.
The Kjeldahl method, the most common method for nutrient analysis, will be
used for measuring total N.
4.1.6 Sensor/Instrument Measurement Geometry
Quantum sensors were pointed face up to the canopy (zenith angle) to obtain
downwelling radiation.
4.1.7 Manufacturer of Sensor/Instrument
Point quantum sensors Li-190SA, millivolt adaptors; extension cables,
BNC connectors:
LI-COR inc.CR10 data acquisition system CR10 measurement and control module with wiring panel and 12 volt power supply, cr10 keyboard and display, sc12 cable, datalogger support software, cr10 manual, screwdrivers, sc532 data transfer gadget, data storage module (SM192):
4421 Superior Street
P.O. Box 4425
Lincoln, NE. 68504 USA
tel. 1-800-447-3576
Campbell Scientific Canada Corp.Leaf area measurement system/Optical Image Analysis System (AgVision, Monochrome system, root and leaf analysis)
11564 149 Street
Edmonton, Alberta
Canada T5M 1W7
tel. 403-454-2505
Decagon Devices, Inc.
P.O. Box 835
Pullman, Washington 99163 USA
tel. 1-800-755-2751
4.2 Calibration
Quantum sensors that were used in the field were brand new. Calibration was
completed by the manufacturing company, and recalibration of radiation
sensors is normally recommended every two years. The calibration data is
unique to each sensor and so this was incorporated into the programming when
connected to a data acquisition system.
Prior to the season's field sampling, all quantum sensors were compared to
confirm that no differences in measurements existed. This involved comparing
radiation readings from the same light source. Following a comparison of
electrical environmental conditions (outside a building versus inside the
photosynthetic lab), a differential mode configuration rather than a single
ended voltage configuration was found to reduce response fluctuations (due
to electrical noise primarily). Therefore, the differential mode programming
and wiring set up were used. In the field, a quick comparison among quantum
sensors under similar light conditions was made.
The optical image analysis system was calibrated according to instrument
specifications each time the system was opened or after it was left for a
period of time. A fine ruler and flat disks of known area were used in the
calibration.
Calibration of Kjeldahl instrumentation is unknown at this time.
4.2.1 Specifications
The quantum sensors had a resolution capability of 1 umol m-2 s-1. The
absolute calibration is +/- 5% traceable to the US National Institute of
Standards and Technology.
The weighing balance was accurate to within 0.0001 g.
The leaf area system was accurate to within 1%.
The shape factor used for black spruce leaf area measurements was 4,
according to the BOREAS Experiment Plan, appendix K, Version 3). 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).
Specifications of Kjeldahl instrumentation is unknown at this time.
4.2.1.1 Tolerance
The acceptable range for our radiation measurements is between 0 and 2000
umol m-2 s-1. The quantums are typically sensitive to 8 uA per 1000 umol m-2
s-1. There is a maximum deviation of 1% up to 10,000 umol/s/m2.
4.2.2 Frequency of Calibration
Field checks of quantum sensor readings were carried out upon installation
of the quantums and everytime data was transferred.
Quantum sensor calibration was completed by the manufacturing company, and
recalibration of radiation sensors is normally recommended every two years.
4.2.3 Other Calibration Information
Information regarding calibration for N analysis using the Kjeldahl method
is unavailable at this time.
Downwelling radiation data for the northern study area (NSA) of the BOREAS study area were collected to characterize the vertical profile of fpar (the fraction of above canopy PAR) of six boreal forest canopy cover types: young jack pine, old jack pine, young aspen, old aspen, old (lowland) and upland black spruce. These data were collected during diffuse light conditions (overcast/cloudy days) during the three field campaigns between May 27, 1994 and September 17, 1994.
For each stand, the following activities took place:
LA = SF x sqrt(VL)
Where: LA = leaf area, SF = shape factor, V = volume of needles, L = total length of needles
In the case where only a subsample of needles is used, the equation becomes:
LA = SF x sqrt(Vnl)
Where: LA = leaf area, SF = shape factor, V = volume of needles, l = average length of needles (20), n = total number of needles
6.1 Data Notes
6.2 Field Notes
None at this time.
7.1 Spatial Characteristics
The data was collected from 6 principal sites in the northern study area
(NSA) of Manitoba. The NSA is approximately 100 km by 80 km, and is located
735 km north of Winnipeg. The principal sites in this study were:
Quantum sensors (on poles) were used on the canopy access towers in the bottom, middle and top canopy. In the case of the young jack pine site, where a canopy access tower did not exist, sensors were located within 1 km of the flux tower.
