National Land Cover Dataset 1992 - Pennsylvania; Albers Grid


Identification_Information:
Citation:
Citation_Information:
Originator:U.S. Geological Survey (USGS)
Publication_Date:19990527
Title:
National Land Cover Dataset 1992 - Pennsylvania; Albers Grid
Edition:1
Geospatial_Data_Presentation_Form:raster digital data
Publication_Information:
Publication_Place:Sioux Falls, SD USA
Publisher:U.S. Geological Survey
Online_Linkage: http://www.pasda.psu.edu/
Description:
Abstract:
These data can be used in a geographic information system (GIS) for any
number of purposes such as assessing wildlife habitat, water quality,
pesticide runoff, land use change, etc.  The State data sets are provided
with a 300 meter buffer beyond the State border to faciliate combining
the State files into larger regions.

The user must have a firm understanding of how the datasets were compiled
and the resulting limitations of these data.  The National Land Cover Dataset
was compiled from Landsat satellite TM imagery (circa 1992) with a spatial
resolution of 30 meters and supplemented by various ancillary data (where
available). The analysis and interpretation of the satellite imagery was
conducted using very large, sometimes multi-state image mosaics (i.e. up to 18
Landsat scenes). Using a relatively small number of aerial photographs for
'ground truth', the thematic interpretations were necessarily conducted from a
spatially-broad perspective.  Furthermore, the accuracy assessments (see below)
correspond to 'federal regions' which are groupings of contiguous states.  Thus,
the reliability of the data is greatest at the state or multi-state level. The
statistical accuracy of the data is known only for the region.

Important Caution Advisory

With this in mind, users are cautioned to carefully scrutinize the data to
see if they are of sufficient reliability before attempting to use the
dataset for larger-scale or local analyses.  This evaluation must be made
remembering that the NLCD represents conditions in the early 1990s.

