Bailey Ecoregions of the Continents (reprojected)
Principal Investigators:
Dr. Robert G. Bailey
USDA Forest Service
Summary:
Ecoregions of the Continents characterizes global potential natural vegetation
at approximately 1/2-degree resolution. The dataset is based on a Russian
vegetation map (Gerasimov, 1964) which was updated by the US Fish and Wildlife
Service (Robert C. Bailey), however the geographic projection was unknown.
This version was reprojected to geodetic coordinates at the World Conservation
Monitoring Center, England.
Primary References:
Bailey, R.G. and H.C. Hogg, 1986. A
world ecoregions map for resource reporting. Environmental Conservation,
Vol. 13, No. 3, pp. 195-202.
Bailey, R.G. 1989. Explanatory supplement
to Ecoregions Map of the Continents. Environmental Conservation,
vol. 16, no. 4, pp 307-309.
Bailey Ecoregions of the Continents
(reprojected)
DATASET DESCRIPTION
Dataset Description
INTEGRATED DATASET
DataSet Citation:
Bailey, R.G. 1989/1993. Bailey Ecoregions of the Continents (reprojected)
from the World Conservation Monitoring Center. Digital vector data on a
0.3 degree resolution Cartesian Orthonormal Geodetic (lat/long) global
polygon network and derived raster data on a 10-minute Cartesian Orthonormal
Geodetic (lat/long) 1080x2160 grid. In: Global Ecosystems Database Version
2.0. Boulder, CO: NOAA National Geophysical Data Center. One independent
spatial layer with three attributes. 10,235,790 bytes in 15 files.
Projection:
Cartesian Geodetic (lat/long)
Spatial Representation:
(1) Vector polygonal classed units at a claimed scale of 1:30,000,000.
(2) 10-minute global 1080x2160 grids rasterized from the vector data
Temporal Representation:
Static modern composite.
Data Representation:
Classes represented in an attribute values file, linked to areas by numerical
code.
Layers and Attributes:
One vector layer with three attributes; with the same data represented
in three dependent single-attribute raster layers.
Dataset Description
DESIGN
Variables:
Bailey's Ecoregions, classed by Domain, Division, and Province.
Origin:
Multiple paper map sources integrated and modified by Robert Bailey.
Geographic Reference:
Undocumented Russian projection based on Gerasimov, I.P. (Ed.) 1964. Types
of natural landscapes of the Earth's land areas. Plate 75, In Fiziko-geograficheskii
Atlas Mira [Physico-geographic Atlas of the World]. USSR Acad. Sci. and
Main Administration of Geodesy and Cartography. Moscow, USSR, scale = 1:80,000,000.
Geographic Coverage:
Global
Maximum Latitude: +90 Degrees (N)
Minimum Latitude: -90 Degrees (S)
Maximum Longitude: +180 Degrees (E)
Minimum Longitude: -180 Degrees (W)
Geographic Sampling:
Vector boundary data from original 1:80,000,000 scale, represented at 1:30,000,000.
Time Period:
Composite of most recent information ca 1960-1980.
Temporal Sampling:
Composite of most recent information ca 1960-1980.
Dataset Description
SOURCE
Source Data Citation:
Bailey, R.G. 1989/1993. Bailey Ecoregions Map of the Continents (reprojected).
Digital vector data on a Geographic (lat/long) global polygon network in
ARC/INFO format. Cambridge, U.K.: World Conservation Monitoring Center.
623 KB in 1 compressed file on floppy disk.
Contributor:
Dr. Mark Collins
World Conservation Monitoring Center
Cambridge, U.K.
Distributor:
World Conservation Monitoring Center
Cambridge, U.K.
Tel: 44 223 277314
Date of Production:
1989
Lineage & Contacts:
-
Original paper map in an undocumented Russian projection:
Dr. Robert G. Bailey
USDA Forest Service
3825 east Mulberry St.
Ft. Collins, CO 80524, USA
-
Digitized by:
Robert Waltermire
National Ecology Research Center
4512 McMurry Ave.
Ft. Collins, CO 80525-3400
-
Resampled to Geographic (lat/long) projection by:
Richard Luxmoore
World Conservation Monitoring Center
Cambridge, U.K.
