BOREAS TE-06 NPP Estimates for the BOREAS TF, CEV, and AUX Sites Summary The BOREAS TE-06 team collected several data sets to examine the influence of vegetation, climate, and their interactions on the major carbon fluxes for boreal forest species. This data set contains estimates of the biomass produced by the plant species at the TF, CEV, and AUX sites in the SSA and NSA for a given year. Temporally, the data cover the years of 1985 to 1995. The plant biomass production (i.e., aboveground, belowground, understory, litterfall), spatial coverage, and temporal nature of measurements varied between the TF, CEV, and AUX sites as deemed necessary by BOREAS principal investigators. 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 TE-06 NPP Estimates for the BOREAS TF, CEV, and AUX Sites 1.2 Data Set Introduction The data provided are estimates of the accumulation of biomass by the plant species for a given year, or net primary productivity (NPP), at the BOReal Ecosystem-Atmosphere Study (BOREAS) Northern Study Area (NSA) and Southern Study Area (SSA) Tower Flux (TF), Carbon Evaluation (CEV), and Auxiliary (AUX) sites. Estimates for the aboveground and belowground biomass increment and detritus production and the understory biomass increment are found to varying degrees within these data sets for all sites. These NPP data sets are part of the effort by the Terrestrial Ecology (TE)-06 team to develop carbon budgets for the various Canadian boreal forest types. NPP is both the result of, and the precursor to a number of important dynamics within the boreal forest that determine whether this forest type is a sink or source of carbon dioxide in climate change scenarios. 1.3 Objective/Purpose The objective of this study was to quantify the NPP for the TF, CEV, and AUX sites. 1.4 Summary of Parameters Aboveground NPP(ANPP) stem increment, foliage increment, understory increment, litterfall, root NPP, overstory biomass increment. 1.5 Discussion NPP is an estimate of the incremental production of biomass by plants in an ecosystem. Generally, NPP is the sum of overstory biomass increment, aboveground litterfall, and belowground detritus production. The data sets collected are part of the TE-06 team's effort to quantify the plant carbon sequestration as expressed by the production of biomass in a given year. Diameter measurements were made for variable radius and fixed area plots at each site. Stem increment data and allometric equations were then used to quantify biomass for a given year, and the difference between years was considered ANPP. Litterfall was measured at the TF sites and the CEV sites with litter screens. NPP estimates for the TF and CEV sites are of good quality because they were derived from site-specific allometric equations and direct measurements of litterfall. Foliage and litterfall estimates derived for the AUX sites may suffer from not being site specific allometric equations. From a spatial perspective, the TF site plots were located in areas that approximated the ANPP of the forest within the Wind-Aligned Blob (WAB), while the CEV and AUX plots were located to describe the ANPP within a 30 x 30 m area. 1.6 Related Data Sets BOREAS TE-06 Biomass Estimates Data BOREAS TE-06 Allometry Data 2. Investigator(s) 2.1 Investigator(s) Name and Title Tom Gower, Professor University of Wisconsin-Madison 2.2 Title of Investigation Measurement and Scaling of Carbon Budgets for Contrasting Boreal Forest Sites 2.3 Contact Information Contact 1 ---------------- Tom Gower University of Wisconsin-Madison Madison WI (608) 262-0532 stgower@facstaff.wisc.edu Contact 2 ------------- Jason G Vogel University of Wisconsin-Madison Madison WI (608) 262 6369 vogel@calshp.cals.wisc.edu Contact 3 ------------- Shelaine Curd Raytheon STX Corporation NASA/GSFC Greenbelt, MD (301) 286-2447 (301) 286-2039 (fax) Shelaine.Curd@gsfc.nasa.gov 3. Theory of Measurements The accumulation of biomass, or NPP, is the net result of photosynthesis by a plant after plant respiration. These measurements were made to best quantify ANPP for the years 1993 and 1994 for the TF and CEV sites and 1994 and 1995 for the AUX sites. Historical overstory biomass increment estimates are provided, although accuracy becomes an increasing problem where historical data are concerned because of plot sampling methodology and allometric equation limitations. 4. Equipment 4.1 Sensor/Instrument Description 10 Basal Area Factor (BAF) prism, diameter tape, 50-m measuring tape, increment borer, Dual Axis Optical Micrometer (M-2001-D) Series with a Spalding B5 Digital Position Display System (7109-C225) that is used to measure the distance between tree rings, hydropneumatic elutriator system (separates roots from soil). 