BOREAS TE-09 NSA Photosynthetic Response Data Summary The BOREAS TE-09 team collected several data sets related to chemical and photosynthetic properties of leaves. This data set describes (1) the response of leaf and shoot-level photosynthesis to ambient and intercellular CO2 concentration, temperature, and incident PAR for black spruce, jack pine, and aspen during the three IFCs in 1994 in the NSA; (2) the response of stomatal conductance to vapor pressure difference throughout the growing season of 1994; and (3) a range of shoot water potentials (controlled in the laboratory) for black spruce and jack pine. The data are available in tabular ASCII files. Table of Contents * 1. Data Set Overview * 2. Investigator(s) * 3. Theory of Measurements * 4. Equipment * 5. Data Acquisition Methods * 6. Observations * 7. Data Description * 8. Data Organization * 9. Data Manipulations * 10. Errors * 11. Notes * 12. Application of the Data Set * 13. Future Modifications and Plans * 14. Software * 15. Data Access * 16. Output Products and Availability * 17. References * 18. Glossary of Terms * 19. List of Acronyms * 20. Document Information 1. Data Set Overview 1.1 Data Set Identification BOREAS TE-09 NSA Photosynthetic Response Data 1.2 Data Set Introduction The response of photosynthesis to ambient CO2 concentration, temperature, light (Photosynthetically Active Radiation (PAR), vapor pressure difference, and shoot water potential was investigated as part of an effort to construct the response surfaces of photosynthesis to different environmental factors. Samples were taken from three forest types: jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana Mill. B.S.J.P), and aspen (Populus tremuloides Michx.) in the BOReal Ecosystem-Atmosphere Study (BOREAS) Northern Study Area (NSA) during each of the three Intensive Field Campaigns (IFCs) in 1994. Measurements were taken under controlled environmental conditions in the laboratory using an open gas exchange system in differential mode. Photosynthesis and related parameters all are expressed on a hemisurface area basis. The shape factors for leaf area calculation are 4 and 4.59, respectively, for black spruce and jack pine. 1.3 Objective/Purpose This data set was collected and prepared to provide the response curves of photosynthesis to (1) ambient and intercellular CO2 concentration, (2) temperature, and (3) PAR in jack pine, black spruce, and aspen in the NSA using a cut-branch technique. Additional data sets were collected and prepared to provide the response curves of photosynthesis and stomatal conductance to water vapor pressure difference for jack pine and black spruce to provide the response of photosynthesis to shoot water potential in jack pine and black spruce in the NSA. 1.4 Summary of Parameters Net photosynthesis, ambient and intercellular CO2 concentration, transpiration, stomatal conductance, temperature, PAR, vapor pressure difference (VPD), water potential. 1.5 Discussion The response of photosynthesis to ambient CO2 concentration, temperature, and light (PAR), the response of stomatal conductance to VPD; and the response of photosynthesis and stomatal conductance to shoot water potential were investigated as part of an effort to construct the response surfaces of photosynthesis to different environmental factors. Samples were taken in the NSA during each of the three IFCs in 1994 from three forest types: old jack pine (OJP), old black spruce (OBS), and old aspen (OA). Measurements were taken under controlled environmental conditions in the laboratory using an open gas exchange system in differential mode. Photosynthesis and related parameters all are expressed on a hemisurface area basis. The shape factors for leaf area calculation are 4 and 4.59, respectively, for black spruce and jack pine. 1.6 Related Data Sets BOREAS TE-09 NSA Photosynthetic Capacity and Foliage Nitrogen Data BOREAS TE-09 PAR and Leaf Nitrogen Data for NSA Species BOREAS TE-09 NSA in situ Diurnal Gas Exchange of Boreal Forest Species 2. Investigator(s) 2.1 Investigator(s) Name and Title Dr. Hank Margolis, Associate Professor 2.2 Title of Investigation Relationship between measures of absorbed and reflected radiation and the photosynthetic capacity of boreal forest canopies and understories. 