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

Summary

The BOREAS TE-09 team collected several data sets related to chemical and 
photosynthetic properties of leaves in boreal forest tree species. This data set 
describes the relationship between Photosynthetically Active Radiation (PAR) 
levels and foliage nitrogen in samples from six sites in the BOREAS NSA. This 
information is useful for modeling the vertical distribution of carbon fixation 
for these different forest types in the boreal forest.  The data were collected 
to quantify the relationship between PAR and leaf nitrogen of black spruce, jack 
pine, and aspen.  The data are available in tabular ASCII files.

Table of Contents

   *  1.  Data Set Overview
   *  2.  Investigator(s)
   *  3.  Theory of Measurements
   *  4.  Equipment
   *  5.  Data Acquisition Methods
   *  6.  Observations
   *  7.  Data Description
   *  8.  Data Organization
   *  9.  Data Manipulations
   *  10. Errors
   *  11. Notes
   *  12. Application of the Data Set
   *  13. Future Modifications 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-09 PAR and Leaf Nitrogen Data for NSA Species

1.2 Data Set Introduction

The canopy profiles of nitrogen concentration and photosynthetic capacity were 
examined as part of an effort to characterize the spatial and temporal 
variations in photosynthetic capacity and nitrogen allocation in the boreal 
forest. This information will be useful for modeling the vertical distribution 
of carbon fixation for different forest types in the boreal forest. Samples were 
taken from six forest types in the BOReal Ecosystem-Atmosphere Study Area 
(BOREAS) Northern Study Area (NSA):  NSA-Old Black Spruce (OBS), NSA-Upland 
Black Spruce (UBS), NSA-Old Jack Pine (OJP), NSA-Young Jack Pine (YJP), NSA-
Young Aspen (YA) and NSA-Old Aspen (OA) during each of the three Intensive Field 
Campaigns (IFCs) in 1994. 

1.3 Objective/Purpose

The purpose of this project was to quantify the relationship between percent 
Photosynthetically Active Radiation (PAR) levels and leaf nitrogen of three 
boreal forest tree species, black spruce, jack pine, and aspen, at the BOREAS 
NSA.

1.4 Summary of Parameters

Downwelling PAR, transmitted PAR, 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 BOREAS NSA were collected to 
characterize the FPAR levels at different canopy levels of six boreal canopy 
cover types: YJP (Pinus banksiana), OJP, YA (Populus tremuloides), OA, OBS 
(Picea mariana), and UBS. 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 27-May-1994 and 17-Sep-1994. 

1.6 Related Data Sets

BOREAS TE-09 NSA Photosynthetic Response Data

BOREAS TE-09 NSA Photosynthetic Capacity and Foliage Nitrogen Data

2. Investigator(s)

2.1 Investigator(s) Name and Title

Hank Margolis, Ph.D.
Universite Laval
Faculte de foresterie et geomatique 

Marie R. Coyea, Ph.D.
Universite Laval
Faculte de foresterie et geomatique

2.2 Title of Investigation

Relationship between measures of absorbed and reflected radiation and the 
photosynthetic capacity of boreal forest canopies and understories.

2.3 Contact Information

Contact 1
----------------
Marie R. Coyea, Ph.D.
Universite Laval
Faculte de foresterie et geomatique
Pavillon Abitibi-Price Sainte-Foy,
Quebec
Canada
(418)656-2131, poste 6546
Marie.Coyea@sbf.ulaval.ca

Contact 2
----------------
Hank Margolis, Ph.D.
Universite Laval
Faculte de foresterie et geomatique 
Pavillon Abitibi-Price 
Sainte-Foy, Quebec 
Canada
(418) 656-7120
(418) 656-3551 (fax)
Hank.margolis@sbf.ulaval.ca

Contact 3
----------------
Shelaine Curd
NASA GSFC
Greenbelt, MD
(301) 286-2447
(301) 286-0239 (fax)
shelaine.curd@gsfc.nasa.gov

3. Theory of Measurements

The PAR measurements were obtained by point quantum sensors.  Data were relayed 
to a data acquisition system (CR10) for storage and data manipulation prior to 
downloading.

