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
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