2.3 Contact Information Contact 1 --------- Dr. Hank Margolis Universite Laval Faculte de foresterie et de geomatique Pavillon Abitibi-Price Sainte-Foy, Quebec, Canada (418) 656-7120 Hank.margolis @sbf.ulaval.ca Contact 2 --------- Dr. Qinglai Dang Lakehead University Faculty of Forestry Thunder Bay Canada P7B 5E1 807-343-8507 807-343-8116 (fax) Qinglai.Dang@flash.lakeheadu.ca Contact 3 --------- Shelaine Curd Raytheon STX Corporation NASA GSFC Greenbelt, MD (301) 286-2447 (301) 286-0239 (fax) shelaine.curd@gsfc.nasa.gov 3. Theory of Measurements During the process of photosynthesis, CO2 is assimilated by green leaves (photosynthesis) while H2O is released into the atmosphere (transpiration). The amount of water released and the amount of CO2 absorbed can be determined by comparing the concentrations of watervapor and CO2 in the air moving into the leaf cuvette and those in the air moving out of the cuvette at a known flow rate. The concentrations of CO2 and watervapor in both incoming and outgoing air streams can be measured using an infra-red gas analyzer (IRGA). The rates of net photosynthesis and transpiration are calculated from the difference in the concentrations of CO2 and water vapor between the input and the output from the leaf cuvette. Stomatal conductance is calculated from transpiration rate and the water vapor gradient between the intercellular space and the bulk air in the cuvette. The water in the xylem is under tension. When the stem of the branch is cut, the water will retreat from the cut surface. When the cut-branch is enclosed in the pressure chamber with the cut surface extruding and pressurized gradually, the xylem water will come back to the cut surface when the pressure is equal to the water potential of the shoot. The pressure inside the pressure chamber, and thus the water potential of the shoot, can be read from a pressure gauge. 4. Equipment 4.1 Sensor/Instrument Description LI-COR 6262IRGA, thermocouples, balance, Decagon AgVision root and leaf analysis system, PMS Model 610 pressure chamber. 4.1.1 Collection Environment Values of major environmental variables are given in the data set for each individual measurement. Upper-canopy branch samples were harvested using a shotgun and were immediately recut under water. The samples were then transported to the laboratory for gas exchange measurement. The cut surfaces of the branches were submerged in water during transport (30 to 50 min) and in the laboratory. Measurements for each species generally took 6 to 10 hours. All samples were kept in the dark but prior to measurement, samples were exposed to saturated light for 2 hours to induce stomatal opening and photosynthetic activity. To test photosynthetic response to CO2 concentration changes, steady- state readings were taken at each CO2 level. An independent set of two samples was used for each two CO2 levels. Ambient CO2 varied from 50 to 900 ppm. To keep a continued supply of water to the branch, the cut surface was kept in contact with water during the entire course of measurement. Saturated light was supplied using two 1,000-watt high-pressure sodium lamps. When ambient CO2 was varied, other environmental conditions were as follows: temperature = 20 +/- 0.58 C; VPD = 0.7 +/- 0.1 kPa; CO2 = 360 +/- 20 ppm. To test photosynthetic response of varied temperature, the air temperature inside the leaf cuvette was controlled using a radiator that was driven by a temperature-controlled water bath. The vapor pressure inside the cuvette was controlled by passing watervapor saturated air through a condenser whose temperature was controlled using another water bath. A independent set of two branches was used for each temperature. The branches were from four different trees and were mixed randomly. Saturated light for the measurement was supplied using two 1,000-watt high- pressure sodium lamps. VPD of the air was controlled at a relatively constant level except at temperatures below 108 C, when there were some technical difficulties in getting a low enough vapor pressure to maintain the desired VPD. Input CO2 concentration was controlled at 360 (+/- 15 ppm). To test photosynthetic response of varied PAR, the measurements started from the highest PAR level and proceeded to darkness. Steady-state readings were taken at each light level. The light source was two 1,000-watt high-pressure sodium lamps. Different levels of light were achieved by using different neutral density filters. The environmental conditions inside the leaf cuvette were as follows: temperature 20 +/- 0.58 C; VPD 0.7 +/- 0.2 kPa; CO2 360 +/- 15 ppm. To test stomatal conductance of varied VPD, all samples were kept in the dark. The samples to be measured, however, were exposed to saturated light for 2 hours prior to measurement to induce stomatal opening and photosynthetic activity. The stability and reliability of the cut-branch technique were tested. Stable measurements for at least 24 hours are