RWU NE-4153, USDA Forest Service, Northeastern Research Station, Delaware, Ohio, USA
Delaware, OH Home  Project Home  Biotrends Main  Biotrends Invasives Presentation
Last updated: January 23, 2002	Contact: Anantha Prasad

Species Invasions: (Click image to enlarge)
trends44.JPG 25.17 KB		Exotic invasions also a growing issue in this country.
trends45.JPG 68.63 KB		An estimated 6300 exotic species currently reside in this country (though it is a guess on the insects). For vertebrates and especially fishes, many of the exotics are native to some parts of the country, but have invaded other territory where they are not native. Williams JD Meffe GK. 1998. Nonindigenous species. Pages 117-129 in Mac MJ, Opler PA, Puckett Haecker CE, Doran PD. Status and trends of the nation's biological resources. U.S. Department of the Interior, U.S. Geological Survey, Reston, Va.
trends46.JPG 106.83 KB		This map shows the number of exotic plants recorded in each state. Highest exotics in CA, NY, and FL - states with a large amount of overseas traffic. Williams JD Meffe GK. 1998. Nonindigenous species. Pages 117-129 in Mac MJ, Opler PA, Puckett Haecker CE, Doran PD. Status and trends of the nation's biological resources. U.S. Department of the Interior, U.S. Geological Survey, Reston, Va.
trends47.JPG 103.16 KB		Here's the pattern for number of exotic fish recorded by state. Generally higher numbers near the coasts. Williams JD Meffe GK. 1998. Nonindigenous species. Pages 117-129 in Mac MJ, Opler PA, Puckett Haecker CE, Doran PD. Status and trends of the nation's biological resources. U.S. Department of the Interior, U.S. Geological Survey, Reston, Va.
trends48.JPG 100.66 KB		The proportion of bird numbers that are exotic breeding birds is shown here. The Midwest Corn Belt shows up clearly with up to 44% of the birds being exotic (e.g., starlings and English sparrows). http://www.fs.fed.us/pl/rpa Flather, C.H., S.J. Brady, and M.S. Knowles. 1999. Wildlife resource trends in the United States A technical document supporting the 2000 RPA Assessment. Gen. Tech. Rep. RMRS-GTR-33. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. Fort Collins, CO. 79 pp. USDA Forest Service. 2001. 2000 RPA assessment of forest and range lands. FS-687. USDA Forest Service. Washington, D.C. 78 pp.
trends49.JPG 85.41 KB		Many exotics were intentionally introduced - and for the most part, these are equally as damaging as those unintentially introduced. 60% of the terrestrial vertebrates, 40% of fishes, and 40-50% of mollusks cause harm, especially to other organisms. Williams JD Meffe GK. 1998. Nonindigenous species. Pages 117-129 in Mac MJ, Opler PA, Puckett Haecker CE, Doran PD. Status and trends of the nation's biological resources. U.S. Department of the Interior, U.S. Geological Survey, Reston, Va.
trends50.JPG 73.89 KB		The impacts of exotic species can be positive (as in the case of the honey bee for example), negative, neutral (or unknown), or both beneficial and harmful. For example, a third of exotic insects are beneficial, a third harmful, and and third neutral or unknown. A quarter of exotic terrestrial vertebrates are both beneficial and harmful, depending on spatial and temporal conditions. Seldom will we see a plant pathogen which is anything but harmful, unless it is only harmful to exotic plants. There are a few of those. Williams JD Meffe GK. 1998. Nonindigenous species. Pages 117-129 in Mac MJ, Opler PA, Puckett Haecker CE, Doran PD. Status and trends of the nation's biological resources. U.S. Department of the Interior, U.S. Geological Survey, Reston, Va.