7.1.1 Spatial Coverage
Data acquisition at all six sites was repeated for each of the three
intensive field campaigns. The overall period extended from May 24 to September 17, 1994.
7.1.2 Spatial Coverage Map
7.1.3 Spatial Resolution
During the first IFC, the following sites were measured: YJP, May 29; OJP, May 31; YASP, June 14; OASP, June 12; OBS, June 12; TE-BS, June 3.
During the second IFC, the following sites were measured:YJP, July 24; OJP,
July 19, 20; YASP, July 26,30; OASP, July 21, 24; OBS, July 25; TE-BS, July 22, 23.
During the third IFC, the following sites were measured: YJP, September 8,
11, 12; OJP, September 5, 6; YASP, September 8,11; OASP, September 2, 5, 6; OBS, September 13;TE-BS, September 12.
7.1.4 Projection
7.1.5 Grid Description
7.2 Temporal Characteristics
7.2.1 Temporal Coverage
7.2.2 Temporal Coverage Map
7.2.3 Temporal Resolution
7.3 Data Characteristics
7.3.1 Parameter/Variable
See 7.3.4.
7.3.2 Variable Description/Definition
1 = Young Jack Pine flux tower site2 = Old Jack Pine flux tower site3 = Young Aspen site4 = Old Aspen site (canopy access tower only)5 = Old Black Spruce flux tower site6 = TE Black Spruce site (canopy access tower only)
7.3.3 Unit of Measurement
See 7.3.2.
7.3.4 Data Source
Second #
1 = top of canopy
2 = middle of canopy
3 = bottom third of canopy
4 = at understory level (below crown canopy)
5= at ground cover level
When a level 6 exists, this corresponds to measurements taken at ground cover, and level 5 corresponds to measurements taken just above a second understory canopy level, i.e. another level of sampling had been added in, always in vertical profile order.
7.3.5 Data Range
Not avaialble at this time.
7.4 Sample Data Record
species site ifc stid age logPAR nitrogen(mg/g) PAR(%) nitrogen(gN/m2) aspen oasp ifc1 4101 current 4.514 27.59 91.29 1.5
8.1 Data Granularity
8.2 Data Format(s)
The data has been saved using Microsoft Excel (Version 5.0 for IBM) in text
format.
9.1 Formulae
FPAR (%)=((PAR at 100% exposure - PAR reading below canopy)/PAR at 100%
exposure)*100. For example, if the maximum PAR (no shading)was 890 and the
PAR value underneath canopy was 230, then FPAR under the canopy = 74.16% =
((890-230)/890) x 100
9.1.1 Derivation Techniques and Algorithms
None at this time.
9.2 Data Processing Sequence
9.2.1 Processing Steps
Data from quantum sensors was first converted from electrical (voltage) data
to a radiation value in a program (given by the user) for the CR10. This
program is specific to this data acquisition system. See the manual for
programming if you want to learn how to program (Campbell Scientific).
Each minute the CR10 was programmed to take the data which was being
retrieved every second, and do the following:
All raw data was printed. Column headings were inserted. Subsequently, all
lines that were not part of the sampling scheme were erased. A code that had
been entered into the CR10 program in place of the site location enabled us
to identify when the relevant light data was not being taken. This code was
normally 1.2 and has no other meaning other than to signify that the light
values at this time are not useful. For example, the sensor may at this time
have been between two different light levels.Lines that contained zero readings for the quantum sensors were erased
(using the autofilter function in Excel, version 5.0). Where only 1 minute
or less of data existed per level, these lines were not removed (to avoid
blank data cells) Data was then sorted in order of the light profile. Light
readings by minute for a level were then averaged together (using the
subtotals function in Excel,version 5.0), so that at each change in SITEID
the function AVERAGE was used to subtotal all the columns of data.%PAR and FPAR values were calculated. Year and cdate (calendar date) were
inserted as columns.Manitoba time data was converted from a numeric format to a time format
(because original data was in numeric format). The following command was
used in Excel, version 5 to do this step:
time(mid(a1;1;len(a1)-2);right(a1;2);0). Where a1 refers to the data cell
where the time data was found. This value may be f1, for example, depending
on what column the data was found. Manitoba time was then converted to
Greenwich Mean Time = Thompson, Manitoba time + 6 hours.Shoot silhouette data, specific leaf area and leaf area data were then
transferred into the data files. (At this point there is only one line of
data for each desired light level). Data was then checked with original data
sheets.Note that the SLA samples corresponding to the YJP stand in IFC 1 (May 29, 1994) were either misplaced, ground or lost. In order tocompensate for this
lost SLA data, the SLA data from the photosynthesis data (May 27, group
TE-9B), were substituted. The SLA represent the same sampling levels, but
only 4 repetitions were available for this set. Photosynthesis was measured
on 3 branches at each canopy level for 5 yjp trees. An average sla (based on
3 branches for each canopy level) was used.
