BOREAS TGB-05 CO2, CH4, and CO Chamber Flux Data over the NSA

Summary

The BOREAS TGB-05 team collected a variety of trace gas concentration and flux 
measurements at several NSA sites.  This data set contains carbon dioxide (CO2), 
methane (CH4), and carbon monoxide (CO) chamber flux measurements conducted in 
1994 at upland forest sites that experienced stand-replacement fires.  These 
measurements were acquired to understand the impact of fires on soil 
biogeochemistry and related changes in trace gas exchange in boreal forest 
soils.  Relevant ancillary data, including data concerning the soil temperature, 
solar irradiance, and information from nearby unburned control sites, are 
included to provide a basis for modeling the regional impacts of fire and 
climate changes on trace gas biogeochemistry.  The data are provided 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 TGB-05 CO2, CH4, and CO Chamber Flux Data over the NSA

1.2 Data Set Introduction

These measurements are required to understand the impact of fires on soil 
biogeochemistry and related changes in trace gas exchange in boreal forest 
soils.  Relevant ancillary data, including data concerning the soil temperature 
and solar irradiance, are included to provide a basis for modeling the regional 
impacts of fire and climate changes on trace gas biogeochemistry.

1.3 Objective/Purpose

The objective of this study is to examine the effects of fire on soil-atmosphere 
fluxes of trace carbon gases (CO2, CH4, CO) in upland black spruce and jack pine 
ecosystems located within the BOReal Ecosystem-Atmosphere Study (BOREAS) 
Northern Study Area (NSA) near Thompson, Manitoba.

1.4 Summary of Parameters

This data set contains measurements of ambient carbon dioxide (CO2), methane CH4 
and CO  concentrations; CO2, CH4, and CO fluxes; ambient and soil temperatures; 
and solar irradiance. 

1.5 Discussion

The soil-atmosphere exchange of CO2 is an important component of the carbon 
budget of the boreal forest biome.  Soil-atmosphere exchange of CH4 and CO in 
the boreal biome has major effects on the atmospheric content of these 
radiatively and chemically important trace gases.  Closed chamber techniques 
with gas chromatography were used to determine the soil surface flux of CO2, 
CH4, and CO at five BOREAS auxiliary sites in the NSA that were exposed to 
intense stand-replacement fires during the 7-year period prior to 1994. Flux 
data were also obtained at nearby control sites.  Relevant ancillary data were 
simultaneously obtained at the sites.  The experiments were conducted from the 
beginning of June through the end of August 1995. 

The results from this study indicate that upland soils in burned boreal forests 
are generally net sources of both CO2 and CO, but net sinks of atmospheric CH4.   
Soil temperatures in these burned sites were generally higher than those 
observed in nearby unburned controls.  Soil respiration includes both root 
respiration and decomposition of soil organic matter (SOM). Despite the loss of 
root respiration in the burn sites, soil respiration was nearly the same in the 
burn sites as in unburned controls.  This indicates that enhancement of SOM 
decomposition by the warming of the soil offset the reduction in root 
respiration.  In sites exposed to the most intense fires, however, where surface 
organic matter was considerably reduced and converted to charcoal by fire, soil 
respiration was significantly reduced compared to other sites that were 
investigated.  CH4 sinks were generally greater in the well-drained jack pine 
stands than in black spruce stands.  CO fluxes are affected by thermal and 
photochemical production at the soil surface and by microbial consumption deeper 
in the soil.  Thus, CO fluxes in the open burn sites were positive during 
daylight, whereas the fluxes were negative in the unburned forest soils.