-
Integrated for GED:
-
John J. Kineman and Mark A. Ohrenschall
NOAA National Geophysical Data Center
325 S. Broadway, E/GC1
Boulder, CO 80303 USA
fax: (303) 497-6513
Email: jkineman@ngdc.noaa.gov
Web: http://www.ngdc.noaa.gov/seg/eco.
Dataset Description
ADDITIONAL REFERENCES
Bailey, R.G. 1983. Delineation of ecosystem regions. Environmental Management,
Vol. 7, No. 4, pp. 365-373.
Bailey, R.G. 1984. Testing an ecosystem regionalization. Journal
of environmental Management, Vol. 19, pp. 239-248.
Bailey, R.G. 1985. The factor of scale in ecosystem mapping. Environmental
Management Vol. 9, No. 4, pp. 271-276.
Bailey, R.G. 1987. Suggested hierarchy of criteria for multi-scale ecosystem
mapping. Landscape and Urban Planning, Vol. 14, pp. 313-319.
Bailey, R.G. 1983. Delineation of ecosystem regions. Environmental
Management, Vol. 7, No. 4, pp. 365-373.
Bailey, R.G. 1984. Testing an ecosystem regionalization. Journal
of environmental Management, Vol. 19, pp. 239-248.
Bailey, R.G. 1985. The factor of scale in ecosystem mapping. Environmental
Management Vol. 9, No. 4, pp. 271-276.
Bailey, R.G. 1987. Suggested hierarchy of criteria for multi-scale ecosystem
mapping. Landscape and Urban Planning, Vol. 14, pp. 313-319.
Bailey, R.G. 1991. Design of ecological networks for monitoring global
change. Environmental Conservation, Vol. 18, No. 2, pp. 173-176.
Gerasimov, I.P. (Ed.) 1964. Types of natural landscapes of the Earth's
land areas. Plate 75. In Fiziko-geograficheskii Atlas Mira [Physical-geographic
Atlas of the World]. USSR Academy of Sciences, Institute of Geodesy and
Cartography, Moscow. Scale = 1:80,000,000.
Dataset Description
FILE LISTS
Bailey Ecoregions of the Continents
(reprojected)
DATASET ELEMENT DESCRIPTIONS
Ecoregion Province
Description:
Bailey Ecoregions of the Continents (Province) reprojected by resampling
from an undocumented projection to geodetic coordinates at the World Conservation
Monitoring Center using coastal control points.
Structure:
Vector polygon file in a Geodetic
(latitude/longitude) reference system: 1/2 degree resolution
Raster data file: 10-minute Cartesian
Geodetic (latitude/longitude) 1080x2160 grid
Series:
none
System Files:
Notes:
-
The attribute table is provided as a Microsoft Access 2.0 database and
as an ASCII text table.
-
Rasterized from the DLG vector polygons (stored in the SOURCE directory)
and the attribute table
-
The vector map included with the main dataset contains unlabled polygons
for visual overlay, and is therefore labeled as a "line" type.
-
Legend includes Domain and Division names
Ecoregion Domain
Description:
Bailey Ecoregions of the Continents (Domain) reprojected by resampling
from an undocumented projection to geodetic coordinates at the World Conservation
Monitoring Center using coastal control points.
Structure:
Raster data file: 10-minute Cartesian
Geodetic (latitude/longitude) 1080x2160
Series:
Hierarchical classifications
System Files:
Notes:
-
The attribute table is provided as a Microsoft Access 2.0 database and
as an ASCII text table.
-
Rasterized from the DLG vector polygons (stored in the SOURCE directory)
and the attribute table
-
The vector map included with the main dataset contains unlabled polygons
for visual overlay, and is therefore labeled as a "line" type.
-
Legend includes Domain and Division names
Ecoregion Division
Description:
Bailey Ecoregions of the Continents (Division) reprojected by resampling
from an undocumented projection to geodetic coordinates at the World Conservation
Monitoring Center using coastal control points.
Structure:
Raster data file: 10-minute Cartesian
Geodetic (latitude/longitude) 1080x2160 grid
Series:
none
System Files:
Notes:
-
The attribute table is provided as a Microsoft Access 2.0 database and
as an ASCII text table.
-
Rasterized from the DLG vector polygons (stored in the SOURCE directory)
and the attribute table
-
The vector map included with the main dataset contains unlabled polygons
for visual overlay, and is therefore labeled as a "line" type.
