BOREAS TF-11 Biomass Data over the SSA-Fen

Summary:

The BOREAS TF-11 team collected several data sets in their efforts to fully 
describe the flux and site characteristics at the SSA-Fen site.  This data set 
contains plant cover, standing crop of plant biomass, and estimated net primary 
productivity at each chamber site at the end of the 1994 field season.  The 
measurements were conducted as part of a 2x2 factorial experiment in which we 
added carbon (300 g m-2 as wheat straw) and nitrogen (6 g m-2 as urea) to four 
replicate locations in the vicinity of the TF-11 tower.  The data are stored in 
tabular ASCII files.

Table of Contents    
*  1 Data Set Overview    
*  2 Investigator(s)    
*  3 Theory of Measurements    
*  4 Equipment    
*  5 Data Acquisition Methods    
*  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 TF-11 Biomass Data over the SSA-Fen

1.2 Data Set Introduction

This data set contains standing crop of plant biomass and estimated net primary 
productivity at each chamber site at the end of the 1994 field season.  The 
measurements were conducted as part of a 2x2 factorial experiment in which we 
added carbon (300 g m-2 as wheat straw) and nitrogen (6 g m-2 as urea) to four 
replicate locations in the vicinity of the TF-11 tower.            

1.3 Objective/Purpose     

Much of the area within the boreal forest biome is comprised of wetlands, in 
which large carbon stores and high water tables drive fundamentally different 
atmospheric interactions than occur under the other forest types studied by 
BOREAS. One key difference is in the form carbon is emitted following soil 
microbial respiration-in wetlands, much of it is emitted as methane.  Wetlands 
are the dominant influence of boreal forests on atmospheric methane.         

This study was undertaken in order to assess responses of methane emissions in 
northern wetlands to potential changes in plant productivity, nitrogen 
availability or both.  Whiting and Chanton (1993) recently observed that 
methane emissions from wetlands across the globe are well related to net 
primary productivity.  This may be for a variety of reasons, including enhanced 
plant transport, increased methanogenic substrates from root exudates, 
increased litter input cascading to enhanced substrate availability for 
methanogenesis, or enhanced C and N mineralization of decomposing residues.  
Previous work by others and us (Valentine et al. 1994) has shown that substrate 
availability is a key constraint on methane production in wetlands.  The 
present study was an effort to test whether substrate manipulation results from 
laboratory studies could be mirrored under field conditions.

1.4 Summary of Parameters     

We report the standing crop of live plant biomass, by growth form, clip-
harvested from our flux chambers in mid-September 1994.  Based on these and the 
procedure outlined by Klinger et al. (1994), we also estimated net primary 
productivity by growth form.

1.5 Discussion     

These data were collected from a set of small locations within the fen, and 
therefore no one location represented the entire study site.  In fact, the fen 
in which this work was conducted was characterized by a large scale gradient of 
vegetation, microtopography, and hydrology such that the study site itself is 
only representative of the portion of the fen in which it was located (i.e. the 
lower 1/3).

These data were collected at the same site and over the same time period as 
Shashi Verma and his team measured methane and carbon dioxide fluxes using eddy 
correlation.  Tim Arkebauer collected more detailed data on plant species 
composition and dominance at this site.

1.6 Related Data Sets     

BOREAS TE-06 Biomass Estimate Data
BOREAS TE-18 Biomass Density Image of the SSA
BOREAS TF-11 CO2 and CH4 Concentration data from the SSA-Fen
BOREAS TF-11 CO2 and CH4 Flux data from the SSA-Fen
BOREAS TGB-03 Plant Species Composition Data over the NSA Fen

2. Investigator(s) 

2.1 Investigator(s) 

David Valentine
Research Associate (through 16 Aug 1996)                 
Assistant Professor (since 01 Sep 1996) 

Affiliations:         
Until 16-Aug-1996:      
Natural Resource Ecology Laboratory                                         
Colorado State University                                         
Fort Collins, CO      

Since 01-Sep-1996:      
Department of Forest Sciences                                         
University of Alaska                                         
Fairbanks, AK 

2.2 Title of Investigation

Influence of substrate characteristics and other environmental factors on 
methane emissions from the BOREAS Southern Study Area fen site.  IV. Standing 
crop.

2.3 Contact Information     

Contact 1
---------
David Valentine 
Department of Forest Sciences 
University of Alaska 
Fairbanks, AK 
(907) 474-7614 
(907) 474-6184 (fax) 
ffdwv@aurora.alaska.edu

Contact 2
---------
Sara Conrad
Raytheon STX Corporation
NASA/GSFC
Greenbelt, MD 
(301) 286-2624
(301) 286-0239 (fax)
Sara.Conrad@gsfc.nasa.gov

3. Theory of Measurements    

Above-ground biomass was assessed by clip-harvesting at the end of the growing 
season, separating by taxonomic unit (species where possible), and weighing 
oven dry corrected samples.  Data were aggregated and reported by growth form.

