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26.  CHANGE DETECTION OF LEAFY SPURGE (EUPHORBIA ESULA) INFESTATIONS USING AERIAL PHOTOGRAPHY AND GEOGRAPHIC INFORMATION SYSTEMS

1G.L.Anderson, 1C.W. Prosser, 2Ralph Root, 2Raymond Kokaly, and 3S. Hager

Abstract: Leafy spurge is a troublesome weed in the northern Great Plains of the United States that herbicides and grazing management have not consistently controlled. The objectives of this study were to use remote sensing and GIS technologies to map and quantify the extent, distribution, and spatial-temporal dynamics of leafy spurge within Theodore Roosevelt National Park between 1993 and 1998. Preliminary analysis of the data indicated that spurge had doubled during the five-year period. Leafy spurge extent was estimated to be 591 ha in 1993 and 1,194 ha in 1998. Most infestations were restricted to drainage channels, creek bottoms, and river bottoms. The extent of leafy spurge increased across all aspects and slopes; however, the rate of increase was slower on south facing aspects and flatter slopes. The faster rate of increase on slopes ranging from 6 to 20 % indicate that leafy spurge is slowly moving out of the relatively flat drainage channels and butte tops unto steeper slopes. The difference in the rate of increase between north and south facing aspects combined with the slope and proximity to drainage channels indicate that water is likely the driving variable for leafy spurge establishment in the Badlands. Doubling the extent of leafy spurge in five years is impressive because the increase was accomplished under an aggressive weed management plan. Leafy spurge will only be controlled with aggressive and consistent application of IPM tools specifically chosen to meet the individual requirements of each situation.
 


1G. L. Anderson and C. W. Prosser, USDA, ARS, Northern Plains Agricultural Research Laboratory, 1500 N. Central Ave., Sidney, Montana 59270; 2Ralph Root and Raymond Kokaly, U.S. Geological Survey, Denver, CO 80225; 3S. Hager, USDI, Theodore Roosevelt National Park, P.O. Box 7, Medora, ND 58645.

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