1.6 Related Data Sets

BOREAS TGB-01 Soil CH4 and CO2 Profile Data over NSA Tower Sites
BOREAS TGB-01 CH4 and CO2 Chamber Flux Data from NSA Tower Sites
BOREAS TGB-01 CH4 Concentration and Flux Data from NSA Tower Sites
BOREAS TGB-01 SF6 Chamber Flux Data over NSA Jack Pine Sites
BOREAS TGB-03 CO2 and CH4 Chamber Flux Data over the NSA

2. Investigator(s)

2.1 Investigator(s) Name and Title

Dr. Richard G. Zepp and Dr. Roger A. Burke
U.S. EPA, Athens, GA

2.2 Title of Investigation

Trace Gas Exchange in the Boreal Forest Biome:  Effects of Fire and Beaver 
Activity

2.3 Contact Information

Contact 1
---------
Dr. Richard G. Zepp
U.S. Environmental Protection Agency
Athens, GA  
(706) 355-8117
zepp.richard@epamail.epa.gov

Contact 2
---------
Sara Golightley
Raytheon STX Corporation
NASA Goddard Space Flight Center
Greenbelt, MD  
(301) 286-2624
Sara.Golightly@gsfc.nasa.gov

3. Theory of Measurements

The CO2, CH4, and CO fluxes at the surface of the soil are important components 
of the carbon budget of the boreal forest.  Stand-replacement fires may affect 
the soil-surface fluxes of these gases.  Fire removes the canopy and part of the 
moss, lichen, and shrub cover, thus altering soil temperature, moisture, and 
nutrient composition.  Models of trace gas biogeochemistry in the boreal forest, 
such as CENTURY, require field measurements of these fluxes in order to 
calibrate the models and test their predicted fluxes. In order to understand and 
quantify the carbon gas exchange in these systems, it is necessary to measure 
their exchange under a variety of conditions in unburned plots and burned plots 
of various postburn ages.

In particular, CO exchange from the forest ecosystem floor is a poorly 
understood process that may exhibit a significant effect on the ambient CO 
levels.  The forest floor may act as both a source and sink for CO.  Sink 
activity is believed to be the result of consumption of CO by microbial 
activity, while production is primarily the result of thermal and photochemical 
decomposition of living and dead organic matter.  The net exchange from the 
forest floor will therefore be determined by the relative source and sink 
strengths of these processes.  Some parameters that are believed to be important 
in CO exchange are temperature, moisture content, soil nutrient levels, SOM 
content, and light intensity.

4. Equipment

4.1 Sensor/Instrument Description

CH4 and CO2 were measured using a Karl Gas Chromatograph (GC) equipped with 
flame-ionization detector (FID) (for CH4) and thermal conductivity detector 
(TCD) (for CO2).  CO was measured using a Trace Analytical (Menlo Park, CA) RGA-
3 GC.  This instrument isolates CO, and reacts with HgO, producing Hg vapor. The 
Hg vapor is detected by atomic absorbance.  Samples are injected through an 
injection loop (0.5 or 1mL).

Aluminum chamber bases (0.215-m inner diameter [i.d.]) were used for isolating a 
section of the forest floor.  The chambers were anchored with three or four 
spikes that were 0.20 m in length.  The chambers were also equipped with a 
cylindrical skirt to prevent lateral diffusion of gases.  Three skirt sizes were 
used depending on the ecosystem type: 5 cm, 10 cm, and 20 cm.  The opening of 
the base had a trough filled with water to provide support and seal the chamber 
top.

Light measurements were made with an International Light IL1700 radiometer using 
probes for various light regions (SED 623 for visible, SED 240 for ultraviolet 
[UV]-A, and SED 033 for UV-B).

Soil temperature was measured with a portable temperature probe (Cole-Palmer 
thermistor thermometer L-08110-20).

Soil water content was measured using a 1502B Time Domain Reflectometer (TDR) 
[Topp et al., 1980].

4.1.1 Collection Environment

Measurements were made at open sites that had experienced stand-replacement 
fires within the prior 7 years or at nearby shaded control forest sites that had 
not burned for at least 70 years.  The soil temperatures and solar irradiance 
were typically much higher at the burned sites than at the control sites. Data 
were collected under a variety of ambient temperatures ranging from near 0 
degrees C to near 28 degrees C.