The Pennsylvania portion of the NLCD was created as part of land cover
mapping activities for Federal Region III that includes the States of
Maryland, Delaware, Pennsylvania, Virginia, West Virginia, and the
District of Columbia.  The NLCD classification contains 21 different
land cover categories with a spatial resolution of 30 meters.  The NLCD
was produced as a cooperative effort between the U.S. Geological Survey
(USGS) and the U.S. Environmental Protection Agency (US EPA) to produce
a consistent, land cover data layer for the conterminous U.S. using
early 1990s Landsat thematic mapper (TM) data purchased by the
Multi-resolution Land Characterization (MRLC) Consortium.  The MRLC
Consortium is a partnership of federal agencies that produce or use land
cover data.  Partners include the USGS (National Mapping, Biological
Resources, and Water Resources Divisions), US EPA, the U.S. Forest Service,
and the National Oceanic and Atmospheric Administration.
Purpose:
The main objective of this project was to generate a generalized and nationally consistent land cover data layer for the entire conterminous United States. These data can be used as a layer in a geographic information system (GIS) for any number of purposes such assessing wildlife habitat, water quality and pesticide runoff, land use change, etc.
Supplemental_Information:
The land cover data files are provided as a 'Geo-TIFF'.  The land cover
data sets are single band raster images.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date:1986
Ending_Date:1993
Currentness_Reference:
ground condition
Status:
Progress:Complete
Maintenance_and_Update_Frequency:As needed
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate:-80.438
East_Bounding_Coordinate:-75.083
North_Bounding_Coordinate:42.722
South_Bounding_Coordinate:38.912
Keywords:
Theme:
Theme_Keyword_Thesaurus:ISO 19115 Topic Categories
Theme_Keyword:Land Use/Land Cover
Theme_Keyword:Land Management
Theme_Keyword:Land Resources
Theme_Keyword:EDC
Theme_Keyword:EPA
Theme_Keyword:EROS
Theme_Keyword:Imagery
Theme_Keyword:Land Characterization
Theme_Keyword:Land Cover
Theme_Keyword:Landsat
Theme_Keyword:MRLC
Theme_Keyword:Remote Sensing
Theme_Keyword:Satellite
Theme_Keyword:Space Imaging
Theme_Keyword:USGS
Theme_Keyword:Imagery/Base Maps/Earth Cover
Place:
Place_Keyword_Thesaurus: U.S. Department of Commerce, 1977, Countries, dependencies, areas of special sovereignty, and their principal administrative divisions (Federal Information Processing Standard 10-3):Washington, D.C., National Institute of Standards and Technology.
Place_Keyword:North America
Place_Keyword:United States of America
Place:
Place_Keyword_Thesaurus: U.S. Department of Commerce, 1987, Codes for the identification of the States, the District of Columbia, and the outlying areas of the United States and associated areas Federal Information Processing Standard 5-20; Washington, D.C., National Institute of Standards and Technology.
Place_Keyword:Pennsylvania
Place_Keyword:PA
Access_Constraints:None.
Use_Constraints:
None. Acknowledgement of the U.S. Geological Survey would be
appreciated in products derived from these data.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey EROS Data Center
Contact_Position:Customer Services Representative
Contact_Address:
Address_Type:mailing and physical address
Address:
U.S. Geological Survey, EROS Data Center
City:Sioux Falls
State_or_Province:SD
Postal_Code:57198
Country:USA
Contact_Voice_Telephone:(605) 594-6151
Contact_TDD/TTY_Telephone:(605) 594-6933
Contact_Facsimile_Telephone:(605) 594-6589
Contact_Electronic_Mail_Address:CUSTSERV@EDCMAIL.CR.USGS.GOV
Data_Set_Credit:
This work was performed by the Raytheon STX Corporation under
U.S. Geological Survey Contract 1434-92-C-40004.
Native_Data_Set_Environment:
Windows NT Version 4.0 (Build 1381) Service Pack 4; ESRI ArcInfo 8.0.345
Back to Top
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
An accuracy assessment is done on all NLCD on a Federal Region basis
following a revision cycle that incorporates feedback from MRLC
Consortium partners and affiliated users.  The accuracy assessments
are conducted by private sector vendors under contract to the USEPA.
A protocol has been established by the USGS and USEPA that incorporates
a two-stage, geographically stratified cluster sampling plan (Zhu et
al., 1999)utilizing National Aerial Photography Program (NAPP)
photographs as the sampling frame and the basic sampling unit.  In
this design a NAPP photograph is defined as a 1st stage or primary
sampling unit (PSU), and a sampled pixel within each PSU is treated
as a 2nd stage or secondary sampling unit (SSU).

PSU's are selected from a sampling grid based on NAPP flight-lines and
photo centers, each grid cell measures 15' X 15' (minutes of
latitude/longitude) and consists of 32 NHAP photographs.  A geographically
stratified random sampling is performed with 1 NAPP photo being randomly
selected from each cell (geographic strata), if a sampled photo falls
outside of the regional boundary it is not used.  Second stage sampling
is accomplished by selecting SSU's (pixels) within each PSU (NAPP photo)
to provide the actual locations for the reference land cover
classification.

The SSU's are manually interpreted and misclassification errors are
estimated and described using a traditional error matrix as well as a
number of other important measures including the overall proportion of
pixels correctly classified, user's and producer's accuracy's, and
omission and commission error probabilities.

At the time of CD release (Summer 2000), the accuracy assessment was not
complete.  For the Region III accuracy assessment please check the NLCD
Website: http://edcwww.usgs.gov/programs/lccp/nationallandcover.html.
The accuracy assessment numbers will be posted there around September,
2000.

