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 53.80206°N, 104.61798°W. 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