4.1.1 Collection Environment Measurements were made under a variety of field conditions that had no effect on the quality of measurements. 4.1.2 Source/Platform Not applicable. 4.1.3 Source/Platform Mission Objectives Not applicable. 4.1.4 Key Variables Not applicable. 4.1.5 Principles of Operation The Dual Axis Optical Micrometer and Spalding B5 Digital Position Display System are two components of a system that allow an operator to view a tree's rings through a microscope, measure the distance between two rings, and then download the distance into a spreadsheet. This increment is then used to estimate overstory increment. 4.1.6 Sensor/Instrument Measurement Geometry Not applicable. 4.1.7 Manufacturer of Sensor/Instrument Dual Axis Optical Micrometer and Spalding B5 Digital Position Display System: Gaertner Scientific 1201 Wrightwood Ave. Chicago, IL 60614 (312) 281 5335 Hydropneumatic Elutriator System Gillison's Variety Fabrication, Inc. Benzonia, MI Instrument Specifications found in Smucker et al., 1982 4.2 Calibration 4.2.1 Specifications None given. 4.2.1.1 Tolerance None given. 4.2.2 Frequency of Calibration The micrometer was periodically checked for precision, but calibration was never needed. 4.2.3 Other Calibration Information None given. 5. Data Acquisition Methods Understory and overstory increment, fine root NPP, and litterfall estimates were made for the overstory and understory at the mature Picea mariana, Pinus banksiana, and Populus tremuloides TF sites (Old Black spruce (OBS), Old Jack Pine (OJP), and Old Aspen (OA) respectively). At the CEV sites, the understory and overstory increment and litterfall were measured. Only the overstory increment was measured at the AUX sites. In the field, plots were established using either a 10 BAF prism or a measuring tape. The diameters of trees located within a plot were measured, and either a disk or a core was removed at the exact place a diameter measurement was made. In the lab, the distance between the tree rings was measured to the nearest 0.001 mm. The diameter for successive years was then calculated, and allometric equations were used to determine the biomass for that year. The difference in biomass was considered the overstory ANPP. The other component of ANPP, litterfall, was measured at the TF and CEV sites by placing 40 60 x 40 cm or 5 1 x 1 m screens in the plots. The difference in the number of screens placed at the TF vs CEV sites was a function of the area that we were attempting to describe the litterfall amount for; the 500 m WAB at the TF sites and a 30x30 m area at the CEV sites. For two CEV sites, D9G4A and D9I1M, litterfall was estimated from the new foliage allometric equation developed for D9I1M, and therefore there are only estimates for the aspen foliage. The litter screen size used depended on the tree density; for greater density, smaller screens were used. The screens were collected in the fall and spring to determine 1 year of litterfall. The litterfall was separated by species foliage and the nonfoliage component. Understory vegetation was sampled from a 2 x 2 or 1 x 1 m subplot that was randomly located in each of the plots. The subplot size varied depending on plant density. All vegetation in the plot was clipped and stored in a cold room ( 3 8C) until it was processed. Samples were separated into three categories: ephemeral, new foliage and twig from perennial plants, and old foliage and twig from perennial plants. Samples were dried and weighed to the nearest 0.1 g. Understory NPP was calculated as the sum of the ephemeral, new twig, and new foliage tissues. Stem increment was measured for the shrub layer at the southern OA and the northern CEV aspen (in the same manner as above), but was not measured at other sites because the radial increment was too small. Fine root NPP was also estimated using ingrowth cores. Cores were established on 28-30-Apr-1994, at the jack pine and aspen stands at the SSA and the NSA and on 28-May to 04-Jun-1994 at the Black spruce stands and all the NSA stands. The difference in sampling dates occurred because the soil was still frozen at the SSA black spruce and all stands at the NSA in late April 1994. Ice lenses were encountered in all stands at the time of sampling, suggesting that root growth had not yet begun by April in 1994. Ten cores (10 cm diameter * 30 cm depth) were taken from each plot, and the soil was separated by horizon and composited by plot. The composited soil from each horizon was thoroughly mixed on a tarp and sieved to