The methodology for measuring leaf area is described in Appendix K of the BOREAS 
Experiment Plan, Version 3.0.  Aspen foliage is expressed as hemisurface area 
leaf area, while conifer foliage is expressed as total surface area leaf area.

Kjeldahl procedures were used to measure leaf nitrogen.

See Section 5, Data Acquisition Methods, for further explanation.

4. Equipment

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).

Ladder, extendible pruning shears, two extendible support poles, polyethylene 
storage bags, freezer space, drying oven, optical image analysis system 
(AgVision, Decagon Inc.), top-loading weighing balance.

Laboratory equipped for Kjeldahl N analysis.

4.1.1 Collection Environment

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.  The particular weather 
conditions on each sampling day should be contained in the various BOREAS 
meteorological data.

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 incident 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 avoid any 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

The objective of the hand-held or tower supported pole was to hold the quantum 
sensor in place in order to make proper measurements.

4.1.4 Key Variables

Incoming PAR, FPAR, and foliar N concentration.

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 PAR in the 0.400-0.700 m wave band. The unit of 
measurements is micromoles per second per square meter mol/(m2.sec). 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 are 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 colored 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 the 
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 the image into discrete 
numerical information with a digitizer and microcomputer, and finally displaying 
the image or other information on a monitor for examination. This system was 
used for leaf area measurements.

The Kjeldahl method, the most common method for nutrient analysis, was 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. 
4421 Superior Street
P.O. Box 4425
Lincoln, NE 68504 
1 (800) 447-3576

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): 
Campbell Scientific Canada Corp.
11564 149 Street
Edmonton, Alberta
Canada  T5M 1W7
403-454-2505

Leaf area measurement system/optical image analysis system (AgVision,  
Monochrome system, root and leaf analysis)
Decagon Devices, Inc.
P.O. Box 835
Pullman, WA  99163 
1 (800) 755-2751

4.2 Calibration

4.2.1 Specifications

The quantum sensors had a resolution capability of 1 meter mol/(m2.sec).  The 
absolute calibration is +/- 5%, traceable to the U.S. National Institute of 
Standards and Technology (NIST).

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, in 
accordance with 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, an average shape 
factor of 4.59 (+/- 0.07) was calculated.

Specifications of Kjeldahl instrumentation are unknown at this time. 

4.2.1.1 Tolerance

The acceptable range for the radiation measurements is between 0 and 2, meter 
mol/(m2.sec). According to the company, the quantum sensors are typically 
sensitive to 8 A per 1,000 meter mol/(m2.sec) with a maximum deviation of 1% 
up to 10,000 meter mol/(m2.sec).

4.2.2 Frequency of Calibration

The quantum sensors used in the field were brand new. Calibration was completed 
by the manufacturing company, and recalibration of radiation sensors is normally 
recommended every 2 years. The calibration data are unique to each sensor and 
were incorporated into the programming when connected to a data acquisition 
system.

Field checks of quantum sensor readings were made upon installation of the 
sensors and every time data were transferred.

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 (caused 
primarily by electrical noise). Therefore, the differential mode programming and 
wiring setup 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. 

4.2.3 Other Calibration Information

None.

5. Data Acquisition Methods

Downwelling radiation data for the BOREAS NSA were collected to characterize the 
vertical profile of FPAR of six boreal forest canopy cover types: YJP, OJP, YA, 
OA, OBS and UBS. These data were collected during diffuse light conditions 
(overcast/cloudy days) during the three field campaigns between 27-May-1994 and 
17-Sep-1994.

For each stand, the following activities took place:

Vertical light profiles were established in each forest cover type based on five 
randomly chosen branches at five height levels (top, middle, and lower third of 
the crown; top of understory shrubs and top of groundcover.) Where there were 
two levels of understory shrubs; another level was taken into account. Sampling 
took place from the bottom up. That is, samples were harvested starting from the 
groundcover level before moving up vertically in order to avoid any effect on 
subsequent light measurements.