4.1.2 Source/Platform

All measurements were made on the ground

4.1.3 Source/Platform Mission Objectives

The mission objective was to measure soil surface CO2, CH4, and CO fluxes and 
relevant ancillary data in fire scars and nearby controls.

4.1.4 Key Variables

CO2, CH4, and CO flux; soil temperature; soil moisture content; and light 
intensity (total, UV-A, and UV-B).

4.1.5 Principles of Operation

The chamber assays for CO, CO2, and CH4 followed the methods established by 
Hutchinson and Livingston [1993]. Analysis of CH4 [Crill, 1991] was conducted 
with 0.5% precision.

4.1.6 Sensor/Instrument Measurement Geometry

Not applicable.

4.1.7 Manufacturer of Sensor/Instrument

RGA-3 Chromatograph
Trace Analytical
3517-A Edison Way  
Menlo Park, CA 94025

IL-1700 Radiometer
International Light, Inc.
17 Graf Road                   
Newburyport, MA 01950

Temperature Probe
Cole-Palmer Instrument Company
7425 North Oak Park Avenue     
Niles, IL 60714 

TDR
Tektronix, Inc.
Beaverton, OR

4.2 Calibration

4.2.1 Specifications

Instruments were configured and maintained according to manufacturers' 
specifications noted in the instruction manuals and were calibrated routinely 
according to standards.  

4.2.1.1 Tolerance

The precision of fluxes, for the trace gas measurements, computed from three 
replicates, is expected to be 15% for CO2 and CH4, and 5-10% for CO.  The 
precision is judged by the standard deviation of the three measurements.

4.2.2 Frequency of Calibration

Calibration was performed immediately before measuring each day's samples.  
Correlation coefficients of 0.99 or better were achieved in all cases.  A 
secondary standard of near atmospheric CO2, CH4, or CO concentration was 
injected periodically during analysis to ensure that no instrumental drift 
occurred.

4.2.3 Other Calibration Information

CH4 and CO2 concentrations were calculated by comparing sample peak areas 
obtained with a Shimadzu CR501 dual channel integrator to those resulting from 
repeated analysis of two CH4 standards and two CO2  standards.  The CH4 
standards contained 0.90-ppm and 2.05-ppm CH4, and the CO2 standards contained 
356.1-ppm and 397.4-ppm CO2.  The standard gases were supplied by the BOREAS 
project and calibrated by the Atmospheric Environment Service (AES) of Canada. 
Based on 10 to 15 daily measurements of these standards, the precision of 
analysis (standard deviation divided by the mean value expressed in percentage) 
was 0.7  0.3% for CH4 and 1.7  0.4% for CO2.  For CO calibration, a standard 
curve was generated each day by injecting calibrated volumes of a 9.5  0.14-ppm 
CO primary standard (National Institute of Standards and Technology, 
Gaithersburg, MD).
 
5. Data Acquisition Methods

A static chamber technique [such as that described by Whalen and Reeburgh, 1988] 
was used to estimate soil/atmosphere CH4 and CO2 exchange.  The chamber consists 
of a permanently deployed circular aluminum collar, with a water seal and skirt, 
and an opaque lid.  The collars were ~10, 25, or 30 cm deep in areas with 
significant moss, lichen, or burned vegetation cover, and ~5 cm deep in areas in 
which the vegetation had burned to the mineral layer.  The lid is constructed of 
aluminum and is equipped with a septum for syringe sampling and a small hole to 
equalize pressure.  The total enclosed area is 0.036 m2, and the enclosed volume 
is about 8.7 liters.  

CH4 and CO2 flux samples were collected at 5-minute intervals over the course of 
20 minutes in 60-mL polypropylene syringes with siliconized polypropylene 
plungers and nylon three-way stopcocks. Syringes were stored in the dark at 
ambient temperature until analysis.  Concentration determinations were made 
using a Carle AGC GC equipped with a TCD and a FID.  Gas samples were introduced 
to the GC via a 10-port gas sampling valve plumbed for the simultaneous filling 
of two sample loops and then injection into two columns.  Separation of CH4 and 
CO2 was accomplished with 1/8-inch outer diameter (o.d.) stainless steel 
Hayesep-D (3 m for the FID side and 2 m for the TCD side) analytical columns. 