While we believe that the approach taken has yielded a very good
general land cover classification product for Region III,
it is important to indicate to the user where there might be some
potential problems. The biggest concerns for Region III are listed below:

1) Accurate definition of the transitional barren class was extremely
difficult.  The majority of pixels in this class correspond to clear-cut
forests in various stages of regrowth.  Spectrally, fresh clear-cuts are
very similar to row-crops in the leaves-off data.  Manual correction of
coding errors was performed to improve differentiation between row-crops
and clear-cuts, but some errors may still be found.  As regrowth occurs
in a clear-cut region, the definition of transitional barren versus a
forested class becomes problematic.  An attempt was made to classify only
fresh clear-cuts or those in the earliest stages of regrowth, but there
are likely forested regions classed as transitional barren and vice versa.

2) Due to the confusion between clear-cuts, regrowth in clear-cuts,
Forested areas, and shrublands, no attempts were made to populate the
shrubland classes.  Any shrubland areas that exist in this area are
classed in their like forest class, i.e. deciduous shrubland is classed as
deciduous forest, etc.
Logical_Consistency_Report:
An unsupervised classification algorithm was used to classify the
mosaicked multiple leaf-off TM scenes.  Aerial photographs were
used to interpret and label classes into land cover categories and
ancillary data sources resolved the class confusion.  Further land
cover information from leaf-on TM data, NWI data, and other sources
were incorporated to refine and augment the "basic" classification.
Completeness_Report:
All photo-interpretable data are mapped.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Each Landsat Thematic Mapper image used to create the NLCD was
precision terrain-corrected using 3-arc-second digital terrain
elevation data (DTED), and georegistered using ground control
points.  This resulted in a root mean square registration error
of less than 1 pixel (30 meters).
Lineage:
Source_Information:
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
Title:
Landsat TM scene
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Publication_Information:
Publication_Place: Sioux Falls, SD 57198 USA
Publisher:EROS Data Center
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The image provides the base from which the
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
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Landsat TM scene
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Publication_Information:
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Publisher:EROS Data Center
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Publication_Date:unknown
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Landsat TM scene
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Landsat TM scene
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
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Landsat TM scene
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
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Landsat TM scene
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Publication_Information:
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Publisher:EROS Data Center
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
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Landsat TM scene
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The image provides the base from which the
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
Title:
Landsat TM scene
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Publisher:EROS Data Center
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
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Landsat TM scene
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Publisher:EROS Data Center
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
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Landsat TM scene
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Publication_Date:unknown
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Landsat TM scene
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Originator: U.S. Geological Survey EROS Data Center
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Landsat TM scene
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
Title:
Landsat TM scene
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
Title:
Landsat TM scene
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
Title:
Landsat TM scene
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Publisher:EROS Data Center
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The image provides the base from which the
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Citation_Information:
Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
Title:
Landsat TM scene
Geospatial_Data_Presentation_Form:remote sensing image
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Publisher:EROS Data Center
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Leaf On Path/Row 016/033
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
Title:
Landsat TM scene
Geospatial_Data_Presentation_Form:remote sensing image
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Publisher:EROS Data Center
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Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
Title:
Landsat TM scene
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Publisher:EROS Data Center
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Time_Period_Information:
Single_Date/Time:
Calendar_Date:19921002
Source_Currentness_Reference:
ground condition
Source_Citation_Abbreviation:
image25
Source_Contribution:
The image provides the base from which the
land cover classification is determined.
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
Title:
Landsat TM scene
Geospatial_Data_Presentation_Form:remote sensing image
Publication_Information:
Publication_Place: Sioux Falls, SD 57198 USA
Publisher:EROS Data Center
Other_Citation_Details:
Leaf On Path/Row 017/033
Type_of_Source_Media:raster digital data
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date:19921002
Source_Currentness_Reference:
ground condition
Source_Citation_Abbreviation:
image26
Source_Contribution:
The image provides the base from which the
land cover classification is determined.
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey EROS Data Center
Publication_Date:unknown
Title:
Landsat TM scene
Geospatial_Data_Presentation_Form:remote sensing image
Publication_Information:
Publication_Place: Sioux Falls, SD 57198 USA
Publisher:EROS Data Center
Other_Citation_Details:
Leaf On Path/Row 018/032
Type_of_Source_Media:raster digital data
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date:19920806
Source_Currentness_Reference:
ground condition
Source_Citation_Abbreviation:
image27
Source_Contribution:
The image provides the base from which the
land cover classification is determined.
Process_Step:
Process_Description:
Land Cover Characterization:
The project is being carried out on the basis of 10 Federal Regions
that make up the conterminous United States; each region is comprised
of multiple states; each region is processed in subregional units
that are limited to the area covered by no more than 18 Landsat TM
scenes. The general NLCD procedure is to: (1) mosaic subregional TM
scenes and classify them using an unsupervised clustering algorithm,
(2) interpret and label the clusters/classes using aerial photographs
as reference data, (3) resolve the labeling of confused clusters/classes
using the appropriate  ancillary data source(s), and (4) incorporate
land cover information from other data sets and perform manual edits to
augment and refine the "basic" classification developed above.