pass through a 1-cm mesh screen. The sieved soil was thoroughly mixed by hand, and as many fine roots as possible were removed. The root-free soil was placed by horizon into each hole, and forest floor was replaced on top of the hole. It was impossible to sieve the thick organic layer at the black spruce stands; therefore, only the mineral soil was sieved, and the organic layer was replaced with commercially available sphagnum, which had been harvested in southeastern Manitoba. To mimic the hydrologic and chemical characteristics of the surrounding peat, water was collected from nearby free- standing pools and used to saturate each sphagnum core. In June 1995 and 1996, five ingrowth cores per plot were sampled using a 5 cm diameter x 30 cm deep corer. Samples were stored in plastic bags at 3 8C until processed. Cores were washed with the hydropneumatic elutriator system (Gillison's Variety Fabrication, Inc., Benzonia, MI), and all live roots were collected. Roots were sorted and classified as herbaceous or woody. Samples were dried at 70 8C to a constant mass and weighed. Dried root tissue from each plot was composited, ground in a Wiley mill to pass through a 1-mm screen, and dry-ashed in a muffle furnace at 450 8C for 24 hours to determine ash content. Fine root NPP was calculated for each year by dividing fine root mass by the number of years the ingrowth cores were in the ground. Not all measurements were made for all productivity components at all sites. The following is a description of the NPP what, when, and where for the TF, CEV, and AUX sites. TF= 1993 and 1994 overstory increment and litterfall. 1994 understory increment. 1994 and 1995 root/fine root production. CEV=1993 and 1994 overstory increment. 1994 litterfall and understory increment. AUX=1995 and 1994 overstory increment. 6. Observations 6.1 Data Notes None given. 6.2 Field Notes None given. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage At the TF sites, four replicate plots were established immediately outside the footprint of the tower. The plots were located in areas that reasonably represented the vegetation within the WAB and should provide accurate stand level descriptions. The plot size varied from 7.5 x 7.5 m to 30 x 30 m depending upon tree density. The number of trees per plot ranged from 60 to 120. The CEV and AUX sites were sampled to describe the biomass within a 30 x 30 m area. SITE LATITUDE LONGITUDE ------------------------- ---------- ---------- NSA-9BS-9TETR 55.90802 N 98.51865 W NSA-9BS-AUX01 55.76824 N 97.84024 W NSA-9BS-AUX02 55.78239 N 97.80937 W NSA-9BS-AUX03 55.83083 N 97.98339 W NSA-9BS-AUX04 55.83455 N 97.98364 W NSA-9BS-AUX05 55.83913 N 97.99325 W NSA-9BS-AUX06 55.87968 N 98.18658 W NSA-9BS-AUX07 55.88351 N 98.80225 W NSA-9BS-AUX08 55.88371 N 98.82345 W NSA-9BS-AUX09 55.89358 N 98.22621 W NSA-9BS-AUX10 55.9061 N 97.70986 W NSA-9BS-AUX12 55.91021 N 97.70281 W NSA-9BS-AUX13 55.91506 N 98.44877 W NSA-9BS-AUX14 55.9161 N 98.64022 W NSA-9BS-AUX15 55.91689 N 98.37111 W NSA-9JP-AUX01 55.55712 N 98.02473 W NSA-9JP-AUX02 55.88173 N 99.03952 W NSA-9JP-AUX03 55.89486 N 98.30037 W NSA-9JP-AUX04 55.90456 N 98.28385 W NSA-9JP-AUX05 55.90539 N 98.26269 W NSA-9JP-AUX06 55.93219 N 98.6105 W NSA-9JP-AUX07 55.93737 N 98.59568 W NSA-9OA-9TETR 55.88691 N 98.67479 W NSA-ASP-AUX02 55.56227 N 98.02635 W NSA-ASP-AUX04 55.84757 N 98.04329 W NSA-ASP-AUX05 55.88576 N 98.87621 W NSA-ASP-AUX07 55.91856 N 98.37041 W NSA-ASP-AUX08 55.97396 N 97.48565 W NSA-ASP-AUX09 56.00339 N 97.3355 W NSA-MIX-AUX02 55.88911 N 98.85662 W NSA-OBS-FLXTR 55.88007 N 98.48139 W NSA-OJP-FLXTR 55.92842 N 98.62396 W SSA-9BS-AUX01 53.64877 N 105.29534 W SSA-9BS-AUX02 53.90349 N 104.63785 W SSA-9BS-AUX03 53.93021 N 105.13964 W SSA-9BS-AUX04 53.94446 N 104.759 W SSA-9BS-AUX05 53.99877 N 105.11805 W SSA-9BS-AUX07 54.06199 N 105.92545 W SSA-9JP-AUX02 53.86608 N 105.11175 W SSA-9JP-AUX03 53.88211 N 105.03226 W SSA-9JP-AUX04 53.88336 N 105.05115 W SSA-9JP-AUX05 53.9088 N 104.74812 W SSA-9JP-AUX06 53.91883 N 104.76401 W SSA-9JP-AUX07 53.95882 N 104.77148 W SSA-9JP-AUX08 53.96558 N 104.63755 W SSA-9JP-AUX09 53.97576 N 104.73779 W SSA-9JP-AUX10 54.11181 N 105.05107 W SSA-9OA-FLXTR 53.62889 N 106.19779 W SSA-ASP-AUX03 53.66879 N 104.6388 W SSA-ASP-AUX05 53.74019 N 105.46929 W SSA-MIX-9TETR 53.7254 N 105.20643 W SSA-MIX-AUX01 53.80594 N 104.533 W SSA-MIX-AUX02 53.9375 N 105.14246 W SSA-MIX-AUX03 54.06535 N 105.92706 W SSA-MIX-AUX04 54.066 N 105.92982 W SSA-OBS-FLXTR 53.98717 N 105.11779 W SSA-OJP-FLXTR 53.91634 N 104.69203 W 7.1.2 Spatial Coverage Map Not available. 7.1.3 Spatial Resolution The plot sizes varied from 7.5 x 7.5 m to 30 x 30 m depending upon tree density. 