BOREAS HYD-03 Tree Measurements Summary The BOREAS HYD-03 team collected several data sets related to the hydrology of forested areas. This data set contains measurements of canopy density (closure), stem density, and diameter at breast height (DBH) from a variety of sites. Canopy density measurements were made during the FFC-W and FFC-T 1994 in both the SSA and NSA. Stem density measurements were made during FFC-W 1996 in the SSA only. Canopy density measurements were made using a forest densiometer, while measurements of stem density and DBH were made using standard techniques. This study was undertaken to predict spatial distributions of energy transfer, snow properties important to the hydrology, remote sensing signatures, and transmissivity of gases through the snow and their relation to forests in boreal ecosystems. 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 HYD-03 Tree Measurements 1.2 Data Set Introduction This data set contains measurements of canopy density (closure), stem density, and DBH from a variety of sites. Canopy density measurements were made during the FFC-W and FFC-T 1994 in both the SSA and NSA. Stem density measurements were made during FFC-W 1996 in the SSA only. Canopy density measurements were made using a forest densiometer, while measurements of stem density and DBH were made using standard techniques. 1.3 Objective/Purpose This study was undertaken to predict spatial distributions of energy transfer, snow properties important to the hydrology, remote sensing signatures, and transmissivity of gases through the snow and their relation to forests in boreal ecosystems. 1.4 Summary of Parameters Parameters measured with respect to this documentation are canopy density (closure), stem density, and DBH. 1.5 Discussion This study was conducted under the hypothesis that energy transfer and snow water equivalent (SWE) would vary spatially as a function of canopy closure. The goal was to obtain canopy closure data for determining either an average closure of a forest or the closure at a specific location (i.e., over a radiometer). Data were compared with canopy data obtained from aerial photography. Stem density data were used in calibrating a radiative transfer model for predicting incoming solar radiation at the snow surface in forested environments. 1.6 Related Data Sets BOREAS Forest Cover Data Layers of the NSA-MSA in Raster Format 2. Investigator(s) 2.1 Investigator(s) Name and Title Robert E. Davis, Research Physical Scientist U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) 2.2 Title of Investigation Distributed Energy Transfer Modeling in Snow and Soil for Boreal Ecosystems 2.3 Contact Information Contact 1 ------------ Janet P. Hardy U.S. Army CRREL Hanover, NH (603) 646-4306 (603) 646-4278 (fax) jhardy@crrel.usace.army.mil Contact 2 ----------- Dr. Robert E. Davis U.S. Army CRREL Hanover, NH (603) 646-4219 (603) 646-4278 (fax) bert@crrel.usace.army.mil Contact 3 ----------- David Knapp NASA GSFC Greenbelt, MD (301) 286-1424 (301) 286-0239 (fax) David.Knapp@gsfc.nasa.gov 3. Theory of Measurements The forest densiometer is used to obtain a quick measurement of overstory density at a point. The instrument consists of a convex mirror with 24 1/4" squares engraved on the surface. The mirror faces up, and the geometry of the overstory above is superimposed on the etched grid on the mirror. Canopy overstory is measured as described below. Stem density is determined by counting the number of stems in a given area. DBH is determined by measuring the circumference of the tree at breast height and converting it to diameter, or by using a tape measure that is pre-calibrated to DBH based on circumference. 4. Equipment 4.1 Sensor/Instrument Description Forest densiometer. 4.1.1 Collection Environment Data were collected during winter conditions. 4.1.2 Source/Platform Densiometer is hand-held. 4.1.3 Source/Platform Mission Objectives The measurements of canopy closure and stem density were undertaken primarily to aid in the snow melt modeling effort. Stem density measurements were made at the location of the subcanopy radiation measurement. This information is valuable for calibrating the model used to estimate subcanopy solar irradiance. 4.1.4 Key Variables Canopy closure, stem density. 4.1.5 Principles of Operation Canopy Density: The forest densiometer is used to obtain a quick measurement of overstory density at a point. The instrument consists of a convex mirror with 24 1/4" squares engraved on the surface. The mirror faces up, and the geometry of the overstory above is superimposed on the etched grid on the mirror. Canopy overstory is measured as described in Section 5. 