Soil-atmosphere CO exchange was measured using transparent, static soil 
chambers.  These chambers consisted of two parts: a semipermanent base installed 
into the ground and a removable glass cover that isolated the atmosphere 
immediately above the base.  The aluminum chamber bases consisted of an open-
ended, 0.215-m i.d. cylinder (the skirt).  The bottom edge of the skirt was 
beveled to aid insertion into the soil.  Skirt lengths were either 0.5 or 0.10 
m, depending upon the thickness of the organic layer above the mineral soil.  A 
concentric trough (~30 cm i.d. and 4 cm deep) was welded to the top of the 
chamber. This trough, when filled with water, provided an airtight seal with the 
top.  Three or four 0.5-cm-o.d. x 10-cm-long aluminum spikes were attached 
symmetrically around the circumference of the skirt to provide a secure 
installation. The glass chamber tops were Kimax (Kimble, Vineland, NJ) 
borosilicate jars (25 cm deep, ~24 cm i.d., volume ~12 liters).  These jars were 
transparent to visible (400-700 nm) and UV-A (315-400 nm) light, but filtered 
out a part of UV-B (280-315 nm) radiation.  Two 1/4-inch holes were drilled in 
the side of each glass jar with a 90-degree radial displacement and ~15 cm 
vertical displacement between each hole.  These holes were used as sampling and 
vent ports.  The holes were plugged with small corks, and needles were inserted 
through the corks.  The vent consisted of a 1inch-long, 22-gauge needle, and the 
sampling port consisted of a 4- to 6-inch-long, 18-gauge needle. Both needles 
were left open to the atmosphere during sampling, thereby preventing pressure 
differentials during experiments.

Soil-atmosphere CO exchange was measured in the following manner.  First, the 
trough of the chamber base was filled with enough water to ensure an airtight 
seal with the chamber top.  Then, the top was quickly but gently placed in the 
trough and a gas sample of ~20 mL was removed from the chamber.  Additional 
samples were collected (usually at 7-minute intervals) for a total of at least 
four samples.  For each sample, the syringe was connected to the sampling needle 
and pumped three times to ensure a well-mixed chamber. Approximately 20 mL of 
sample was collected, and the syringe stopcock was closed.  The back of the 
syringe barrel was sealed with a minimum amount of distilled water and stored in 
a plastic ziplock bag on ice until analysis.  The all-glass syringes (Popper & 
Sons, New Hyde Park, NY) were fitted with gas-tight Teflon stopcocks (Alltech 
Associates, Deerfield, IL) and encased in black heat-shrink tubing to keep their 
contents dark.  Sampling was conducted between the hours of 1000 and 1500 local 
time with the exception of two diurnal studies.

Air and soil temperatures (at a depth of 10 cm for CO2 and CH4; 1.0 cm for CO) 
were measured with a thermocouple probe.  Volumetric soil moisture content was 
measured with a TDR as described by Topp et al. [1984].  Total solar irradiance 
was measured during the CO flux measurements with the light probe placed close 
to the environmental chamber.

6. Observations

6.1 Data Notes

None given.