Two seasonally distinct TM mosaics are produced, a leaves-on version
(summer) and a leaves-off (spring/fall) version.  TM bands 3, 4, 5,
and 7 are mosaicked for both the leaves-on and leaves-off versions.
For mosaick purposes, a base scene is selected for each mosaic and
the other scenes are adjusted to mimic spectral properties of the base
scene using histogram matching in regions of spatial overlap.
Following mosaicking, either the leaves-off version or leaves-on version
Is selected to be the "base" for the land cover mapping process.  The 4
TM bands of the "base" mosaic are clustered to produce a single 100-
class image using an unsupervised clustering algorithm. Each of the
spectrally distinct clusters/classes is then assigned to one or more
Anderson level 1 and 2 land cover classes using National High Altitude
Photography program (NHAP)and National Aerial Photography program
(NAPP) aerial photographs as a reference.  Almost invariably, individual
spectral clusters/classes are confused between two or more land cover
classes.

Separation of the confused spectral clusters/classes into appropriate
NLCD class is accomplished using ancillary data layers.  Standard
ancillary data layers include: the "non-base" mosaic TM bands and 100-
class cluster image; derived TM normalized vegetation index (NDVI),
various TM band ratios, TM date bands; 3-arc second Digital Terrain
Elevation Data (DTED) and derived slope, aspect and shaded relief;
population and housing density data; USGS land use and land cover
(LUDA); and National Wetlands Inventory(NWI) data if available. Other
ancillary data sources may include soils data, unique state or regional
land cover data sets, or data from other federal programs such as the
National Gap Analysis Program (GAP) of the USGS Biological Resources
Division (BRD).  For a given confused spectral cluster/class, digital
values of the various ancillary data layers are compared to determine:
(1) which data layers are the most effective for splitting the
confused cluster/class into the appropriate NLCD class, and (2) the
appropriate layer thresholds for making the split(s).  Models are then
developed using one to several ancillary data layers to split the
confused cluster/class into the NLCD class.  For example, a population
density threshold is used to separate high-intensity residential areas
from commercial/industrial/transportation.  Or a cluster/class might be
confused between row crop and grasslands.  To split this particular
cluster/class, a TM NDVI threshold might be identified and used with an
elevation threshold in a class-splitting model to make the appropriate
NLCD class assignments.  A purely spectral example is using the
temporally opposite TM layers to discriminate confused cluster/classes
such as hay pasture vs. row crops and deciduous forests vs. evergreen
forests; simple thresholds that contrast the seasonal differences in
vegetation between leaves-on vs. leaves-off.

Not all cluster/class confusion can be successfully modeled out.
Certain classes such as urban/recreational grasses or quarries/strip
mines/gravel pits that are not spectrally unique require manual editing.
These class features are typically visually identified and then
reclassified using on-screen digitizing and recoding.  Other classes
such as wetlands require the use of specific data sets such as NWI to
provide the most accurate classification.  Areas lacking NWI data are
typically subset out and modeling is used to estimate wetlands in these
localized areas.  The final NLCD product results from the classification
(interpretation and labeling) of the 100-class "base" cluster mosaic
using both automated and manual processes, incorporating both spectral
and conditional data layers.  For a more detailed explanation please
see Vogelmann et al. 1998 and Vogelmann et al. 1998.