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Tower flux sites: Overstory increment and litterfall were measured in 1993 and 1994. Understory increment was measured in 1994. Root/fine root production were measured in 1994 and 1995 Carbon Evaluation Sites Overstory increment was measured in 1993 and 1994. Litterfall and understory increment were measured in 1994. Auxiliary sites Overstory increment was measured in 1994 and 1995. Overstory increment numbers are also provided for 1985-1992 and 1986-1993 at the TF/CEV and AUX sites, respectively; however, the accuracy of these numbers likely decreases as one projects back in time (see Section 10.1). 7.2.2 Temporal Coverage Map Not available. 7.2.3 Temporal Resolution All NPP measurements based on plant dry matter accumulation are expressed on a yearly basis. The number of human hours it takes to make the measurements listed above for a given site could be estimated at being greater than 1,000 hours per tower site, per year. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (te6npp.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (te6npp.def). 8. Data Organization 8.1 Data Granularity All of the NPP Estimates for the BOREAS TF, CEV, and AUX Sites data are contained in one dataset. 8.2 Data Format(s) The data files contain a series of numerical and character fields of varying length separated by commas. The character fields are enclosed in single apostrophe marks. Sample data records are shown in the companion data definition file (te6npp.def). 9. Data Manipulations 9.1 Formulae 9.1.1 Derivation Techniques and Algorithms Tree biomass is calculated from a diameter measurement and an allometric equation and then scaled to the hectare level using a plot scaling factor that reflects the tree's representative size in relation to the plot size (Dilworth and Bell, 1979). Allometric equations are generally developed on a log-log basis to correct for nonhomogeneous variance (see BOREAS TE-06 Allometry Data documentation). Biomass by component (Kg/ HA) = (INVLOG(a + b (LOG (diameter)))) * PLOT SCALING FACTOR Tree increment (multiplied by 2 and corrected for a tree bark thickness of 0.1 cm) is then subtracted from or added to the original diameter measurement (depending on when the tree diameter was measured and tree core taken) to develop an estimate of another year's diameter. 1993 diameter = 1994 measured diameter - 1993 measured increment Biomass is then calculated for two consecutive years, and the difference between the two is considered the overstory increment. Overstory Increment = 1994 Biomass by component - 1993 Biomass by component For determining litterfall mass by component at the tower sites, screens are averaged by plot and scaled to the hectare level. The stand average is then determined and added to the overstory biomass increment. 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 Not applicable. 9.3.2 Calculated Variables See Section 9.1.1. 9.4 Graphs and Plots Not applicable. 10. Errors 10.1 Sources of Error The greatest potential source of error other researchers need to be aware of for the TF sites is not from the data collection or calculation but from differences in vegetation between where other researchers may have worked and where the TE- 06 team located its plots. Researchers should contact Tom Gower if they feel plot location may be affecting any corroboration between their estimates and these. The variability for fine root production is high for these estimates, as is the case for most estimates of fine root production. It is likely that this variation is a reflection of the variability within boreal forests. The estimates for overstory root increment are based on generalized equations and are not all species specific, but problems surrounding this usage are likely minimal (Santantonio, D. et al., 1980) For the aux sites, difficulty surrounding the efficacy of non-site-specific allometric equations in estimating biomass and overstory biomass increment values occurs at a number of sites. Estimating overstory biomass increment from non-site-specific equations for wood and branch increment is problematic when the diameters of the trees measured are smaller or larger than the diameters of the trees that were harvested to develop the allometric equation. For this reason, the biomass for trees at the AUX and CEV sites that had a diameter that was either too large or small for the TF allometric equations was estimated from the Singh (1982) equations. 10.2 Quality Assessment The data provided are of generally good quality with the above considerations taken into account. 