4.1.6 Sensor/Instrument Measurement Geometry Not applicable. 4.1.7 Manufacturer of Sensor/Instrument Densiometer: Manufacturer: Dr. Paul E. Lemmon Distributor: Forestry Suppliers, Inc. 205 West Rankin St. P.O. Box 8397 Jackson, MS 39284-8397 (800) 647-5368 4.2 Calibration Not applicable. 4.2.1 Specifications Not available. 4.2.1.1 Tolerance Not available. 4.2.2 Frequency of Calibration Not applicable. 4.2.3 Other Calibration Information A report by Ganey and Block, 1994 (complete reference given in Section 17.1), compared the densiometer with another technique for measuring canopy density. Although they were unable to determine which technique provided the most accurate measurement, they believe that for point measurements the densiometer is the best available “quick and easy” method. They did conclude, however, that the densiometer can yield different results when used by different observers. This problem was minimized in these data (see Section 10.1). 5. Data Acquisition Methods Canopy Density: Once sites were located, the densiometer was used to determine the canopy density at that site. The densiometer was held at waist height and far enough from the observer’s body so that his or her head was not visible in the mirror. The instrument was then leveled using the built-in bubble level. For each of the 24 etched squares, the square was divided into quarters and the number of quarter sections covered by canopy (1, 2, 3, or 4) was counted. The total number of quarter sections was recorded (up to 96 possible). Keeping the densiometer in the same location, the observer then rotated 90 degrees and counted again. This process was repeated until the canopy closure sections were counted in all four directions, and the four totals were recorded. The average of the four totals, was then multiplied by 1.04 to determine the canopy closure at that site (see formula in Section 9.1). Stem Density: To obtain a measurement of stem density, the area was measured and marked (e.g., 20 m x 25 m), and every stem inside the marked area was counted. The number of stems was divided by the area to get the stem density (see formula in Section 9.1). DBH: In the case of the Southern Study Area (SSA)-Old Aspen (OA) site, the diameter at breast height (DBH) of each tree in the marked area was also measured. 6. Observations 6.1 Data Notes None. 6.2 Field Notes None. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage Canopy Density: The canopy density measurements were collected at the following approximate locations: SITE_ID LONGITUDE LATITUDE ------------------------- ---------- ---------- SSA-OJP-FLXTR-HYD03-CND01 -104.69203 53.91634 NSA-OJP-FLXTR-HYD03-CND02 -98.62028 55.93011 NSA-OBS-FLXTR-HYD03-CND02 -98.48027 55.8801 NSA-YJP-FLXTR-HYD03-CND04 -98.29027 55.90011 NSA-YJP-FLXTR-HYD03-CND03 -98.29027 55.90011 NSA-YJP-FLXTR-HYD03-CND01 -98.29027 55.90011 NSA-OJP-FLXTR-HYD03-CND03 -98.62028 55.93011 NSA-OBS-FLXTR-HYD03-CND01 -98.48027 55.8801 NSA-OBS-FLXTR-HYD03-CND03 -98.48027 55.8801 NSA-YJP-FLXTR-HYD03-CND02 -98.29027 55.90011 SSA-999-NIB01-HYD03-CND02 -104.59484 53.75285 SSA-999-NIB01-HYD03-CND03 -104.59484 53.75285 SSA-9OA-FLXTR-HYD03-CND01 -106.19051 53.63005 NSA-9BS-HYD3A-HYD03-CND01 -97.89026 55.81011 NSA-YBS-HYD03-HYD03-CND02 -97.87026 55.83011 NSA-MIX-HYD03-HYD03-CND03 -97.84025 55.85011 NSA-9BS-HYD3B-HYD03-CND04 -97.82025 55.87011 SSA-BSH-110G1-HYD03-CND01 -105.81221 54.52526 SSA-ASP-110H1-HYD03-CND01 -105.8067 54.50956 SSA-999-110I1-HYD03-CND01 -105.8098 54.49536 SSA-BRN-110J1-HYD03-CND01 -105.8123 54.48146 SSA-ASP-110K1-HYD03-CND01 -105.81 54.46696 SSA-CLR-110L1-HYD03-CND01 -105.8024 54.43746 NSA-OJP-FLXTR-HYD03-CND01 -98.62028 55.93011 SSA-YJP-122D1-HYD03-CND01 -104.61914 53.84426 SSA-999-122E1-HYD03-CND01 -104.61944 53.84916 SSA-MIX-122F1-HYD03-CND01 -104.62214 53.85586 SSA-MIX-122G1-HYD03-CND01 -104.60623 53.89836 SSA-MIX-HYD03-HYD03-CND0A -104.58044 53.80006 SSA-MIX-HYD03-HYD03-CND0T -104.58044 53.80006 SSA-MIX-HYD03-HYD03-CND0S -104.58044 53.80006 SSA-999-NIB01-HYD03-CND01 -104.59484 53.75285 SSA-9JP-110A1-HYD03-CND01 -105.83864 54.60117 SSA-MIX-110B1-HYD03-CND01 -105.82606 54.58848 SSA-MIX-110C1-HYD03-CND01 -105.82461 54.57386 SSA-MIX-110D1-HYD03-CND01 -105.81851 54.56146 SSA-ASP-110E1-HYD03-CND01 -105.81461 54.54696 SSA-ASP-110F1-HYD03-CND01 -105.81301 54.53426 The stem density measurements were made near the SSA-Old Black Spruce (OBS) and SSA-OA towers. DBH was also measured at the SSA-OA site. SITE_ID LONGITUDE LATITUDE ------------------------- ---------- ---------- SSA-9OA-FLXTR-HYD03-STD01 -106.19779 53.62889 SSA-OBS-FLXTR-HYD03-STD01 -105.11779 53.98717 7.1.2 Spatial Coverage Map Not available. 