4. Equipment:

4.1 Sensor/Instrument Description     

4.1.1 Collection Environment       

The clip harvest occurred from 13-16 September 1994, as many of the plants had 
begun to senesce.

4.1.2 Source/Platform       

All chamber sites were fitted with stainless steel bases cut into the surface 
10 cm of peat at the beginning of the season.  All bases remained in place 
during the entire summer.  We clipped the vegetation contained in each base to 
obtain end of season above ground plant biomass.

4.1.3 Source/Platform Mission Objectives       

Recent papers (e.g. Whiting and Chanton 1993) have suggested that CH4 emissions 
are positively related to plant productivity.  As we observed substantial 
variability among the chamber bases with respect to aboveground plant biomass, 
we decided to harvest them to examine possible relationships between above 
ground biomass and CH4 emissions.

4.1.4 Key Variables       

COVER - Fraction of area covered by taxon 
BIOMASS - g/m2 -Oven dry weight of growth form's above ground parts
NPP - g/m2/y - Estimated aboveground net primary productivity 

4.1.5 Principles of Operation       

None given.

4.1.6 Sensor/Instrument Measurement Geometry       

None given.

4.1.7 Manufacturer of Sensor/Instrument       

None given.

4.2 Calibration     

4.2.1 Specifications       

4.2.1.1 Tolerance        

None given.

4.2.2 Frequency of Calibration      

None given.

4.2.3 Other Calibration Information       

None given.

5. Data Acquisition Methods    

After monitoring CH4 and CO2 fluxes at a number chamber collars through the 
growing season, we estimated plant cover by eye and harvested all aboveground 
plant biomass at each collar and classified it according to growth form: Moss, 
shrub, graminoid, and herbaceous.  All samples were oven dried at 30 C for 48 h 
before weighing. 

6. Observations    

6.1 Data Notes 

Plant identification to genus and species was not attemted because at the time 
of clipping senescence had obscured many foliar details and flowering had long 
past for most species. 

6.2 Field Notes 

None given.

7. Data Description 

7.1 Spatial Characteristics     

7.1.1 Spatial Coverage       

All measurements were made along two transects identified by their location 
relative to the TF-11 micrometeorology tower:  a north transect (NA and NB 
platforms) and a south transect (SA and SB platforms).  All measurements were 
made within 70 m of the TF-ll tower whose North American Datum of 1983 (NAD83) 
coordinates are 53.80206N, 104.61798W.

7.1.2 Spatial Coverage Map       

Not available.

7.1.3 Spatial Resolution       

These data are point measurements at the given locations.

7.1.4 Projection       

Not applicable

7.1.5 Grid Description       

Not applicable

7.2 Temporal Characteristics     

7.2.1 Temporal Coverage       

Plant cover, biomass, and NPP data are from clip-harvests performed 13-16 
September, 1994, covering accumulated plant biomass for the 1994 growing season 
(for herbaceous and graminoid species) and previous growing seasons (for shrubs 
and bryophytes). 

7.2.2 Temporal Coverage Map       

None.

7.2.3 Temporal Resolution      

One's objective determines when above ground biomass should be collected. Peak 
biomass is collected when biomass is largest, and is useful in relating to peak 
CH4 or CO2 flux rates.  End of season biomass is collected at senescence, and 
is useful for estimating likely litter inputs to the ecosystem.  We were 
constrained by our need to monitor CH4 fluxes at the sites where ultimately 
above ground biomass would also be determined. 

7.3 Data Characteristics                                                        
                                                                                
Data characteristics are defined in the companion data definition file 
(tf11biom.def).

7.4 Sample Data Record                                                          
                                                                                
Sample data format shown in the companion data definition file (tf11biom.def).

8. Data Organization    

8.1 Data Granularity

All of the Biomass Data over the SSA-Fen 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 single apostrophe 
marks. There are no spaces between the fields. Sample data records are shown in 
the companion data definition file (tf11biom.def).

9. Data Manipulations 

9.1 Formulae 

9.1.1 Derivation Techniques and Algorithms     

NPP was estimated as BIOMASS * PBR, where PBR (the productivity/biomass ratio) 
was taken from Klinger et al. (1994) Table 1.  All graminoid and herbaceous 
plants and shrub leaves had a PBR of 1.0 (i.e. all biomass was produced during 
the current growing season).  Shrub stems were given a PBR of 0.21 and 
bryophytes were given a PBR of 0.68. 

9.2 Data Processing Sequence 

9.2.1 Processing Steps       

None given.

9.2.2 Processing Changes       

None given.

9.3 Calculations 

9.3.1 Special Corrections/Adjustments       

None given.

