USGS - science for a changing world

Global Ecosystems


Making this ecosystems data available to the public, other scientists, and land managers is a key goal of this activity. USGS has completed the development of terrestrial ecosystems and the associated base layers (land surface forms, surficial lithology, isobioclimates, and topographic moisture potential) for the United States, Africa, and South America. Information about both accessing and using this data is provided below.

Data Access

Pre-packaged downloadable zip files containing the various ecosystems layers for an entire country are available at: All of the ecosystems data is available as continuous raster where each pixel value represents class codes which are described in the metadata for each dataset. To assign a color for each class, a downloaded data file needs to be saved as thematic (discrete) data, and then colors can be assigned using RGB values. The RGB values of the colors used in the data viewer (and various images and publications) are also available for download.

Raster Lookup Tables (Excel): United States, Africa, South America

Terrestrial Ecosystems Metadata —
     HTML: United States, South America
     XML:   United States, South America

Topograhic Moisture Potential Metadata —
     HTML: United States
     XML:   United States

Land Surface Forms Metadata:
     HTML: United States, Africa, South America
     XML:   United States, Africa, South America

Surficial Materials Lithology Metadata —
     HTML: United States, Africa, South America
     XML:   United States, Africa, South America

Isobioclimates Metadata —
     HTML: United States, Africa, South America
     XML:   United States, Africa, South America

More detailed information about the creation of these layers is available on the appropriate "Project Areas" page.

Data Viewing and Query

The Global Ecosystems Data Viewer allows users to perform customized viewing and query of the ecosystems and base data layers.

Data Quality

This effort to map standardized, meso-scale ecosystems for both the conterminous United States and Africa is the first of its kind, and represents a biophysical stratification. The data developed for this mapping process were not all of the same quality or spatial resolution, but each dataset obtained and used for the mapping was considered to be "best available data" for that theme at a National extent. The primary goal for the first round of this mapping effort was to utilize the best source data currently available to generate a first iteration of ecosystems as quickly as possible. This goal was framed on the logic that reasonably robust and satisfactory results could be obtained from this method without a multi-year, million-plus dollar investment, and the methodology would therefore prove suitable for application in the global ecosystems mapping project under GEOSS.

As such, these data should be considered as first generation, first iteration products assembled specifically for the purpose of delineating ecosystems in a standardized manner. The input layers that represent interim products in the geospatial delineation of ecosystems should not be construed, in and of themselves, as "definitive" products. All these products could be improved in terms of strength of concept, quality of source data, and spatial resolution. These data should therefore be considered as representative of a first iteration attempt to use best available data to model standardized ecosystems, and improvements in the data input layers and final products all have the potential to be improved over time, in subsequent iterations.

Based on the nature of this first iteration of products, the following potential issues were already identified for two of the ecosystems data layers generated for the conterminous United States:
CTI in Florida Topographic Moisture Potential in Florida
Data artifact transfer from CTI source data to Topographic Moisture Potential

1) Topographic Moisture Potential - This dataset was derived from the Compound Topographic Index (CTI) dataset, which was itself a derivative product of the National Elevation Dataset (NED), created by the Elevation Derivatives for National Applications (EDNA) project. Therefore any data artifacts found in either the CTI dataset or NED were inherited in the Topographic Moisture Potential dataset. These artifacts appear as grid patterns in the Topographic Moisture Potential and can be found in areas of flatter terrain. The Topographic Moisture Potential dataset also includes small occurrences of No Data areas, with a pixel value of zero, based on No Data areas in the CTI dataset. No attempt was made to eliminate these artifacts or No Data pixels from the derived dataset; however, additional efforts are planned to research the effects of these issues.

2) Land Surface Forms - This dataset was derived from the NED based on various neighborhood analysis using a 1-km2 analysis window. However, it was determined that the NED did not include sufficient elevation data on Canadian side of the northwestern U.S.–Canada border. As a result, in the areas within approximately 600-meters to the south of this border, neighborhood analysis were run with insufficient input data therefore land surface form classes in this area are expected to have lower accuracy.

Content Accuracy, Completeness, and Usability of USGS Data and Information

We make every effort to provide and maintain accurate, complete, usable, and timely information on our Web sites. However, some USGS data and information accessed through these pages may, of necessity, be preliminary in nature and presented prior to final review and approval by the Director of the USGS. These data and information are provided with the understanding that they are not guaranteed to be correct or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user.

Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein.

Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U. S. Government.

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