Discussion:

While we believe that the approach taken has yielded a very good general
land cover classification product for the nation, it is important to
indicate to the user where there might be some potential problems.  The
biggest concerns are listed below:

1) Some of the TM data sets are not temporally ideal. Leaves-off data
sets are heavily relied upon for discriminating between hay/pasture and
row crop, and also for discriminating between forest classes.  The
success of discriminating between these classes using leaves-off data
sets hinges on the time of data acquisition.  When hay/pasture areas are
non-green, they are not easily distinguishable from other agricultural
areas using remotely sensed data.  However, there is a temporal window
during which hay and pasture areas green up before most other vegetation
(excluding evergreens, which have different spectral properties); during
this window these areas are easily distinguishable from other crop
areas. The discrimination between hay/pasture and deciduous forest is
likewise optimized by selecting data in a temporal window  where
deciduous vegetation has yet to leaf out. It is difficult to acquire a
single-date of imagery (leaves-on or leaves-off) that adequately
differentiates between both deciduous/hay and pasture and hay pasture
/row crop.

2) The data sets used cover a range of years (see data sources), and
changes that have taken place across the landscape over the time period
may not have been captured.  While this is not viewed as a major problem
for most classes, it is possible that some land cover features change
more rapidly than might be expected (e.g. hay one year, row crop the
next).

3)  Wetlands classes are extremely difficult to extract from Landsat TM
spectral information alone.  The  use of ancillary information such as
National Wetlands Inventory (NWI) data is highly desirable.  We relied
on GAP, LUDA, or proximity to streams and rivers as well as spectral
data to delineate wetlands in areas without NWI data.

4) Separation of natural grass and shrub is problematic. Areas observed
on the ground to be shrub or grass are not always distinguishable
spectrally. Likewise, there was often disagreement between LUDA and GAP
on these classes.

Acknowledgments

This work was performed under contract the U.S. Geological
Survey(Contract 1434-CR-97-CN-40274).

References

More detailed information on the methodologies and techniques employed
In this work can be found in the following:

Kelly, P.M., and White, J.M., 1993. Preprocessing remotely sensed data
for efficient analysis and classification, Applications of Artificial
Intelligence 1993: Knowledge-Based Systems in Aerospace and Industry,
Proceeding of SPIE, 1993, 24-30.

Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe, 1979.
Classification of Wetlands and Deepwater Habitats of the United States,
Fish and Wildlife Service, U.S. Department of the Interior, Washington,
D.C.

Vogelmann, J.E., Sohl, T., and Howard, S.M., 1998. "Regional
Characterization of Land Cover Using Multiple Sources of Data."
Photogrammetric Engineering & Remote Sensing, Vol. 64, No. 1,
pp. 45-47.

Vogelmann, J.E., Sohl, T., Campbell, P.V., and Shaw, D.M., 1998.
"Regional Land Cover Characterization Using Landsat Thematic Mapper
Data and Ancillary Data Sources." Environmental Monitoring and
Assessment, Vol. 51, pp. 415-428.