possible. Steady-state readings were taken at each VPD level. An independent set of two samples was used for each VPD level. To keep a continued supply of water to the branch, the cut surface was kept in contact with water during the entire course of measurement. Different VPD levels were achieved by regulating the water vapor pressure of the input air stream to the leaf cuvette. Saturated light was supplied using two 1,000-watt high-pressure sodium lamps. The CO2 concentration in the input air was 360 (+/- 15 ppm). Measurements were taken at three temperatures (15, 25, and 358 C) in IFC-1, two temperatures (25, and 358 C) in IFC-2, and at 258 C only in IFC-3. In the laboratory, the branches were taken out of the water, the cut surfaces of the branches were dried and sealed using silicon grease. The branches were then exposed to light and let transpire freely. At certain time intervals, the gas exchange of the branches (two at a time) was measured. The water potential of the branches was measured immediately after the gas exchange measurement. Gas exchange was measured at saturated light conditions. Other environmental conditions in the leaf cuvette were as follows: temperature 20 +/- 0.58 C; VPD 0.7 +/- 0.2 kPa; CO2 of input air 360 +/-15 ppm. 4.1.2 Source/Platform Branch samples were harvested in the early morning using a shotgun and transported to the laboratory in Thompson for gas exchange measurement. 4.1.3 Source/Platform Mission Objectives 1. To obtain the response curves of photosynthesis to ambient and intercellular CO2 concentration, temperature, PAR, leaf-to-airVPD, and shoot water potential. 2. To examine interspecific differences in photosynthetic response to CO2, temperature, PAR, leaf-to-air VPD and shoot water potential. 3. To examine seasonal variations in photosynthetic response to CO2, temperature, PAR, leaf-to-air VPD, and shoot water potential. 4.1.4 Key Variables Net photosynthesis, stomatal conductance, transpiration, ambient and intercellular CO2 concentration, temperature,PAR flux density, VPD, water potential. 4.1.5 Principles of Operation The stems of samples were connected to a water reservoir during the measurement to keep a continuous supply of water to the foliage. Independent samples were used for each temperature level and each sample was measured for two CO2 levels. Samples were exposed to saturated light for 2 hours prior to measurement to induce photosynthetic activity and stomatal opening. Upper-canopy branch samples were harvested using a shotgun and were immediately recut under water. The samples were then transported to the laboratory for gas exchange measurement. The cut surfaces of the branches were submerged in water during transportation (30 to 50 min). In the laboratory, the branches were taken out of the water and the cut surfaces were dried and sealed using silicon grease. The branches were then exposed to light and let transpire freely. At certain time intervals, the gas exchange of the branches (two at a time) was measured. The water potential of the branches was measured immediately after the gas exchange measurement. Gas exchange was measured at saturated light conditions. Other environmental conditions in the leaf cuvette were as follows: temperature 20 +/- 0.58 C; VPD 0.7 +/- 0.2 kPa; CO2 of input air 360 +/-15 ppm. 4.1.6 Sensor/Instrument Measurement Geometry All samples were taken from the upper third of the forest canopy. Efforts were made to keep the amount of foliage relatively consistent from sample to sample. The leaf chamber for the measurement is about 1,300 c in3. 4.1.7 Manufacturer of Sensor/Instrument LI-6200 portable gas exchange system LI-COR P.O.Box 4425, 4421 Superior St., Lincoln, NE 68504 (800)447-3576 Leaf area measurement system/optical image analysis system (AgVision, monochrome system, root and leaf analysis) Decagon Devices, Inc. P.O. Box 835 Pullman, WA 99163 (800)755-2751 Pressure Chamber, Model 610 PMS Instrument Co. 480 SW Airport Avenue Corvallis, OR 97333 (503)752-7926 4.2 Calibration The LI-COR 6262 gas analyzer was calibrated using a standard gas at the beginning of each field campaign. The standard gas had been calibrated against the prime CO2 standard in the NSA laboratory in Thompson, Manitoba, using gas chromatography technique. The stability of gas exchange and the reliability of the cut branch technique were also tested (see Dang et al., 1997a, for details). 