6.2 Field Notes

Date       Location                     Activity

July 19                                 Arrive Thompson
July 20    Lab                          Set up laboratory
July 21    Gillam Road: 94GR, CGR       CH4, CO2, CO fluxes
July 22    Gillam Road: 92GR, 87GR      CH4, CO2, CO fluxes
July 23    Leaf Rapids Road: 89JP, CJP  CH4, CO2, CO fluxes
July 24    Leaf Rapids Road: 89FR, CFR  CH4, CO2, CO fluxes
July 25    Gillam Road: 94GR            CH4, CO2, CO fluxes; process studies
July 26    Gillam Road: 94GR, 87GR      CH4, CO2, CO fluxes
July 27    Gillam Road: CGR, 92GR       CH4, CO2, CO fluxes
July 28    Gillam Road: CGR, 92GR       CH4, CO2, CO fluxes; process studies
July 29    Tower Beaver Pond            CO flux from pond
July 30                                 Off
July 31                                 Off
Aug 1      Gillam Road: 94GR, 92GR      CH4, CO2, CO fluxes
Aug 2      Gillam Road: CGR, 87GR       CH4, CO2, CO fluxes
Aug 3      Leaf Rapids Rd: 89JP, CJP    CH4, CO2, CO fluxes
Aug 4      Gillam Road: 92GR            CH4, CO2, CO fluxes; diurnal
Aug 5      Gillam Road: 92GR            CH4, CO2, CO fluxes; diurnal continued
Aug 6      Gillam Road: CGR, 87GR       CH4, CO2, CO fluxes
Aug 7      Gillam Road: 94GR, 92GR      CH4, CO2, CO fluxes
Aug 8      Lab                          Shut down equipment; ship soil samples
Aug 14     Arrive Thompson
Aug 15     Lab                          Set up lab
Aug 16     Gillam Road: CGR, 94GR       CH4, CO2, CO fluxes
           94GR #6 dug up by animal;.   re-install in another location about 10 
ft toward Thompson

Aug 17     Gillam Road: 92GR, 87GR      CH4, CO2, CO fluxes
Aug 18     Gillam Road: CGR             CH4, CO2, CO fluxes; diurnal
Aug 19     Gillam Road: CGR             CH4, CO2, CO fluxes; diurnal continued
Aug 20                                  Off
Aug 21     Leaf Rapids Road: 89FR, CFR  CH4, CO2, CO fluxes
Aug 22     Leaf Rapids Road: 89JP, CJP  CH4, CO2, CO fluxes
Four chamber bases missing from 89 Jack Pine site - presumed stolen; remove 
remaining bases to prevent additional theft and remove some chambers from CJP 
site for placement in new control site on Gillam Road

Aug 23     Gillam Road: CGR, 92GR       CH4, CO2, CO fluxes
Aug 24     Gillam Road: 87GR, 94GR      CH4, CO2, CO fluxes
Aug 25     Gillam Road: NGRC, CGR, 87GR CH4, CO2, CO fluxes; SF6 at 87GR
Place three chamber bases in New Gillam Road Control (two medium skirt, one deep 
skirt)

Aug 26     Gillam Road: CGR, 92GR, 87GR  Simul. rain event at CGR, 92GR, 87GR,
	     94GR, NCGR                    94GR; CH4, CO2, CO fluxes at NCGR
Aug 27                                   Off
Aug 28     Gillam Road: CGR, 92GR        CH4, CO2, CO fluxes
Aug 29     Gillam Road: 87GR, 94GR       CH4, CO2, CO fluxes
Aug 30     Gillam Road: 92GR, 94GR, 87GR SF6 diffusion studies
Aug 31     Lab; Leaf Rapids Road: 89FR, CFR  SF6 analysis; SF6 diffusion and 
CH4/CO2 at 89FR and CFR
Sept 1     Gillam Road: 92GR, 94GR       SF6 diffusion studies
Sept 2     Lab                           Pack and ship equipment
Sept 2                                   Leave Thompson

7. Data Description

7.1 Spatial Characteristics

7.1.1 Spatial Coverage

Measurements were performed on upland black spruce (Picea mariana) and jack pine 
(Pinus banksiana) forest sites in the vicinity of the BOREAS NSA, which is 
located near Thompson, Manitoba (5591' N, 9842' W). Four black spruce sites, 
three burned and one control, were selected about 100 km northeast of Thompson, 
Manitoba.  The sites were located at 5609' N, 9644' W; 5608' N, 9642' W.  
All four black spruce sites, which were located within 5 km of each other, were 
exposed to very similar climatic conditions. The jack pine burn site was located 
in a large burn site (115,643 ha; summer 1989) on Hwy 391 near Leaf Rapids, 
Manitoba, 140 km west-northwest of Thompson, Manitoba.  A jack pine stand 
located 133 km west-northwest of Thompson, unburned for at least 80 years, 
served as the control for the jack pine burn site. 

