The usefulness of a standard method for classifying and mapping vegetation has been apparent to natural resource agencies for some time. The problem has been to agree on a standard in as diverse an area as vegetation in the United States. The National Wetland Inventory maps form the wetland vegetation standard, and have been a model for a terrestrial standard. The classification is performed in layers; both land forms and vegetation are used.
The National Vegetation Classification System (NVCS) was circulated for review by the Federal Geographic Data Committee. This standard has been tested by the National Biological Survey, the National Park Service, and the U. S. Fish and Wildlife Service (FWS) at various locations. It was originally proposed by UNESCO, has been adopted and updated by the Nature Conservancy, and is being used in the GAP program. Detailed information on the standard and the tests can be obtained by visiting the various sites listed below.
As of October 22, 1997 this standard was formally adopted by the Federal Geographic Data Committee as the Federal Standard for vegetative classification and data reporting. The FWS formally adopted this standard on August 26, 1998 (see Director's memo below).
Although this standard has been adopted by FWS it is not the only vegetation or land cover classification system in use in FWS. The NVCS assumes that vegetation on a piece of land is in some stage of reverting to a truly natural habitat. Many FWS lands are managed to maintain them at an artificial stage of habitat development that is useful to one or more wildlife species and the NVCS does not deal with that type of vegetation well. There is a problem too with incomplete vegetation data for some parts of the country.
Lastly the NVCS standard is also very expensive to implement if full field testing and data plots are used. The actual standard only requires classification to the formation level (for example Vegetated, tree-dominated, forest, deciduous cold-decidous, Lowland and submontane broad-leaved cold-deciduous). The classification system goes two steps farther through the Alliance and Association levels (in the same example this could be Acer rubrum-Nyssa sylvatica (wetland) Forest alliance, Acer rubrum/Nyssa sylvatica/Magnolia virginian Forest association). While most offices agree that the Alliance and Association levels are most useful on a refuge scale, that compounds the cost problem.
Because of the above issues staff in a several offices are testing other systems, in particular NatureServe's Ecological Systems which is related to the NVCS. It is possible in the future that there will be several tiers of vegetation and/or land use classification standards needed to meet various management and planning activities in FWS.
FWS does not currently have a lead person for vegetation questions; please contact Deb Green, National GIS Coordinator, with your questions and she will direct you to the appropriate person.
For additional information regarding this Web page, contact Deb Southworth Green, in the Division of Information Resources and Technology Management, at Deb_Green@fws.gov
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