4.2.1 Specifications The weighing balance was accurate to within 0.0001 g. The leaf area system was accurate to within 1%. The gas exchange system was accurate to 1 ppm CO2. The shape factor used for black spruce was 4, in accordance with the BOREAS Experiment Plan, Appendix K, Version 3.0. Based on observations of two cross- sections of two needles per fascicle for five fascicles for six jack pine trees from Thompson, Manitoba, an average shape factor of 4.59 (+/- 0.07) was calculated. 4.2.1.1 Tolerance No tolerance level was set for these measurements. 4.2.2 Frequency of Calibration The LI-COR 6262 IRGA was calibrated at the beginning of each IFC. 4.2.3 Other Calibration Information Calibrations were performed according to each manufacturer's instructions. 5. Data Acquisition Methods Upper-canopy branch samples were harvested using a shotgun and were immediately recut under water. The samples were then transported to the laboratory for gas exchange measurement. The cut surfaces of the branches were submerged in water during transport (30 to 50 min) and in the laboratory. Measurements for each species generally took 6 to 10 hours. CO2 concentration variation All samples were kept in the dark, but prior to measurement, samples were exposed to saturated light for 2 hours to induce stomatal opening and photosynthetic activity. Steady-state readings were taken at each CO2 level and an independent set of two samples was used for each two CO2 levels. Ambient CO2 varied from 50 to 900 ppm. To keep a continued supply of water to the branch, the cut surface was kept in contact with water during the entire course of measurement. Saturated light was supplied using two 1,000-watt high-pressure sodium lamps. Other environmental conditions were as follows: temperature = 20 +/- 0.58 C; VPD = 0.7 +/- 0.1 kPa; CO2 = 360 +/- 20 ppm. Temperature variation: The air temperature inside the leaf cuvette was controlled using a radiator that was driven by a temperature-controlled water bath. The vapor pressure inside the cuvette was controlled by passing water vapor-saturated air through a condenser whose temperature was controlled using another water bath. Saturated light for the measurement was supplied using two 1,000-watt high- pressure sodium lamps. VPD of the air was controlled at a relatively constant level except at temperatures below 108 C, when there were some technical difficulties in getting a low enough vapor pressure to maintain the desired VPD. Input CO2 concentration was controlled at 360 (+/- 15 ppm). An independent set of two branches was used for each temperature. The branches were from four different trees and were mixed randomly. PAR variations: The measurements started from the highest PAR level and proceeded to darkness. Steady-state readings were taken at each light level. The light source was two 1,000-watt high-pressure sodium lamps. Different levels of light were achieved by using different neutral density filters. The environmental conditions inside the leaf cuvette were as follows: temperature 20 +/- 0.58 C; VPD 0.7 +/- 0.2 kPa; CO2 360 +/- 15 ppm. Vapor pressure variation: All samples were kept in dark but prior to measurement, samples were exposed to saturated light for 2 hours to induce stomatal opening and photosynthetic activity. The stability and reliability of the cut-branch technique were tested. Stable measurements for at least 24 hours are possible. Steady-state readings were taken at each VPD level. An independent set of two samples was used for each VPD level. To keep a continued supply of water to the branch, the cut surface was kept in contact with water during the entire course of measurement. Different VPD levels were achieved by regulating the water vapor pressure of the input air stream to the leaf cuvette. Saturated light was supplied using two 1,000-watt high-pressure sodium lamps. The CO2 concentration in the input air was 360 (+/- 15 ppm). Measurements were taken at three temperatures (15, 25, and 358 C) in IFC-1, two temperatures (25 and 358 C) in IFC-2, and at 258 C only in IFC-3. Shoot water potential variations: In the laboratory, the branches were taken out of the water and the cut surfaces were dried and sealed using silicon grease. The branches were then exposed to light and let transpire freely. At certain time intervals, the gas exchange of the branches (two at a time) was measured. The water potential of the branches was measured immediately after the gas exchange measurement. Gas exchange was measured at saturated light conditions. Other environmental conditions in the leaf cuvette were as follows: temperature 20 +/- 0.58 C VPD 0.7 +/- 0.2 kPa; CO2 of input air 360 +/-15 ppm. 6. Observations 6.1 Data Notes Three to four leaves per sample for aspen. 