At each site, the environmental chambers were used to measure fluxes within an 
area that was approximately 10,000 m2.  

7.1.2 Spatial Coverage Map

A map showing site locations is included.

7.1.3 Spatial Resolution

The environmental chambers used to measure soil fluxes of CO2, CO, and CH4 
covered an area about 0.036 m2.  Flux measurements for CO2, CO, and CH4 were at 
six locations within the site. 

7.1.4 Projection

Not applicable.

7.1.5 Grid Description

Not applicable.

7.2 Temporal Characteristics

7.2.1 Temporal Coverage

The environmental chambers were used to measure soil surface fluxes between June 
and September 1994.   Data were obtained during Intensive Field Campaign (IFC)-
1, IFC-2, August 1994, and the first week of IFC-3.

7.2.2 Temporal Coverage Map

Not available.

7.2.3 Temporal Resolution

Individual flux measurements generally were made over a period of 20 to 30 
minutes. Flux experiments were routinely conducted between the hours of 10:00 
and 1600. local time with selected diurnal studies during August 1994 conducted 
throughout the day and night. 

The flux and ancillary data at a given black spruce site were obtained with a 
sampling frequency of 2-3 days during the periods noted in Section 7.2.1.  Data 
at the jack pine sites were obtained on a weekly basis.

7.3 Data Characteristics

Data characteristics are defined in the companion data definition file 
(tgb5cflx.def).

7.4 Sample Data Record

Sample data format shown in the companion data definition file (tgb5cflx.def).

8. Data Organization

8.1 Data Granularity

All of the CO2, CH4 and CO Chamber Flux Data over the NSA are 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 file (tgb5cflx.def).

9. Data Manipulations

9.1 Formulae

9.1.1 Derivation Techniques and Algorithms

None. 

9.2 Data Processing Sequence

9.2.1 Processing Steps

Gas samples were collected from the environmental chambers at the field sites, 
transferred to the laboratory, and analyzed by gas chromatography.  The fluxes 
were then calculated from measured concentrations of the gases vs. time.

9.2.2 Processing Changes

None given.

9.3 Calculations

9.3.1 Special Corrections/Adjustments

For each chamber experiment, the concentration of CO within the chamber was 
plotted as a function of time after sealing the chamber top over the base.  
These plots showed three different patterns: (1) linear changes with time, (2) 
first-order decay with time, and (3) initial linear increase followed by a 
diminished rate of increase, often yielding a steady state.  Concentration vs. 
time plots were initially plotted to determine the curve shape, and the data 
analysis was determined based on curve shape.  Data were analyzed by performing 
linear regression (slope = CO exchange rate), by performing log-linear 
regression (slope = first-order rate constant), or by determining the initial 
slope.

9.3.2 Calculated Variables

Fluxes of CO2 and CH4 were calculated by linear regression of the measured 
concentrations of samples (typically five) collected during each chamber 
deployment. CO fluxes were calculated as described in Section 9.3.1. 

9.4 Graphs and Plots

Data were plotted using Lotus Freelance, Lotus 123, and Quattro Pro.

10. Errors

10.1 Sources of Error

A few flux measurements were rejected because of various problems such as loss 
of one or more time points, contaminated or leaky syringes, GC problems, or 
disturbance of the site during sampling. These problems usually became apparent 
when either: (1) the initial concentration was not close to the ambient 
concentration, or (2) the correlation coefficient of the linear regression was 
not significant at the 90% confidence level (r2 = 0.810 for n = 4; r2 = 0.648 
for n = 5).

10.2 Quality Assessment

Based on the actual performance of the flux measurement system during this 
study, the minimum detectable flux of CH4 is estimated to be about 0.3 mg CH4-C 
m-2 d-1, and the minimum detectable flux of CO2 to be 0.1 g CO2-C m-2 d-1. 