Zhu, Z., Yang, L., Stehman, S., and Czaplewski, R., 1999. "Designing an
Accuracy Assessment for USGS Regional Land Cover Mapping Program."
(In review) Photogrametric Engineering & Remote Sensing.
Source_Used_Citation_Abbreviation:
Landsat thematic mapper (TM)
Process_Date:19990527
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey EROS Data Center
Contact_Position:Customer Services Representative
Contact_Address:
Address_Type:mailing and physical address
Address:
U.S. Geological Survey
EROS Data Center
City:Sioux Falls
State_or_Province:SD
Postal_Code:57198
Country:USA
Contact_Voice_Telephone:(605) 594 - 6551
Contact_TDD/TTY_Telephone:(605) 594 - 6933
Contact_Facsimile_Telephone:(605) 594 - 6589
Contact_Electronic_Mail_Address:CUSTSERV@EDCMAIL.CR.USGS.GOV
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Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method:raster
Raster_Object_Information:
Raster_Object_Type:Grid Cell
Row_Count:11105
Column_Count:17370
Vertical_Count:1
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Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Map_Projection_Name:Albers Conical Equal Area
Albers_Conical_Equal_Area:
Albers Conical Equal Area
Standard_Parallel:29.500000
Standard_Parallel:45.500000
Longitude_of_Central_Meridian:-96.000000
False_Easting:0.000000
False_Northing:0.000000
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method:row and column
Coordinate_Representation:
Abscissa_Resolution:30.0
Ordinate_Resolution:30.0
Planar_Distance_Units:meters
Geodetic_Model:
Horizontal_Datum_Name:North American Datum 1983
Ellipsoid_Name:Geographic Reference System 80
Semi-major_Axis:6378137
Denominator_of_Flattening_Ratio:298.257
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Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label:Band_1
Attribute:
Attribute_Label:Order_ID
Attribute:
Attribute_Label:Value
Attribute:
Attribute_Label:Count
Overview_Description:
Entity_and_Attribute_Overview:
NOTE - All classes may NOT be represented in a specific state data set.
The class number represents the digital value of the class in the data
set.

Water
11 Open Water
12 Perennial Ice/Snow

Developed
21 Low Intensity Residential
22 High Intensity Residential
23 Commercial/Industrial/Transportation

Barren
31 Bare Rock/Sand/Clay
32 Quarries/Strip Mines/Gravel Pits
33 Transitional

Vegetated; Natural Forested Upland
41 Deciduous Forest
42 Evergreen Forest
43 Mixed Forest

Shrubland
51 Shrubland

Non-natural Woody
61 Orchards/Vineyards/Other

Herbaceous Upland
71 Grasslands/Herbaceous

Herbaceous Planted/Cultivated
81 Pasture/Hay
82 Row Crops
83 Small Grains
84 Fallow
85 Urban/Recreational Grasses

Wetlands
91 Woody Wetlands
92 Emergent Herbaceous Wetlands

NLCD Land Cover Classification System Land Cover Class Definitions:

Water All areas of open water or permanent ice/snow cover.

11. Open Water - areas of open water, generally with less
than 25 percent or greater cover of water (per pixel).

12. Perennial Ice/Snow  - All areas characterized by year-long
cover of ice and/or snow.

Developed - areas characterized by high percentage (approximately
30% or greater) of constructed materials (e.g. asphalt, concrete,
buildings, etc).

21. Low Intensity Residential - Includes areas with a mixture of
constructed materials and vegetation.  Constructed materials account
for 30-80 percent of the cover. Vegetation may account for 20 to 70
percent of the cover. These areas most commonly include single-family
housing units. Population densities will be lower than in high intensity
residential areas.

22. High Intensity Residential - Includes heavily built up urban
centers where people reside in high numbers. Examples include
apartment   complexes and row houses. Vegetation accounts for less
than 20 percent of the cover.  Constructed materials account for
80-100 percent of the cover.

23. Commercial/Industrial/Transportation - Includes infrastructure
(e.g. roads, railroads, etc.) and all highways and all developed areas
not classified as High Intensity Residential.

Barren - Areas characterized by bare rock, gravel, sad, silt, clay, or
other earthen material, with little or no "green" vegetation present
regardless of its inherent ability to support life. Vegetation, if
present, is more widely spaced and scrubby than that in the
"green" vegetated categories; lichen cover may be extensive.