6.2 Field Notes Samples were taken from trees of relatively consistent vigor. See pages 2-23 and 2-24 in the BOREAS Experiment Plan, Version 3.0, for a description of site conditions. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage At each site branch samples were taken from four different trees that were at least 10 m apart fromone another. Sampling was done within a 100 m2 area. Locations for each site were: NSA-OJP flux tower site, Lat/Long:55.92842 N, 98.62396 W UTM Zone 14, N:6198176.3, E:523496.2 NSA-OASP canopy access tower site (auxiliary site number T2Q6A, BOREAS Experiment Plan, Version 3), Lat/Long 55.88691 N, 98.67479 W, UTM Zone 14, N: 6193540.7, E: 520342 NSA-OBS flux tower site, Lat/Long: 55.88/007 N, 98.48139 W UTM Zone 14, N: 6192853.4 E: 532444.5 7.1.3 Spatial Resolution These data are point source measurements from the sampled trees. 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage 7.2.1 Temporal Coverage All data were collected between 24-May-1994 and 19-Sep-1994. Samples were taken between 6:00 and 7:00 in the morning. Measurements in the laboratory generally took 6 to 8 hours. An independent data set was taken during each of the three field campaigns. The specific dates for each data set are given in the data table. 7.2.2 Temporal Coverage Map CO2 concentration Site Sample Dates (month-day) 1994 NSA-OBS 04-JUN, 09-AUG, 06-SEP NSA-OJP: 02-JUN, 06-AUG, 07-SEP NSA-OA: 01-JUN, 07-AUG, 30-AUG Temperature: Site Sample Dates (month-day) 1994 NSA-OBS 23-MAY, 26-JUL, 15-SEP NSA-OJP: 13-MAY, 27-JUL, 16-SEP NSA-OA: 14-JUN, 28-JUL, 10-SEP PAR Site Sample Dates (month-day) 1994 NSA-OBS 25-MAY, 23-JUL, 14-SEP NSA-OJP: 26-MAY, 24-JUL, 13-SEP NSA-OA: 10-JUN, 25-JUL, 09-SEP VPD Site Sample Dates (month-day); 1994 NSA-OBS 30-MAY, 25-MAY, 28-MAY, 29-AUG, 30-AUG, 12-SEP NSA-OJP: 24-MAY, 27-MAY, 29-MAY, 01-AUG, 03-AUG, 17-SEP Water Shoot Potential Site Sample Dates (month-day); 1994 NSA-OBS 23-JUL, 06-SEP NSA-OJP: 02-AUG, 07-SEP 7.2.3 Temporal Resolution The measurements can be considered to be single point in time measurements since the same trees were not repeatedly sampled. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (te09prd.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (te09prd.def). 8. Data Organization 8.1 Data Granularity All of the NSA Photosynthetic Response Data are contained in one dataset. 8.2 Data Format(s) The CD-ROM files contain numerical and character fields of varying length separated by commas. The character fields are enclosed with a single apostrophe marks. There are no spaces between the fields. Sample data records are shown in the companion data definition files (te09prd.def). 9. Data Manipulations 9.1 Formulae 9.1.1 Derivation Techniques and Algorithms A, E, gs-CO2 and Ci were calculated according to von Caemmerer and Farquhar (1981), Planta 153: 376-387. WUE = A/E; where WUE=photosynthetic water use efficiency A=net photosynthesis E=transpiration rate VPD = VPsat - Vpamt; where VPD=vapor pressure difference VPsat and VPamt are saturated vapor pressure and measured vapor pressure in the chamber. 9.2 Data Processing Sequence 9.2.1 Processing Steps Data were recorded automatically by a computer and also printed on a printer. Subsequent calculations of different parameters were performed using MS Excel for Windows 5.0. BORIS staff processed the data by: 1) Reviewing the initial data files and loading them online for BOREAS team access. 2) Designing relational data base tables to inventory and store the data. 3) Loading the data into the relational data base tables. 4) Performing the following conversions on measurements into System International (SI) units: - Changing PAR flux from (mol/m2/s) to DOWN_PPFD (umol/m2/s) 5) Working with the Terrestrial Ecology (TE) TE-09 team to document the data set. 6) Extracting the standardized data into logical files. 9.2.2 Processing Changes None. 9.3 Calculations A, E, gs- CO2 and Ci were calculated according to von Caemmerer and Farquhar (1981), Planta 153: 376-387. WUE = A/E VPD = VPsat - Vpamt, where VPsat and VPamt are saturated vapor pressure and measured vapor pressure in the chamber. 9.3.1 Special Corrections/Adjustments None. 9.3.2 Calculated Variables A, E, gs- CO2 and Ci were calculated according to von Caemmerer and Farquhar (1981), Planta 153: 376-387. WUE = A/E VPD = VPsat - Vpamt, where VPsat and VPamt are saturated vapor pressure and measured vapor pressure in the chamber. 9.4 Graphs and Plots Net photosynthesis versus ambient and internal CO2concentration. A, gs, WUE vs. P 10. Errors 10.1 Sources of Error During photosynthetic response to temperature differences, condensation sometimes formed on the radiator inside the cuvette when the temperature went below 108 C. Possible genetic differences between trees and possible differences in physiological conditions between branches could cause inconsisencies in the data. There are no other known sources of error. 