U.S. Geological Survey Gap Analysis Program- Land Cover Data v2.2Entry ID: USGS_GAP_Land_Cover
Abstract: This dataset combines the work of several different projects to create a seamless data set for the contiguous United States. Data from four regional Gap Analysis Projects and the LANDFIRE project were combined to make this dataset. In the northwestern United States (Idaho, Oregon, Montana, Washington and Wyoming) data in this map came from the Northwest Gap Analysis Project. In the southwestern ... United States (Colorado, Arizona, Nevada, New Mexico, and Utah) data used in this map came from the Southwest Gap Analysis Project. The data for Alabama, Florida, Georgia, Kentucky, North Carolina, South Carolina, Mississippi, Tennessee, and Virginia came from the Southeast Gap Analysis Project and the California data was generated by the updated California Gap land cover project. The Hawaii Gap Analysis project provided the data for Hawaii. In areas of the county (central U.S., Northeast, Alaska) that have not yet been covered by a regional Gap Analysis Project, data from the Landfire project was used. Similarities in the methods used by these projects made possible the combining of the data they derived into one seamless coverage. They all used multi-season satellite imagery (Landsat ETM+) from 1999-2001 in conjunction with digital elevation model (DEM) derived datasets (e.g. elevation, landform) to model natural and semi-natural vegetation. Vegetation classes were drawn from NatureServe's Ecological System Classification (Comer et al. 2003) or classes developed by the Hawaii Gap project. Additionally, all of the projects included land use classes that were employed to describe areas where natural vegetation has been altered. In many areas of the country these classes were derived from the National Land Cover Dataset (NLCD). For the majority of classes and, in most areas of the country, a decision tree classifier was used to discriminate ecological system types. In some areas of the country, more manual techniques were used to discriminate small patch systems and systems not distinguishable through topography. The data contains multiple levels of thematic detail. At the most detailed level natural vegetation is represented by NatureServe's Ecological System classification (or in Hawaii the Hawaii GAP classification). These most detailed classifications have been crosswalked to the five highest levels of the National Vegetation Classification (NVC), Class, Subclass, Formation, Division and Macrogroup. This crosswalk allows users to display and analyze the data at different levels of thematic resolution. Developed areas, or areas dominated by introduced species, timber harvest, or water are represented by other classes, collectively refered to as land use classes; these land use classes occur at each of the thematic levels.
Purpose: U.S. Geological Survey Gap Analysis Program Land Cover Data covers the continental United States, Alaska and Hawaii.
The original national coverage has been clipped to each of the 50 states, the 21 Landscape Conservation Cooperatives and 6 regions, This data may represent one of these subsets.
Data Set Citation
Dataset Originator/Creator: U.S. Geological Survey Gap Analysis Program, Anne Davidson, Spatial Ecologist
Dataset Title: U.S. Geological Survey Gap Analysis Program- Land Cover Data v2.2
Issue Identification: Version 2.2
Data Presentation Form: remote-sensing image
Start Date: 1999-01-01Stop Date: 2001-12-31
Accuracy assessments have been conducted for part of the Northwestern United States and the Southwestern United States
Logical_Consistency_Report: Not applicable for raster data
All cells within the continental United States have been assigned an Ecological System or land use Value and description. Work is ongoing to improve country wide consistency in the class assignment process.
Access Constraints None
Use Constraints The digital land cover dataset may be used for various purposes with user's discretion. Specifically, this dataset was created for regional terrestrial biodiversity assessment. These data are not intended to be used at scales larger than 1:100,000.
Data Set Progress
Role: TECHNICAL CONTACT
Email: adavidson at uidaho.edu
530 S. Asbury St., Suite 1
Province or State: ID
Postal Code: 99163
United States Geological Survey, EROS Data Center, National Elevation Dataset (1999), 30 Meter Digital Elevation Model, Elevation Values for the United States
United States Geological Survey, EROS Data Center, Multi-Resolution Land Characteristics Consortium (2001), Landsat 7, ETM+ Imagery, Landsat 7 ETM+ Imagery provided for Spring, Summer and Fall dates between 1999 and 2001
Multi-Resolution Land Characteristics Consortium (2001), National Land Cover Dataset, Vegetation and Land Cover Data
Extended Metadata Properties
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Creation and Review Dates
DIF Creation Date: 2013-10-07
Last DIF Revision Date: 2013-10-18