31. Bare Rock/Sand/Clay - Perennially barren areas of bedrock, desert,
pavement, scarps, talus, slides, volcanic material, glacial debris, and
other accumulations of earthen material.

32. Quarries/Strip Mines/Gravel Pits - Areas of extractive mining
activities with significant surface expression.

33. Transitional - Areas of sparse vegetative cover (less than 25
percent that are dynamically changing from one land cover to
another, often because of land use activities.  Examples include
forest clearcuts, a transition phase between forest and agricultural land,
the temporary clearing of vegetation, and changes due to natural causes
(e.g. fire, flood, etc.)

Forested Upland - Areas characterized by tree cover (natural or
semi-natural woody vegetation, generally greater than 6 meters tall);
Tree canopy accounts for 25-100 percent of the cover.

41. Deciduous Forest - Areas dominated by trees where 75 percent
or more of the tree species shed foliage simultaneously in response to
seasonal change.

42. Evergreen Forest -  Areas characterized by trees where 75 percent
or more of the tree species maintain their leaves all year.  Canopy is
never without green foliage.

43. Mixed Forest -  Areas dominated by trees where neither
deciduous nor evergreen species represent more than 75 percent
of the cover present.

Shrubland - Areas characterized by natural or semi-natural woody
vegetation with aerial stems, generally less than 6 meters tall
with individuals or clumps not touching to interlocking.  Both evergreen
and diciduous species of true shrubs, young trees, and trees or shrubs
that are small or stunted because of environmental conditions are
included.

51. Shrubland - Areas dominated by shrubs; shrub canopy accounts
for 25-100 percent of the cover. Shrub cover is generally greater
than 25 percent when tree cover is less than 25 percent. Shrub cover
may be less than 25 percent in cases when the cover of other life forms
(e.g. herbaceous or tree) is less than 25 percent and shrubs cover
exceeds the cover of the other life forms.

Non-natural Woody - Areas dominated by non-natural woody
vegetation; non-natural woody vegetative canopy accounts for
25-100 percent of the cover. The non-natural woody classification
is subject to the availability of sufficient ancillary data to
differentiate non-natural woody vegetation from  natural woody vegetation.

61. Orchards/Vineyards/Other - Orchards, vineyards, and other areas
planted or maintained for the production of fruits, nuts, berries, or
ornamentals.

Herbaceous Upland - Upland areas characterized by natural or
semi- natural herbaceous vegetation;  herbaceous vegetation
accounts for 75-100 percent of the cover.

71. Grasslands/Herbaceous - Areas dominated by upland grasses
and forbs.  In rare cases, herbaceous cover is less than 25 percent,
but exceeds the combined cover of the woody species present.
These areas are not subject to intensive management, but they are
often utilized for  grazing.

Planted/Cultivated - Areas characterized by herbaceous vegetation
That has been planted or is intensively managed for the production
of food, feed, or fiber; or is maintained in developed settings for
specific purposes. Herbaceous vegetation accounts for 75-100 percent
of the cover.

81. Pasture/Hay - Areas of grasses, legumes, or grass-legume mixtures
planted for livestock grazing or the production of seed or hay crops.

82. Row Crops -  Areas used for the production of crops, such
as corn, soybeans, vegetables, tobacco, and cotton.

83. Small Grains -  Areas used for the production of graminoid
crops such as wheat, barley, oats, and rice

84. Fallow - Areas used for the production of crops that are
temporarily barren or with sparse  vegetative cover as a result of
being tilled in a management practice that incorporates prescribed
alternation between cropping and tillage.

85. Urban/Recreational Grasses - Vegetation (primarily grasses) planted
in developed settings for recreation, erosion control, or aesthetic
purposes. Examples include parks, lawns, golf courses, airport grasses,
and industrial site grasses.

Wetlands - Areas where the soil or substrate is periodically saturated
with or covered with water as defined by Cowardin et al.

91. Woody Wetlands - Areas where forest or shrubland vegetation
accounts for 25-100 percent of the cover and the soil or substrate
is periodically saturated with or covered with water.

