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Analytical Overview
Although not always detrimental, the introduction of non-native plants and animals can change the composition of grasslands and affect their capacity to sustain biodiversity. WWF-U.S. compiled non-native species data from county-level lists that document plants as native or non-native species. County-level information was then aggregated to the ecoregion level. However, the data do not distinguish between benign non-native species and aggressive species harmful to native flora and fauna. This seriously limits the usefulness of the data as an indicator of grassland condition.


Non-Native Plant Species in Grasslands in North America

Map Projection

Interrupted Goode's Homolosine

Map Description

This map shows the distribution of non-native plant species in North America grasslands. The World Wildlife Fund-US compiled data on native and non-native plant species in the United States and Canada and aggregated them to the ecoregion level (Ricketts et al. 1997). This resulting map indicates the presence of at least 10 percent non-native species in all ecoregions within the Great Plains and more than 20 percent non-native species in two ecoregions: the California Central Valley Grasslands, and the Florida Everglades. In the absence of more detailed information it is difficult to determine whether these non-native species are invasive, and spread rapidly preventing growth of native species.
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Citation:
World Resources Institute - PAGE, 2000
Sources:
  1. World Wildlife Fund. 1999, Ecoregions Database. Washington, DC:WWF-US.Unpublished database.
  2. Ricketts, T.E., Dinerstein, D. Olson, C. Loucks, W. Eichbaum, K. Kavanaugh, P. Hedao, P. Hurley, K. Carney, R. Abell, and S. Walters. 1997. A Conservation Assessment of the Terrestrial Ecoregions of North America Volume I: The United States and Canada. World Wildlife Fund - United States and World Wildlife Fund Canada.
    Prepublication Draft. 547 pp.