10.2.1 Data Validation by Source

Calibrations and instrumentation ranges were checked, and data were checked for 
values that were not in expected ranges.

10.2.2 Confidence Level/Accuracy Judgment

For all of the CO2 and CH4 data analyzed with regressions, data sets were 
rejected if the correlation coefficient of the linear regression was not 
significant at the 90% confidence level (r2 = 0.810 for n = 4; r2 = 0.648 for n 
= 5).  For CO measurements that exhibited decreasing CO concentrations vs. time, 
the data sets were rejected if the correlation coefficient of the linear 
regression of log concentration vs. time was not significant at the 90% 
confidence level.

10.2.3 Measurement Error for Parameters

Typically, replicate measurements of the same gas sample are within 10% RSD for 
CO2, CH4, and CO.  

10.2.4 Additional Quality Assessments

Multiple comparison procedures were performed with the software package 
SigmaStat (Jandel Scientific, San Rafael, CA) to test for statistically 
significant differences in gas fluxes and volumetric water content among sets of 
samples grouped by site or by date within a given site.   Each data group was 
tested for normality (Kolmogorov-Smirnov test) and equal variance (Levene median 
test) with the SigmaStat package.  For comparisons of data groups with normal 
distributions and equal variances, a One Way Analysis of Variance (ANOVA) was 
performed to test for differences in mean values of the different groups.  If 
significant differences in the means were found, then a Student-Newman-Keuls 
(SNK) All Pairwise Multiple Comparisons Procedure was performed to identify 
specific differences between groups.  For comparisons of data groups in which 
normality and/or equal variance conditions were not met, a Kruskal-Wallis ANOVA 
on ranks was performed.  If the differences in the median values among these 
groups were found to be significant, then specific differences between groups 
were tested for by the Dunns Method of All Pairwise Multiple Comparisons.  Mean 
ranks were calculated from the results of the ranking procedures associated with 
the nonparametric tests and are presented to indicate trends in the various 
parameters.  Probability and significance levels were set to 0.05 in the 
SigmaStat package unless otherwise specified.  Simple and multiple linear 
regression procedures were also performed with the SigmaStat package.  Zar 
[1984] and Glanz and Slinker [1990] give details of the statistical tests 
performed. 

10.2.5 Data Verification by Data Center

Data were examined for general consistency and clarity.

11. Notes

11.1 Limitations of the Data

There are no known limitations.  However, the user should be aware that there 
are few other data sets available on soil trace gas fluxes in sites that have 
been recently burned.  Therefore, there is no way at this point to judge the 
representativeness of this data set. 

11.2 Known Problems with the Data

None.

11.3 Usage Guidance

None given.

11.4 Other Relevant Information

The procedures and data obtained in this study are monitored by several 
mechanisms:

a) Formal methods of comparisons.  Several comparisons have been made under 
field and laboratory conditions that have substantiated that the instruments 
used in this study provide reliable measurements of trace gases.

b) Informal comparisons among investigators.  Comparisons of the data obtained 
in this study at unburned control sites with flux data obtained using 
environmental chambers or towers at other BOREAS NSA sites indicate that these 
fluxes are in the same range as those observed elsewhere in this region.  This 
favorable comparison suggests that these results are representative of this 
region.

c) Review in the scientific literature.  These and other BOREAS results will be 
published in a timely fashion in a Special Issue of the Journal of Geophysical 
Research so that they will be available to the international scientific 
community.  In these publications, the methods must be justified to peer 
referees.  These justifications are based on other published methods and tests, 
which are described in previous papers.

12. Application of the Data Set

None given.

13. Future Modifications and Plans

None.

14. Software

14.1 Software Description

These results are being used to improve the CENTURY soils model so that it can 
be used to evaluate carbon storage and trace gas fluxes in boreal forest soils. 

14.2 Software Access

The SigmaStat, Lotus, and other commercial software packages are available from 
their specific commercial developers.