92. Emergent Herbaceous Wetlands -  Areas where perennial
herbaceous vegetation accounts for 75-100 percent of the cover
and the soil or substrate is periodically saturated with or covered
with water.
Entity_and_Attribute_Detail_Citation:
NLCD Regional Land Cover Classification System Key Rev. 07/99
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:U.S. Geological Survey, EROS Data Center
Contact_Position:Customer Services Representative
Contact_Address:
Address_Type:mailing and physical address
Address:
Sioux Falls
City:SD
State_or_Province:SD
Postal_Code:57198
Country:USA
Contact_Voice_Telephone:605-594-6551
Contact_TDD/TTY_Telephone:605-594-6933
Contact_Facsimile_Telephone:605-594-6589
Contact_Electronic_Mail_Address:custserv@edcmail.cr.usgs.gov
Resource_Description:Pennsylvania Land Cover
Distribution_Liability:
Although these data have been processed successfully on
a computer system at the USGS, no warranty expressed or
implied is made by the USGS regarding the use of the data
on any other system, nor does the act of distribution
constitute any such warranty.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name:GeoTIFF
Format_Information_Content:
GeoTIFF is a standard for storing georeference and geocoding
information in a TIFF 6.0 compliant raster file (uncompressed).
File_Decompression_Technique:No compression applied
Transfer_Size:192.8 MB
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: \\PASDAIMS\F$\cxp7\nlcd\pagrd\pagrd
Access_Instructions:
Local area network
Offline_Option:
Offline_Media:Compact Disc-Read Only Memory (CD-ROM)
Recording_Format:ISO 9660
Fees: Current prices for the GEOTIFF NLCD data sets on CD-ROM are $32.00 + $5.00 for shipping. Fees are subject to change. Call 1-888-ASK-USGS for current prices.
Ordering_Instructions:
NLCD data may be obtained in the following ways:

1.  Contacting the nearest Digital Cartographic Data Business Partner
(GeoTIFF CD-ROM products only).  A list of the Business Partners
is available at: http://mapping.usgs.gov/www/partners/bpmain.html;
2.  Calling 1-888-ASK-USGS
3.  Ordering online via the USGS Global Land Information System at:
http://edcwww.cr.usgs.gov/Webglis/
Users of the Global Land Information System should search under the
Land Cover category.
4.  Visiting and ordering online through the NLCD availability page
at: http://edcwww.cr.usgs.gov/programs/lccp/mrlcreg.html
Technical_Prerequisites:
Geo-TIFF viewing software. Some examples are ESRI's ARC/EXPLORER and USGS's DLGV32. The DLGV32 viewer is available free for download at the MidContinent Mapping Center web site (http://mcmcweb.er.usgs.gov/). Digital image processing software or geographic information system software is required to analyze or otherwise manipulate the data.
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Metadata_Reference_Information:
Metadata_Date:20000113
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:U.S. Geological Survey, EROS Data Center
Contact_Position:Customer Services Representative
Contact_Address:
Address_Type:mailing and physical address
Address:
U.S. Geological Survey
EROS Data Center
City:Sioux Falls
State_or_Province:SD
Postal_Code:57198
Country:USA
Contact_Voice_Telephone:605-594-6551
Contact_TDD/TTY_Telephone:605-594-6933
Contact_Facsimile_Telephone:605-594-6589
Contact_Electronic_Mail_Address:custserv@edcmail.cr.usgs.gov
Metadata_Standard_Name: Federal Geographic Data Committee. Content standard for digital geospatial metadata (revised June 1998). Federal Geographic Data Committee. Washington, D.C.
Metadata_Standard_Version:FGDC-STD-001-1998
Metadata_Time_Convention:local time
Metadata_Extensions:
Online_Linkage: http://www.esri.com/metadata/esriprof80.html
Profile_Name:ESRI Metadata Profile
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