Light readings on cloudy days (diffuse light conditions) were obtained for each 
stand using a quantum sensor connected to a CR10 data acquisition system. A BNC 
connector and a millivolt adaptor (604 ohms) were connected to each sensor that 
was connected to the CR10 data measurement system. Quantum sensors were 
suspended for a minimum period of 2 minutes at each level just above a branch 
level that was subsequently harvested (input readings= 5 seconds, output 
readings = 1 minute). One quantum sensor was extended to obtain simultaneous 
readings of incident PAR. This sensor was placed on a pole extended either from 
a canopy access tower or sufficiently above the tree canopy level to avoid any 
shading during the measurement period. This made it possible to calculate where 
100% FPAR is complete interception, or darkness, and 0% is completely exposed 
and equal to the incident PAR.

For the radiation measurements in the canopy, one person leaned over the canopy 
access tower holding a pole with the quantum sensor attached at the end, while 
another person manipulated the CR10 at the same level. Following each 
measurement level, the light readings were transferred directly to a storage 
module. 

FPAR was calculated for each measurement point. 

The radiation measurements were based on a total of two point-quantum sensors 
(one taking the canopy profile and one at full light) that were relayed to the 
CR10. All quantum sensors were connected to the same CR10 for simultaneous 
measurements. Consequently, it was possible to calculate FPAR.  Sensor readings 
were taken every 10 seconds, while output measurements were based on 5-minute 
intervals. 

A branch at each light level was cut using a set of extendible pruning shears. 
These samples were used for N measurements. On conifer trees, these samples 
included the most recent year's needle growth and at least 2 years of previous 
needle growth. Branches for N analysis were stored in identified polyethylene 
bags for transport. These samples were stored in a freezer until time for 
further manipulation was available. A subsample of these branches was cut in 
order to determine specific leaf area (SLA). The remaining branches were oven-
dried for 48 hours at 688C, after which the lignified material was separated 
from the foliage tissue. The foliage tissue was then ground to 1mm and stored in 
sealed plastic containers until %N was quantified.

The material was oven-dried again and weighed 2 hours prior to N analysis. At 
least 200 mg of dried material was necessary for each N analysis. The Kjeldahl 
method was used to estimate nitrogen concentration. Nitrogen is expressed both 
on a SLA and a weight basis.

SLA was measured for each conifer leaf sample, by age class, using the volume 
displacement method to measure half the area of the surface of the leaf (HASL). 
An optical image analysis system (Decagon) was also used to measure shoot 
silhouette area and projected leaf area. For flat surfaces, such as aspen 
leaves, the hemisurface area is the same as both the projected area and 
silhouette area. The silhouette area of conifer samples was measured by age 
class. (In the first IFC, however, there was only one age class). A conifer 
shoot was first snipped and clipped into two age classes: (1) 1994 needles, and 
(2) anything produced in 1993 or before.  Each shoot section was then randomly 
thrown under the camera lens and a silhouette measurement was taken. These 
samples were then processed under the normal procedures for measuring leaf area 
(volume displacement). 

In order to conduct the volume diplacement method for measuring conifer leaf 
area, a container large enough for an intact shoot to be submerged filled with a 
solution of water and about 3-5% detergent. The detergent is necessary because 
it prevents small air bubbles and films from accumulating on the surface of the 
shoot. The container has to be large enough for the shoot to be submerged 
without touching the walls of the container. The container and liquid are placed 
on a top-loading electronic balance and tared to provide a zero reading. An 
intact shoot is submerged in the liquid without touching the walls of the 
container, and the weight is recorded. To push the shoot into the water, a force 
equal to the buoyant force must be applied. The buoyant force is related to the 
mass of the volume of water displaced by the shoot. Thus, the volume of the 
intact shoot in cubic centimeters is numerically equal to the weight increase in 
grams indicated on the balance. The length of these needles is determined. If 
measuring all the needles is too time-consuming, the number of needles on the 
shoot is counted, and a subsample of 10 to 20 needles spaced over the length of 
the shoot is used. The needles are then removed from the shoot, and the volume 
of the woody portion of the shoot is measured by submerging it in the liquid-
filled container on the balance. The needle volume is the difference between the 
total volume and the woody volume. 