The CENTURY software will be available from Dr. Dennis Ojima and Dr. William 
Parton, NREL, Colorado State University, Ft. Collins, CO.  The data also likely 
will be used to improve and test other models that simulate the biosphere-
atmosphere exchange of trace gases. 

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.

15.4 Data Center Status/Plans

These 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 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

Burke, R.A., R.G. Zepp, M.A. Tarr, W.L. Miller, and B.J. Stocks. 1998. Effect of 
fire on soil-atmosphere exchange of methane and carbon dioxide in a Canadian 
Boreal Forest. J.Geophys. Res.  (accepted).

Crill, P.M. 1991. Seasonal patterns of methane uptake and carbon dioxide release 
by a temperate woodland soil.  Global Biogeochemical Cycles 5: 319-334.

Glanz, S.A. and B.K. Slinker. 1990. Primer of Applied Regression and Analysis of 
Variance. McGraw-Hill, New York, 777 pp.

Hutchinson, G.L., and G.P. Livingston. 1993.  Use of chamber systems to measure 
trace gas fluxes, in Agricultural Ecosystem Effects on Trace Gases and Global 
Climate Change.  ASA Special Publication No. 55. American Society of Agronomy, 
Madison, WI, pp. 63-78.

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. Versi on 1996-2.0, NASA BOREAS Report (EXPLAN 96). 

Sellers, P.and F. Hall. 1997. BOREAS Overview Paper. JGR Special Issue (in 
press). Whalen, S.C., and W.S. Reeburgh.  1988. A methane flux time series for 
tundra environments. Global Biogeochem. Cycles, 2, 399-409.

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. 

Topp, G.C., J.L. Davis, W.G. Bailey, and W.D. Zebchuk. 1984. The measurement of 
soil water content using a portable TDR hand probe. Can. J. Soil Sci., 313-321.

Zar, J.H. Biostatistical Analysis, 2nd Ed. Prentice-Hall, Englewood Cliffs, NJ, 
718 pp.

Zepp, R.G., W.L. Miller, M.A. Tarr, R.A. Burke, and B.J. Stocks. 1998. Soil-
atmosphere fluxes of carbon  monoxide during early stages of post-fire 
succession in upland Canadian boreal forests. J. Geophys. Res. (accepted).

17.3 Archive/DBMS Usage Documentation

None.

18. Glossary of Terms

None given.

19. List of Acronyms 

    AES     - Atmospheric Environment Services
    ANOVA   - One Way Analysis of Variance
    ASCII   - American Standard Code for Information Interchange
    BOREAS  - BOReal Ecosystem-Atmosphere Study
    BORIS   - BOREAS Information System
    CGR     - Certified by Group
    CPI     - Checked by PI
    CPI-??? - CPI but questionable
    DAAC    - Distributed Active Archive Center
    EOS     - Earth Observing System
    EOSDIS  - EOS Data and Information System
    FID     - Flame Ionization Detector
    GC      - Gas Chromatograph
    GMT     - Greenwich Mean Time
    GSFC    - Goddard Space Flight Center
    IFC     - Intensive Field Campaign
    NASA    - National Aeronautics and Space Administration
    URL     - Uniform Resource Locator
    PANP    - Prince Albert Natinoal Park
    PI      - Principal Investigator
    PRE     - Preliminary
    ORNL    - Oak Ridge National Laboratory
    SNK     - Student-Newman-Keuls
    SOM     - Soil Organic Matter
    SSA     - Southern Study Area
    TCD     - Thermal conductivity Detector
    TDR     - Time Domin Reflectometer
    TGB     - Trace Gas Biogeochemistry
    UV      - Ultraviolet

20. Document Information

20.1 Document Revision Date 

     Written:  04-Jun-1997
     Last updated: 20-Jul-1998

20.2 Document Review Date(s)

     BORIS Review:  06-Oct-1997
     Science Review:  

20.3 Document ID 

20.4 Citation 

20.5 Document Curator 

20.6 Document URL 

Keywords
  
Methane
Carbon Dioxide
Carbon Monoxide


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