9.2.2 Processing Changes
See 9.2.1.
9.3 Calculations
See 9.1.
9.3.1 Special Corrections/Adjustments
None at this time.
9.3.2 Calculated Variables
9.4 Graphs and Plots
None submitted.
10.1 Sources of Error
If the wiring to the CR10 is not fixed securely, loose wires can lead to
dubious data results. Likewise if wires have been chewed up by rodents or by
hungry canopy tower people, results may be questionable. We had no evidence
of these activities during the field season.
If the battery charge is below 9.6 volts, we can expect errors in the data
set. We checked for this in our data set, but it is doubtful that this
happened since at every data transfer in the field this value was checked.
We can expect errors in the data set when the CR10 module temperature is
greater than 50 C. We checked for this in our data set. However, despite the
warm and dry conditions that were experienced this summer, it was unlikely
that this everoccurred. The storage module was placed in a shady understory
location.
10.2 Quality Assessment
10.2.1 Data Validation by Source
All possible errors were checked and removed.
10.2.2 Confidence Level/Accuracy Judgement
Data are preliminary. Pease contact us if used for publication.
10.2.3 Measurement Error for Parameters
Not available at this time
10.2.4 Additional Quality Assessments
None at this time.
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
Not available at this time.
11.3 Usage Guidance
Not available at this time.
11.4 Other Relevant Information
Not available at this time.
14.1 Software Description
14.2 Software Access
15.1 Contact Information
Marie R. Coyea, Ph.D.
Universite Laval
Faculte de foresterie et geomatique
Pavillon Abitibi-Price Sainte-Foy,
Quebec G1K 7P4 Canadatel.
(418) 656-2131, poste 6546
Email: coyeamar@vm1.ulaval.ca
15.2 Data Center Identification
None.
15.3 Procedures for Obtaining Data
Users may place requests by letter, telephone, electronic mail, fax or
personal visit. If the data is taken from BORIS, discussions with either
Marie Coyea or Hank Margolis should definitely take place before using the data.
15.4 Data Center Status/Plans
16.1 Tape Products
16.2 Film Products
16.3 Other Products
Bremner, J.M. and Mulvaney, C.S. 1982. Nitrogen-total. pp. 595-624. In Page, A.L., Miller, R.H. and Keeney, D.R. (eds.). Methods of Soil Analysis - Part 2. Chemical and microbiological properties (2e ed.). Agron. No. 9. ASA-SSSA, Madison, Wisconsin
17.1 Platform/Sensor/Instrument/Data Processing Documentation
Campbell Scientific Canada Corp. 1992. CR10 measurement and control module
operator's manual. Revision 3-31-92. Edmonton, Alberta.
Decagon Devices Inc. 199? AgVision monochrochrom system, root and leaf analysis, operator's manual. Pullman, Washington, USA.
LI-COR, inc. 1991. LI-COR Radiation sensors instruction manual. Publication No. 8609-56. Lincoln, Nebraska, USA.
17.2 Journal Articles and Study Reports
Q.L. Dang, H. Margolis, M.R. Coyea, M. Sy, G.J. Collatz and C. Walthall
1996. 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 (accepted with minor
revision, July 29, 1996).
17.3 Archive/DBMS Usage Documentation
BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System DAAC - Distributed Active Archive Center EOS - Earth Observing System EOSDIS - EOS Data and Information System FPAR - Fraction of photosynthetically active radiation GSFC - Goddard Space Flight Center IPAR - Intercepted PAR NASA - National Aeronautics and Space Administration OASP - Old aspen canopy access tower site OJP - Old jack pine flux tower site ORNL - Oak Ridge National Laboratory PAR - Photosynthetically active radiation PARFPAR - Fraction of absorbed Ps - Photosynthesis TE-BS - Terrestrial ecology black spruce canopy access tower site URL - Uniform Resource Locator YJP - Young jack pine flux tower site
20.1 Document Revision Date
26-August-1996.
20.2 Document Review Date(s)
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)
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