The shape of the cross-sectional area is determined from observations under a 
microscope. This shape is usually fixed for all needles of a given species and 
so has to be determined only once for a given species. This shape determines the 
coefficients in an equation that relates the previous measurements to the 
surface area. The shape factor for black spruce is 4.00 (BOREAS Experiment Plan, 
Version 3.0, Appendix K). Based on observations of two cross-sections of two 
needles per fascicle for five fascicles for six jack pine trees from Thompson, 
Manitoba, an average shape factor of 1993 needles was calculated as 4.59 (+0.07)

(1) 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 needles)
n = total number of needles

6. Observations

6.1 Data Notes

None.

6.2 Field Notes

None.

7. Data Description

7.1 Spatial Characteristics

7.1.1 Spatial Coverage

The data were collected from six principal sites in the NSA located in Manitoba.  
The NSA is approximately 100 km by 80 km, and is located 735 km north of 
Winnipeg. The coordinates for each of the principal sites in this study were:

NSA-YA auxilliary site along Gillam Road (auxilliary site number W0Y5A, BOREAS 
Experiment Plan, Version 3.0):
Lat/Long: 56.00339 N, 97.3355 W
UTM Zone 14, N: 6207706.6, E: 603796.6

NSA-YJP flux tower site:
Lat/Long:55.89575 N, -98.28706 W. 
UTM Zone 14, N: 6194706.9 E: 544583.9; 

-Old jack pine (NSA-OJP) flux tower site
Lat/Long: 55.842 N, 98.62396 W
UTM Zone 14, N: 6198176.3, E: 523496.2 

NSA-OA canopy access tower site (auxilliary site number 
T2Q6A, BOREAS Experiment Plan, Version 3.0):
Lat/Long 55.88691 N, 98.67479 W
UTM Zone 14, N: 6193540.7, E: 520342;

NSA-OBS Flux tower site:
Lat/Long: 55.88007 N, 98.48139 W,
UTM Zone 14, N: 6192853.4, E: 532444.5

NSA-UBS canopy access tower site (auxilliary 
site number T6R5S, BOREAS Experiment Plan, Version 3.0):
Lat/Long: 55.90802 N, 98.51865 W
UTM Zone 14, N: 6195947, E: 530092

Quantum sensors (on poles) were used on the canopy access towers in the bottom, 
middle, and top canopy. In the case of the YJP site, where a canopy access tower 
did not exist, sensors were located within 1 km of the flux tower.

7.1.2 Spatial Coverage Map

None.

7.1.3 Spatial Resolution

These data are point source measurements at the indicated sites.

7.1.4 Projection

Not applicable.

7.1.5 Grid Description

Not applicable.

7.2 Temporal Characteristics

7.2.1 Temporal Coverage

Data acquisition at all six sites was repeated for each of the Intensive Field 
Campaigns in 1994. The overall period extended from 24-May-1994 to 17-Sep-1994.

7.2.2 Temporal Coverage Map

During the first IFC, the following sites were measured:
YJP,  29-May;
OJP,  31-May;
YASP, 14-Jun;
OASP, 12-Jun;
OBS,  12-Jun;
TE-BS, 03-Jun.

During the second IFC, the following sites were measured:
YJP,  24-Jul;
OJP,  19,20-Jul;
YASP, 26,30-Jul;
OASP, 21,24-Jul;
OBS,  25-Jul;
TE-BS, 22,23-Jul.

During the third IFC, the following sites were measured:
YJP,  8,11,12-Sep;
OJP,  5,6-Sep;
YASP, 8,11-Sep;
OASP, 2,5,6-Sep;
OBS,  13-Sep;
TE-BS, 12-Sep.

7.2.3 Temporal Resolution

These data were collected during diffuse light conditions (overcast/cloudy days) 
during the three field campaigns between 27-May-1994 and 17-Sep-1994.  Quantum 
sensors were suspended for a minimum period of 2 minutes at each level just 
above a branch level that was subsequently harvested (input readings = 5 
seconds, output readings = 1 minute).  All quantum sensors were connected to the 
same CR10 for simultaneous measurements.

7.3 Data Characteristics

Data characteristics are defined in the companion data definition file 
(te09pnd.def).

7.4 Sample Data Record

Sample data format shown in the companion data definition file (te09pnd.def).