-
Legend includes Domain and Division names
Bailey Ecoregions of the Continents
(reprojected)
TECHNICAL REPORTS
Original Documentation
Data Integration Report
Technical Report
Original Documentation:
US Fish and Wildlife Service
The National Ecology Research Center digitized the Ecoregions of the Continents
map (Robert G. Bailey, U.S. Department of Agriculture, Forest Service,
Washington, 1989) at a scale of 1:30,000,000 from a paper source. Arc/Info
Version 5.01 software was used to digitize the map in table inches using
an Altek Model 34.3 tablet with a resolution of .001" (.0254 mm) and an
accuracy of +/- .003" (+/- .08 mm).
The following information is extracted from documentation of November
27, 1990 for the "ECOREGIONS OF THE CONTINENTS DATA BASE" distributed with
the original version of the dataset by the National Ecology Research Center,
U.S. Fish and Wildlife Service, 4512 McMurray Avenue, Ft. Collins, CO 80525-3400:
"The center was unable to determine which [projection] was used.
Since the projection and specific parameters of the source map are unknown,
it is not possible to accurately transform the ECOWRLD coverage to projected
units. USERS OF THE ECOWRLD COVERAGE (in table inches) ARE ADVISED THAT
THE NATIONAL ECOLOGY RESEARCH CENTER ASSUMES NO RESPONSIBILITY FOR A TRANSFORMATION
OF THE EXISTING COVERAGE OR FOR RESULTS OBTAINED FROM A RUBBER SHEETING
PROCESS.
Rubber sheeting can be applied if a generous number of control points
are used. The accuracy of the final product, however, may still be in question
depending on the number and accuracy of the links used (Andrew Duff, ESRI,
personal communication)."
WCMC Documentation:
Documentation supplied with the WCMC version provides the following information:
Information Content
Digital data obtained from the Ecology Research Center, US Fish and Wildlife
Service. The data has been digitized in table inches using an Altek Model
34-3 tablet with a resolution of 0.254 mm and an accuracy of +/- .003 inches
(+/-) .08 mm) in ARC/INFO v.5.01. The projection of the map was unknown,
although tic locations were provided. The transformation of the tic points
was unsuccessful so the data [were] transformed up to World Data[bank]
II and then rubber sheeted using over 7000 links. Rubber Sheeting was applied
at WCMC. The (polygon) data is presented with a single polygon attribute
file for each coverage.
Description of coverage Bailey [from ARC/INFO]:
Precision single
ARCS POLYGONS
Arcs = 1574 Polygons = 633
Segments = 40213 Polygon Topology is present
0 bytes of Arc Attribute Data 186 bytes of Polygon Attribute Data
NODES POINTS
Nodes = 1599 Label Points = 632
0 bytes of Node Attribute Data
TOLERANCES SECONDARY FEATURES
Fuzzy = 0.006 V Tics = 288
Dangle = 0.000 N Links = 0
COVERAGE BOUNDARY
Xmin = -180.000 Ymin = -90.000
Xmax = 180.000 Ymax = 90.000
COORDINATE SYSTEM DESCRIPTION
Projection GEOGRAPHIC
Units DD Spheroid CLARK1866
The following table lists the original control points from NERC and
those provided in the WCMC reprojected coverage:
IDTIC XTIC(Orig) YTIC(Orig) XTIC(WCMC) YTIC(WCMC)
1 -180 60 -.1799959E+03 0.5999799E+02
2 0 80 0.0000000E+00 0.7999663E+02
3 80 80 0.7999514E+02 0.7999663E+02
4 180 60 0.1799959E+03 0.5999799E+02
5 160 20 0.1599998E+03 0.1999937E+02
6 160 -20 0.1599998E+03 -19.999370
7 180 -60 0.1799959E+03 -59.997990
8 120 -80 0.1199927E+03 -79.996630
9 -20 -80 -19.998790 -79.996630
10 -180 -60 -179.995900 -59.997990
11 -140 -20 -139.999800 -19.999370
12 -140 20 -.1399998E+03 0.1999937E+02
13 -40 20 -.3999995E+02 0.1999937E+02
14 80 20 0.7999991E+02 0.1999937E+02
15 80 -20 0.7999991E+02 -19.999370
16 -40 -20 -39.999950 -19.999370
This suggests agreement to about three decimal places, however it is uncertain
if the WCMC tic coordinates are those reprojected from original table inches
after determining the rubber sheeting parameters, or if they were used
as part of the control point array (in which case the agreement could not
be taken as a general result for the overall map).