10.2 Quality Assessment Please contact Dr. Hank Margolis and Dr. Qinglai Dang if these data are used for publication. (See Section 2.3 Contact Information). 10.2.1 Data Validation by Source After each measurement, the sample was removed from the leaf cuvette and a base measurement (i.e., when cuvette contains no sample) was taken. The previous measurement was adjusted by this base value, if necessary. 10.2.2 Confidence Level/Accuracy Judgment No statistical confidence level is yet available. However, the investigators are very confident that these data are reliable. Results are consistent with field measurements. 10.2.3 Measurement Error for Parameters Unknown. 10.2.4 Additional Quality Assessments Calculated results were plotted, and the patterns were examined. Obvious outliers (determined visually) were eliminated from the data set. 10.2.5 Data Verification by Data Center Data was examined for general consistency and clarity. 11. Notes 11.1 Limitations of the Data None given. 11.2 Known Problems with the Data None. 11.3 Usage Guidance Parameters derived from this data set will be more applicable to aggregated foliage on the shoot as a whole than to individual needles or leaves. 11.4 Other Relevant Information None. 12. Application of the Data Set Data can be used to examine the influence of different factors on the phototsynthetic process. 13. Future Modifications and Plans None. 14. Software 14.1 Software Description Calculations were performed using MS Excel for Windows 5.0. 14.2 Software Access Contact Microsoft Corp. 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-09 photosynthetic response data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The BOREAS contact at ORNL is: ORNL DAAC User Services Oak Ridge National Laboratory (865) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 16. Output Products and Availability 16.1 Tape Products None. 16.2 Film Products None. 16.3 Other Products Tabular ASCII files. 17. References von Caemmerer, S. and G.D. Farquhar, 1981. Some relationships between biochemistry of photosynthesis and the gas exchange of leaves. Planta 153: 376-387. 17.1 Platform/Sensor/Instrument/Data Processing Documentation Li-cor 6262 Infrared gas analyzer manual. 17.2 Journal Articles and Study Reports Dang, Q.L., H. Margolis, M.R. Coyea, M. Sy, and G.J. Collatz. 1997a. Regulation of branch-level gas exchange of boeral trees: roles of shoot water potiential and vapor pressure difference. Tree Physiology, BOREAS Special Issue 17(8/9):521-535. Dang, Q.L., H. Margolis, G.J. Collatz, et al., Paramenterization and testing of a coupled photosynthesis stomatal conductance model for the boreal forest. Tree Physiology (in preparation). 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 (OPSDOC 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. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms A-Ci curve, photosynthetic response to CO2. 19. List of Acronyms A - net photosynthesis ((mol CO2/m2/s) BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System CGI - Certified by Group Ci - intercellular CO2concentration (ppm) CO2 - ambient CO2concentration (ppm) CPI - checked by Principal Investigator DAAC - Distributed Active Archive Center E - transpiration rate (mmol H2O/m2/s) EOS - Earth Observing System EOSDIS - EOS Data and Information System gs CO2 - stomatal conductance to CO2 (mmol/m2/s) GSFC - Goddard Space Flight Center IFC - Intensive Field Campaign IRGA - Infrared Gas Analyzer NASA - National Aeronautics and Space Administration NSA - Northern Study Area ORNL - Oak Ridge National Laboratory P - shoot water potential (MPa) PNP - Prince Albert National Park PAR - photosynthetically active radiation PRE - Preliminary SSA - Southern Study Area Tleaf - leaf temperature (8C) Tair - air temperature (8C) URL - Uniform Resource Locator VPD - Vapor Pressure Difference (kPa) WUE - photosynthetic water use efficiency (mmol CO2/mol H2O) 20. Document Information 20.1 Document Revision Date Written 12-Mar-1996 Last updated 10-Mar-1999 20.2 Document Review Dates BORIS Review: 22-Apr-1997 Science Review: 5-Nov-1997 20.3 Document ID 20.4 Citation Please contact one of the individuals listed in Section 2.3. 20.5 Document Curator 20.6 Document URL Keywords ---------------------- THRESHOLD RESPONSE PHOTOSYNTHETIC RESPONSE WATER POTENTIAL STOMATAL CONDUCTANCE BLACK SPRUCE JACK PINE ASPEN TE09_Photo_Resp 05/07/99