8. Data Organization

8.1 Data Granularity

All of the PAR and Leaf nitrogen Data for NSA Species Data is contained in one 
dataset.

8.2 Data Format(s)

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 files (te09pnd.def).

9. Data Manipulations

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 the canopy was 230, then FPAR under the canopy = 74.16% = ((890-
230)/890) x 100

9.1.1 Derivation Techniques and Algorithms

None.

9.2 Data Processing Sequence

9.2.1 Processing Steps

Data from quantum sensors were 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 Campbell Scientific 
manual for programming information.

The CR10 was programmed to take the data each minute which were being retrieved 
every second, and do the following:

1.  Identify the site location.

2.  Output the Julian day, hour, and minute.

3.  Output the minimum battery voltage. This was done to check for data errors 
caused by a low battery source (if the battery charge is below 9.6 errors can be 
expected in the data set).

4. Output the maximum internal temperature of the module panel. This was done to 
be able to check for data errors if the temperature of the CR10 system was too 
high. Errors can be expected in the data set when the temperature is greater 
than 508C.

5. Output the average, standard deviation, and maximum and minimum radiation 
values for each of the two quantum sensors.

Data were then transferred from the field site to a storage module that was 
brought back to a computer for data transfer and verification.

All raw data were printed. Column headings were inserted and 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 staff to identify when 
the relevant light data were not being taken. This code was normally 1.2 and has 
no other meaning other than to signify that the light values at that time are 
not useful. For example, the sensor may at that 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 were 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 calendar date (cdate) were 
inserted as columns. 

Manitoba time data were converted from a numeric format to a time format 
(because original data were in numeric format). The following command was used 
in Excel, Version 5.0 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 were found. Manitoba time 
was then converted to Greenwich Mean Time (GMT) = Thompson, Manitoba time + 6 
hours.

Shoot silhouette data, SLA 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 were then compared with the original data sheets.

Note that the SLA samples corresponding to the YJP stand in IFC 1 (29-May-1994) 
were misplaced, ground, or lost.  In order to compensate for these lost SLA 
data, the SLA data from the photosynthesis data (27-May, group TE-9B) were 
substituted. The SLA data represent the same sampling levels, but only four 
repetitions were available for this set. Photosynthesis was measured on three 
branches at each canopy level for five YJP trees. An average SLA (based on three 
branches for each canopy level) was used.

Data were recorded automatically by a computer and also printed on a printer. 
Subsequent calculations of different parameters were performed using MS Excel 
for Windows 5.0.

BORIS Staff processed the data by:

1) Reviewing the initial data files and loading them online for BOREAS team 
access.
2) Designing relational data base tables to inventory and store the data.
3) Loading the data into the relational data base tables.
4) Working with the Hyrdology (HYD)-06 team to document the data set.
5) Extracting the standardized data into logical files.

9.2.2 Processing Changes

See Section  9.2.1.

9.3 Calculations

See Section 9.1.

9.3.1 Special Corrections/Adjustments

None.

9.3.2 Calculated Variables

See Section 9.1.?.

9.4 Graphs and Plots

None.

10. Errors

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. There was no evidence of these 
activities during the field season.

If the battery charge is below 9.6 volts, errors can be expected in the data 
set. Although this was checked for in the data set, it is unlikely that a low 
battery charge ever occurred because at every data transfer in the field this 
value was checked.

Errors also can be expected in the data set when the CR10 module temperature 
exceeds 508C. This was checked for in the data set but, despite the warm and dry 
conditionsduring the summer of 1994, it is unlikely that the CR10 evergot too 
warm becasue it was placed in a shady understory location.

10.2 Quality Assessment

10.2.1 Data Validation by Source

All anticipated errors were checked and removed.

10.2.2 Confidence Level/Accuracy Judgment

The TE-09 team is confident that the values are correct.

10.2.3 Measurement Error for Parameters

Not available.

10.2.4 Additional Quality Assessments

None.

10.2.5 Data Verification by Data Center

Data was examined for general consistency and clarity.