10.2.1 Data Validation by Source It is not possible to validate the data without developing new allometric equations and/or installing new plots. A check was performed using published allometric equations (Singh, 1982) and there was generally good agreement for total biomass increment at all sites, but poor agreement for foliage increment, which is not unexpected. 10.2.2 Confidence Level/Accuracy Judgment Confidence level for the TF sites is high for the data submitted and slightly less so for some aux sites. Researchers should note Section 10.1. 10.2.3 Measurement Error for Parameters Not applicable. 10.2.4 Additional Quality Assessments Not applicable. 10.2.5 Data Verification by Data Center Data were examined for general consistency and clarity. 11. Notes 11.1 Limitations of the Data The CEV and AUX increment estimates are limited to a 30 x 30 m area surrounding a point located using a global positioning system. The location of these points can be found in the STAFF directory of BORIS. 11.2 Known Problems with the Data The overstory increment numbers provided for 1985-1992 and 1986-1993 at the TF/CEV and AUX sites likely decrease in accuracy as one projects back in time (see Section 10.1). 11.3 Usage Guidance None. 11.4 Other Relevant Information None. 12. Application of the Data Set NPP is both the result of and the precursor to a number of important dynamics within the boreal forest that may determine whether this forest type is a sink or source of carbon dioxide in future climate change scenarios. The estimates provided by this effort also provide a means of validation for models that develop carbon budgets for these forests. 13. Future Modifications and Plans Estimates for the 1996 overstory increment and litterfall data may be available please contact Investigator listed in section 2.1. 14. Software 14.1 Software Description None given. 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 The TE-06 NPP 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 Chen, J.M., P.M. Rich, S.T. Gower, J.M. Norman, and S. Plummer. 1997. Leaf area index of boreal forests: Theory, techniques and measurements. J. Geophys. Res. (in press). Dilworth, J.R. and J.F. Bell. 1979. Variable probability sampling-variable plot and three-P. O.S.U. Book Stores, Inc. Corvallis, Oregon. Gower, S.T., J.G. Vogel, T.K. Stow, J.M. Norman, C.J. Kucharik, and S.J. Steele. 1997. Carbon distribution and aboveground net-primary production of BOREAS tower flux forest. J. Geophys. Res. BOREAS Special Issue. Santantonio, D., R.K. Hermann, and W.S. Overton. 1977. Root biomass studies in forest ecosystems. Pedobiologia. 17:1-31. 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.and F. Hall. 1997. BOREAS Overview Paper. JGR Special Issue. Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPSDOC 94). Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPSDOC 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 earlyresults from the 1994 field year. Bulletin of the American Meteorological Society. 76(9):1549-1577. Singh, T. 1982. Biomass equations for Ten Major Tree Species of the Prairie Provinces. Information Report NOR-X-242, Northern Forest Research Centre, Canadian Forestry Service, Environment Canada, Edmonton. Smucker, A. J., S.L. McBurney, and A.K. Srivastava. 1982. Quantitative separation of roots from compacted soil profiles by the hydropneumatic elutriation system. Agron. J. 74:500-503. Steele, S.J., Gower S.T., Vogel J.G., and Norman J.M. 1997. Root mass, net primary production and turnover in aspen, jack pine and black spruce forests in Saskatchewan and Manitoba, Canada. Tree Physiol. (in press). 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None given. 19. List of Acronyms ANPP - Aboveground NPP AUX - Auxiliary site BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System CEV - Carbon Evaluation site DAAC - Distributed Active Archive Center EOS - Earth Observing System EOSDIS - EOS Data and Information System GSFC - Goddard Space Flight Center NPP - Net Primary Productivity 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 SSA - Southern Study Area TE - Terrestrial Ecology TF - Tower Flux site URL - Uniform Resource Locator WAB - Wind-Aligned Blob 20. Document Information 20.1 Document Revision Date Written: 14-Apr-1997 Last Updated: 01-Jul-1998 20.2 Document Review Date(s) BORIS Review: 12-Jun-1997 Science Review: 26-Jun-1998 20.3 Document ID 20.4 Citation Researchers using the data from the TF sites should cite Gower et al., 1997. 20.5 Document Curator 20.6 Document URL Keywords Net primary production Respiration Litter TE06_NPP.doc 07/07/98