Technical Report
DATA INTEGRATION REPORT
John J. Kineman
National Geophysical Data Center
Boulder, CO 80303
Source Data:
.The source dataset was obtained through Mark Collins of the World Conservation
Monitoring Center in U.K. following various unsuccessful attempts to unproject
the original digital version provided to us by the National Ecology Research
Laboratory (Digitized by Robert Waltermire from Robert Bailey's original
map). The original map was thought to conform to an unknown Ginsberg modified
Polyconic projection, but we were only able to confirm that it is based
on a Russian projection used in the Gerasimov atlas (see Additional References,
above). A copy of the Gerasimov atlas resides at NGDC in Boulder, and NGDC
has close contacts with the cartographic institute which produced the atlas
(part of the former USSR Academy of Sciences in Moscow). These contacts
provided the following information about the projection used for Plate
75 of the atlas (which was apparently the base map for Bailey's work):
1. The projection is a modified polyconic projection of the USSR Geodetic
and Cartographic Institute (Academy of Sciences).
2. In 1971 the projection was approximated at the institute by computer
analysis using 9th order polynomials in latitude and longitude, with control
points on a 5 degree grid. Otherwise, there is no known mathematical transformation.
The polynomial approximation techniques developed in Moscow for reprojection
are similar to most rubber-sheeting methods (which also use polynomial
approximation). Since the WCMC version was already done, and was kindly
made available for the project, we decided to use that version.
Data Integration:
The WCMC version of the Bailey's Ecoregions dataset was provided to us
from WCMC on floppy disk as an Arc/Info Export file in compressed format,
and was exported from PC Arc/Info v.3.4D Plus to Idrisi 4.0 preserving
coordinate precision to three decimal places and using region codes created
from unique combinations of fields in the attribute table. Thus BEC.VEC
is a vector data file with polygon IDs corresponding to codes that were
assigned for each of the Bailey Ecoregion classes. The codes were created
by numbering the unique occurrences of Domain, Division, and Province in
the dataset. The resulting vector polygon file was also rasterized into
a 10-minute global image file (BEC.IMG) in the GED format (see User's Guide).
The attributes Domain and Division were similarly coded from the Polygon
Attribute Table and assigned to the Ecoregions map to produce derived raster
layers. Both BECDOM and BECDIV are thus simple reclassifications of BEC.
Since the Province attribute is essentially the same as the BEC classes,
a separate image/map was not created for it. The descriptive legend for
the numerically coded classes in BEC was created by combining the information
for Domain, Division, and Province from the attribute table.
The vector polygon file produced for rasterization using the "DLG" procedure
is included in the SOURCE directory. This file contains "reverse-digitized"
hole polygons.
The vector file included in the main dataset (not the Source directory)
was created using the "Ungenerate" command in Arc/Info, however it does
not contain the same ID values described above. It is therefore documented
in the metadata file (BEC.DVC) as a "line" file, rather than a polygon
file. In fact the lines are closed polygons, but not labeled as above.
It is provided for visual overlay, whereas the DLG produced file stored
in the SOURCE directory should be used for rasterizing or linking to the
attribute table. The "Ungenerate" procedure produces a vector polygon map
that does not "reverse out" the holes. These files are better for visual
overlay (for example in Idrisi) because the connecting lines between parent
and polygon are removed; however, they are less robust for use in rasterizing
because one must be certain that hole polygons follow sequentially in the
file after the parent polygons. If this is not the case, the parent polygon
data will "fill-in" the hole during rasterization.