9.3.2 Calculated Variables 

See Section 9.1.1

9.4 Graphs and Plots 

None given.

10. Errors 

10.1 Sources of Error      

The largest source of error for both biomass measurements and NPP calculations 
is the below ground component.  All values reported here are for aboveground 
parts only; the reader should exercise care in extrapolating from these to 
ecosystem biomass and NPP values.  The NPP estimates are calculated based on 
assumed ratios of current production to biomass; although derived for boreal 
ecosystems, their applicability to this site and species composition is 
untested.  Finally, the influence of the permanently installed chamber collars 
and periodically placed chambers is unknown but perhaps important.  Possible 
mechanisms include severance of plant roots and rhizomes by the collar 
placement, greater thermal conductivity of steel into the rooting zone, and 
potential lensing by the chamber film causing damage to foliage during flux 
measurement prior to the clip harvest. 

10.2 Quality Assessment  

10.2.1 Data Validation by Source        

None given.

10.2.2 Confidence Level/Accuracy Judgement        

The above ground plant biomass data are fairly solid as sufficient care was 
exercised during the growing season to cause minimal disturbance and during the 
clip harvest to sample quantitatively.  For the reasons noted in sections 9.1 
and 10.1, care should be taken in interpreting estimated NPP as it was 
calculated rather than measured through sequential harvests. 

10.2.3 Measurement Error for Parameters        

None given.

10.2.4 Additional Quality Assessments        

None given.

10.2.5 Data Verification by Data Center        

Data were examined for general consistency and clarity.

11. Notes 

11.1 Limitations of the Data 

See sections 9.1 and 10.1 

11.2 Known Problems with the Data      

None given.

11.3 Usage Guidance      

See sections 9.1 and 10.1 

11.4 Other Relevant Information      

None given.

12. Application of the Data Set     

Several avenues are being pursued in publications now being produced to answer 
the following questions: 

1.  How do CH4 flux measurements compare by technique used in measurement?           
2.  How and why do CH4 flux measurements vary through time and across the 
    landscape?
3.  Does plant productivity limit CH4 emissions? 

13. Future Modifications and Plans     

None given.

14. Software

14.1 Software Description

We used only commercially available software, mostly the Quattro Pro 
spreadsheet. 

14.2 Software Access 

None given.

15. Data Access     

15.1 Contact Information

Ms. Beth Nelson
BOREAS Data Manager
NASA GSFC
Greenbelt, MD 
(301) 286-4005
(301) 286-0239 (fax)
Elizabeth.Nelson@gsfc.nasa.gov

15.2 Data Center Identification

See Section 15.1.

15.3 Procedures for Obtaining Data

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

15.4 Data Center Status/Plans 

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 

Comma delimited ASCII text files.

17. References 

17.1 Platform/Sensor/Instrument/Data Processing Documentation      

None.

17.2 Journal Articles and Study Reports      

Klinger, L.F., P.R. Zimmerman, J.P. Greenberg, L.E. Heidt, and A.B. Guenther.  
1994.  Carbon trace gas fluxes along a successional gradient in the Hudson Bay 
lowland.  J. Geophys. Res. 99:1469-1494. 

Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment 
Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). 

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., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere 
Study: 1994 Operations. NASA BOREAS Report (OPS DOC 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. 1997. Boreal Ecosystem-Atmosphere 
Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96). 

Sellers, P. J., F. G.  Hall, R. D.  Kelly, A.  Black, D.  Baldocchi, J.  Berry, 
M.  Ryan, K. J.  Ranson, P. M.  Crill, D. P.  Lettenmaier, H.  Margolis, J.  
Cihlar, J. Newcomer, D.  Fitzjarrald, P. G.  Jarvis, S. T.  Gower, D.  
Halliwell, D.  Williams, B.  Goodison, D. E.   Wickland, and F. E. Guertin. 
1997. BOREAS in 1997: Experiment Overview, Scientific Results and Future 
Directions. Journal of Geophysical Research 102 (D24): 28,731-28,770.

Whiting G.J., Chanton J.P. 1993. Primary production control of methane emission 
from wetlands. Nature 364:794-5. 

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     
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 
SSA     - BOREAS Southern Study Area     
NPP     - Net primary productivity 

20. Document Information

20.1 Document Revision Date      

Written:         29-Jan-1997
Last Updated:    06-Oct-1998

20.2 Document Review Date(s)      

BORIS Review:      06-Oct-1998
Science Review: 

20.3 Document ID

20.4 Citation      

Valentine, D.W.  1996.  Influence of substrate characteristics and other 
environmental factors on methane emissions from the BOREAS Southern Study Area 
fen site.  IV.  Above ground plant cover, biomass, and estimated productivity. 

20.5 Document Curator      

20.6 Document URL     

Keywords:
Carbon
biomass
nitrogen
TF11_Biomass.doc
10/09/98