11. Notes

Note that the SLA samples corresponding to the YJP stand in IFC 1 (29-May-1994) 
were misplaced, ground, or lost.  In order to compensate for these lost SLA 
data, the SLA data from the photosynthesis data (27-May, group TE-9B) were 
substituted. These SLA data represent the same sampling levels, but only four 
repetitions were available for this set. Photosynthesis was measured on three 
branches at each canopy level for five YJP trees. An average SLA (based on three 
branches for each canopy level) was used.

11.1 Limitations of the Data

None given.

11.2 Known Problems with the Data

Not available.

11.3 Usage Guidance

Not available.

11.4 Other Relevant Information

None.

12. Application of the Data Set

These data are useful for modeling Photosynthesis at different levels in the 
canopy.

13. Future Modifications and Plans

None given.

14. Software

14.1 Software Description

Microsoft Excel 5.0

14.2 Software Access

Contact Microsoft.

15. Data Access

15.1 Contact Information

Ms. Beth Nelson 
BOREAS Data Manager
NASA GSFC
Greenbelt, MD
(301) 286-4005
(301) 286-0239 (fax)
beth@ltpmail.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.  If the data are taken from BORIS, permission must be granted from either 
Marie Coyea or Hank Margolis before the data may be used.

15.4 Data Center Status/Plans

The TE-09 PAR and nitrogen 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 at 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

Tabular ASCII files.

17. References

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 monochrome system, root and leaf analysis, 
operator's manual. Pullman, WA.

LI-COR, Inc. 1991. LI-COR Radiation sensors instruction manual. Publication No. 
8609-56.  Lincoln, NE.

17.2 Journal Articles and Study Reports

Bremner, J.M. and C.S. Mulvaney, 1982. Nitrogen-total. pp. 595-624. In: Page, 
A.L., R. H. Miller and D.R. Keeney (eds.). Methods of Soil Analysis  Part 2. 
Chemical and microbiological properties (2e ed.). Agron. No. 9. ASA-SSSA, 
Madison, WI.

Dang, Q.L., H. Margolis, M.R. Coyea, M. Sy, G.J. Collatz, and C. Walthall. 1996. 
Profiles of PAR, nitrogen, and photosynthetic capacity in the boreal forest: 
implications for scaling from leaf to canopy.  J. Geophys. Res., BOREAS Special 
Issue. In press.

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., 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. Crill, 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.and F. Hall. 1997. BOREAS Overview Paper. JGR Special Issue (in 
press).

17.3 Archive/DBMS Usage Documentation

None.

18. Glossary of Terms

None.

19. List of Acronyms

BOREAS  - BOReal Ecosystem-Atmosphere Study
BORIS   - BOREAS Information System
CGR     - Certified by Group
CPI     - Checked by Principal Investigator
DAAC    - Distributed Active Archive Center
EOS     - Earth Observing System
EOSDIS  - EOS Data and Information System
FPAR    - Fraction of Absorbed Photosynthetically Active Radiation
GMT     - Greenwich Mean Time
GSFC    - Goddard Space Flight Center
HASL    - Half the Area of the Surface of the Leaf
HYD     - Hydrology
IFC     - Intensive Field Campaign
N       - nitrogen
NASA    - National Aeronautics and Space Administration
Net PS  - Net Photosynthetic
NIST    - National Institute of Standards and Technology
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
PRE     - Preliminary
Ps      - Photosynthesis
SLA     - Specific Leaf Area
SSA     - Southern Study Area
TE      - Terrestrial Ecology
UBS     - Upland Black Spruce
URL     - Uniform Resource Locator
YA      - Young Aspen
YJP     - Young Jack Pine

20. Document Information

20.1 Document Revision Dates

     Written:       26-Aug-1996
     Last Updated:  19-Mar-1998

20.2 Document Review Dates
     BORIS Review:    21-Apr-1997
     Science Review:  05-Nov-1997

20.3 Document ID

20.4 Citation

Please contact Hank Margolis or Marie Coyea.

20.5 Document Curator

20.6 Document URL

Keywords
--------------
Canopy profile
Nitrogen profile
PAR profile
PAR-nitrogen relation
Nitrogen allocation
Photosynthesis
FPAR
PAR

TE09_PAR_NITROGEN.doc
04/17/98