Quality Control and Testing
Various quality checks were performed during and after the integration
process. First, visual comparisons were made with Micro World Data Bank
II in Arc/Info and Idrisi. Micro World Databank II is the standard georeference
adopted by the GED Project, and is considered acceptable to 2 minute resolution
(.033 deg.). Distance measurements were made in random areas appearing
to have the greatest and/or characteristic disagreement. On this subjective
basis, disagreements along the coast approaching 1-degree were found. This,
however, does not appear to be an error in the re-projection process, since
the MWDBII vectors are far more detailed than the Bailey polygon boundaries
and no systematic or regional patterns of disagreement (i.e., consistent
displacements in one direction or another over a significant region) were
noticeable. Projection errors would be especially evident in the polar
regions in such a visual comparison, but again, the general agreement between
MWDBII coasts and the BEC coasts seemed consistent. Overall registration
differences between the two data sets appeared to be considerably less
than the mean difference between the coastlines, again supporting the hypothesis
that discrepancies were primarily due to the resolution of the Bailey Ecoregion
data, rather than projection or registration errors.
More rigorous statistical comparisons were performed to test the registration
and general agreement with MWDBII coastlines.
Accuracy of Coastline compared to Micro World Data Bank II
Mean distance between coastlines between the Bailey dataset and MWDBII
Coasts were calculated on a 10-minute raster grid by first producing a
distance map from the land/water boundary in the Bailey dataset, then extracting
statistics using the MWDBII coastline as the extraction feature. The results
of this test were:
Mean coastline offset: .22 deg.
Maximum offset: 3.5 deg.
standard deviation of offset: .32 deg.
This indicates that about 90% of the coastal points are within .5 deg.
Registration
Next, registration was tested by perturbing the origin in the above analysis,
so that comparisons were made with a one pixel offset in four orthogonal
directions. The results of this test were:
perturbation mean coastal offset
(x+1, y+1) : .25
(x-1, y-1): .24
(x+1,y-1): .25
(x-1,y+1): .25
Mean coastal offset will increase with increasing mis-registration,
and as expected increased mis-registration occurred in all four directions.
This indicates that no registration error is detectable at 10-minute resolution.
Distance between points along a polygon boundary
As a final check, statistics were produced (using a program developed by
Mark Ohrenschall of NGDC) on the point spacing within the Bailey vector
data. The results of this test were (numerical values below are in units
of degrees):
all points weighted equally means by polygon s.d. by polygon
Mean point spacing: .33 .33 .2
standard deviation: .5 .1 ---
maximum: *8 .9 2.8
* excluding straight lines, which can have point spreads up to 58 degrees.
This indicates about 20 minute resolution at 70% confidence, 30 minute
resolution at 80%, and about 50 minute resolution at 99%. Also, the polygon
resolutions are evenly distributed (mean = mean of polygon means), and
fairly consistent (s.d. of the polygon mean point spacing = .1); although
point spacings approaching 1 deg. were common among polygons. The average
(across polygons) of standard deviations of spacings within polygons was
.2. The maximum s.d. of spacings within a polygon was 2.8.
Conclusion
One must remember that grid resolution, i.e., the spacing or size of raster
cells, is not the same as feature resolution. For a raster representation
of this dataset that does not loose information, a 10-minute grid was necessary,
although the spatial resolution of the data is no better than .5 degree
and may approach 1 degree. This is because resolution of vector data varies
between features, and is different for relative locations of polygon boundaries
than it is for absolute locations or information internal to those boundaries.
A feature resolution of between .3 and .8 deg seems like a good estimate
overall. This is supported by the mean point spacing along lines as well
as the mean locational error of the coastlines. It is interesting how well
this corresponds (assuming a digitizing accuracy of 1 mm) to the mixed
scales, 1:30,000,000 for the original Bailey map and USDA Forest Service
digitized version, and 1:80,000,000 for the Russian data published in the
Gerasimov atlas, which was used as a major source.
For the raster images, representation at 10-minutes was chosen to preserve
boundary relationships and relative detail. A general rule of thumb in
remote sensing is that ground resolution is generally limited to about
2-3 pixels. The same ratio thus exists for a 10-minute raster version of
this dataset (resolvable to only .5 degree information). The difference
between representation and resolution is thus apparent and unavoidable.
The comparisons performed to test resolution and registration show that
the rubber sheeting process performed by WCMC was successful and probably
an order of magnitude more accurate than the data in both projection and
registration. Nevertheless, this was tested only along the coastlines (unless
the tic points were preserved for testing and not used as control points
in the rubber sheeting process - this would have to be confirmed with WCMC).
Position error of the coastline was consistent with the point spacing.