7.1.3 Spatial Resolution Canopy density: The areas over which measurements of canopy density were made range from 25 to 500 square meters. Stem density: At the SSA-OBS and SSA-OA sites, the area covered was approximately 500 square meters. The DBH was measured only at the SSA-OA site. 7.1.4 Projection These data were collected at various points whose coordinates are given in latitude and longitude in the North American Datum of 1983 (NAD83). 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Focused Field Campaign-Winter (FFC-W) and Focused Field Campaign-Thaw (FFC-T) 1994 (Canopy Density) FFC-W 1996 (Stem Density) 7.2.2 Temporal Coverage Map Canopy Density Dates Site ----------- ------ 07-FEB-1994 Montreal Lake 08-FEB-1994 SSA-Old Jack Pine (OJP), SSA-Young Jack Pine (YJP) 09-FEB-1994 SSA Highway 106 at Triple Junction 10-FEB-1994 SSA-OA 13-FEB-1994 NSA Gillam Road 14-FEB-1994 NSA-YJP 15-FEB-1994 NSA-OJP 16-FEB-1994 NSA-OBS 24-APR-1994 NSA-OBS 26-APR-1994 NSA-YJP Stem Density Dates Site ----------- ------ 03-MAR-1996 SSA-OBS 08-MAR-1996 SSA-OA DBH Dates Site ----------- ------ 08-MAR-1996 SSA-OA 7.2.3 Temporal Resolution In most cases, these measurements were taken only one time for each site. 7.3 Data Characteristics Data characteristics are defined in the companion data definition files (h03candd.def), (h03stdnd.def), and (h03dbhd.def). 7.4 Sample Data Record Sample data format shown in the companion data definition files (h03candd.def), (h03stdnd.def), and (h03dbhd.def). 8. Data Organization 8.1 Data Granularity All of the Tree Measurement Data are contained in three datasets. 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 files (h03candd.def), (h03stdnd.def), and (h03dbhd.def). 9. Data Manipulations 9.1 Formulae Canopy Closure = Average of four counts x 1.04 = canopy closure (%) Stem Density = Number of stems in measured area divided by measured area 9.1.1 Derivation Techniques and Algorithms None. 9.2 Data Processing Sequence None, other than what is indicated above. 9.2.1 Processing Steps Use formula above to calculate canopy density 9.2.2 Processing Changes Not applicable. 9.3 Calculations 9.3.1 Special Corrections/Adjustments Not applicable. 9.3.2 Calculated Variables None. 9.4 Graphs and Plots Not applicable. 10. Errors 10.1 Sources of Error Different operators of the densiometer may produce different results, depending on the operator’s familiarity with the technique. For this reason, the canopy density data were consistently measured by the same person. The other potential error is in the ability of the operator to hold the densiometer level during a measurement. Ganey and Block (1994) suggest using a tripod to reduce error caused by observer movement. For this study, a tripod was not used in measurements of canopy density. 10.2 Quality Assessment 10.2.1 Data Validation by Source Aerial photography and forest cover data of the BOREAS Northern Study Area (NSA), provided by Manitoba Natural Resources of Winnipeg, were used to confirm measured canopy closures. BORIS staff used the forest cover data set is at a scale of 1:15,840, to extract and grid the species cover and crown closure. Image analysis classified the YJP forest in the canopy closure class "31 to 50 %", and the OJP and OBS forests both fell in the canopy closure class of "71% and over." Canopy closure measurements using the densiometer compared favorably with those determined from the aerial photo data (NSA, YJP = 42%; NSA, OJP = 86%; and NSA, OBS = 83%). 10.2.2 Confidence Level/Accuracy Judgment The confidence level and accuracy of the canopy closure measurements is dependent on scale. One measure of canopy closure at a point, with its associated spatial resolution, provides a reliability of about +/-1.3% (Lemmon, 1957). To accurately characterize a forest canopy closure, several measurements with the densiometer should be made to account for the natural variability. The more measurements made, the greater the confidence in the data. 10.2.3 Measurement Error for Parameters Not available. 10.2.4 Additional Quality Assessments Not applicable. 10.2.5 Data Verification by Data Center Data that was loaded into the data tables were spot checked against the original ASCII data that was submitted to check for data loading errors. 11. Notes 11.1 Limitations of the Data These data were collected in winter. Canopy closure measurements in deciduous forests will be very different when leaves are on the trees. 11.2 Known Problems with the Data None. 11.3 Usage Guidance None given. 11.4 Other Relevant Information None given. 12. Application of the Data Set This data set provides data specific to selected sites for the purpose of calibrating radiative transfer and snow melt models. It may also be used as "ground truth" for comparison with forest cover maps. 13. Future Modifications and Plans None given. 14. Software 14.1 Software Description An undetermined spreadsheet software package was used to organize the data. 14.2 Software Access None given. 15. Data Access (This section for BORIS and ORNL DAAC Use) 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. visit. 15.4 Data Center Status/Plans The HYD-03 tree measurement data are available from the EOSDIS ORNL DAAC (Earth Observing System Data and Information System) (Oak Ridge National Laboratory) (Distributed Active Archive Center). 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 Contact BORIS staff. 16.2 Film Products None. 16.3 Other Products Contact BORIS staff. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Ganey, J.L., W.M. Block. 1994. A comparison of two techniques for measuring canopy closure, Western Jour. Appl. Forestry 9(1)21-23. Lemon, P.E. 1957. A new instrument for measuring forest overstory density. Journal of Forestry, 55(9)667-668. Lemon, P.E. 1956. A spherical densiometer for estimating forest overstory density. Forest Science, 2(4)314-320. 17.2 Journal Articles and Study Reports Davis, R.E., C. Woodcock, and J.P. Hardy. 1996. Toward spatially distributed modeling of snow in the boreal forest. Eos Transactions, AGU 1995 Fall Meeting, Abstract, p. 218. Davis, R.E., J.P. Hardy, W. Ni, C. Woodcock, C.J. McKenzie, R. Jordan, and X. Li. 1997. Variation of snow ablation in the boreal forest: A sensitivity study on the effects of conifer canopy. Journal of Geophysical Research. 102(D24):29389-29396. Hardy, J.P., R.E. Davis, and G.C. Winston. 1995. Evolution of factors affecting gas transmissivity of snow in the boreal forest. In: Biogeochemistry of Seasonally Snow-Covered Catchments (ed. by K. Tonnessen, M.W. Williams, and M. Tranter) (Proc. Boulder Symp., July 1995). IAHS publication no. 228, p. 51-60. Hardy, J.P., R.E. Davis, and R. Jordan. 1996. Snow melt modeling in the boreal forest. Eos Transactions, AGU 1996 Fall Meeting, abstract, p. 196. Hardy, J.P., R.E. Davis, R. Jordan, X. Li, C. Woodcock, W. Ni, and J.C. McKenzie. 1997. Snow ablation modeling at the stand scale in a boreal jack pine forest. Journal of Geophysical Research. 102(D24): 29397-29406. 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., 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.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, F.E. Guertin. 1997. BOREAS in 1997: Experiment overview, scientific results, and future directions. Journal of Geophysical Research. 102(D24):28731-28770. 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. Winston, G.C., B.B. Stephens, E.T. Sundquist, J.P. Hardy, and R.E. Davis. 1995. Seasonal variability in gas transport through snow in a boreal forest. In: Biogeochemistry of Seasonally Snow-Covered Catchments (ed. by K. Tonnessen, M.W. Williams, and M. Tranter) (Proc. Boulder Symp., July 1995). IAHS publication no. 228, p. 61-70. 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 BS - Black Spruce CGR - Certified by Group CPI - Checked by Principal Investigator CPI-??? - CPI but questionable CRREL - Cold Regions Research and Engineering Laboratory DAAC - Distributed Active Archive Center DBH - Diameter at Breast Height EOS - Earth Observing System EOSDIS - EOS Data and Information System FFC-W - Focused Field Campaign - Winter FFC-T - Focused Field Campaign - Thaw GMT - Greenwich Mean Time GSFC - Goddard Space Flight Center HYD - Hydrology NAD83 - North American Datum of 1983 NASA - National Aeronautics and Space Administration 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 PRE - Preliminary SSA - Southern Study Area URL - Uniform Resource Locator YBS - Young Black Spruce YJP - Young Jack Pine 20. Document Information 20.1 Document Revision Date Written: 23-Apr-1997 Revised: 19-Mar-1998 20.2 Document Review Date(s) BORIS Review: 12-Mar-1998 Science Review: 15-Jul-1997 20.3 Document ID 20.4 Citation 20.5 Document Curator 20.6 Document URL Keywords CANOPY DENSITY STEM DENSITY DBH HYD03_Tree_Meas.doc Page 14 of 16 04/17/98