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Author (up) De Stoppelaire, G.H.; Gillespie, T.W.; Brock, J.C.; Tobin, G.A. doi  openurl
  Title Use of remote sensing techniques to determine the effects of grazing on vegetation cover and dune elevation at Assateague Island National Seashore: impact of horses Type Journal Article
  Year 2004 Publication Environmental Management Abbreviated Journal Environ Manage  
  Volume 34 Issue 5 Pages 642-649  
  Keywords Animals; Animals, Wild; Conservation of Natural Resources; Ecosystem; Environmental Monitoring; *Feeding Behavior; *Horses; Maryland; Plants/*growth & development; Population Dynamics; Silicon Dioxide; *Soil  
  Abstract The effects of grazing by feral horses on vegetation and dune topography at Assateague Island National Seashore were investigated using color-infrared imagery, lidar surveys, and field measurements. Five pairs of fenced and unfenced plots (300 m2) established in 1993 on sand flats and small dunes with similar elevation, topography, and vegetation cover were used for this study. Color-infrared imagery from 1998 and field measurements from 2001 indicated that there was a significant difference in vegetation cover between the fenced and unfenced plot-pairs over the study period. Fenced plots contained a higher percentage of vegetation cover that was dominated by American beachgrass (Ammophila breviligulata). Lidar surveys from 1997, 1999, and 2000 showed that there were significant differences in elevation and topography between fenced and unfenced plot-pairs. Fenced plots were, on average, 0.63 m higher than unfenced plots, whereas unfenced plots had generally decreased in elevation after establishment in 1993. Results demonstrate that feral horse grazing has had a significant impact on dune formation and has contributed to the erosion of dunes at Assateague Island. The findings suggest that unless the size of the feral horse population is reduced, grazing will continue to foster unnaturally high rates of dune erosion into the future. In order to maintain the natural processes that historically occurred on barrier islands, much larger fenced exclosures would be required to prevent horse grazing.  
  Address US Geological Survey, Center for Coastal and Watershed Studies, St. Petersburg, Florida 33701, USA. georgia.destoppelaire@my.FWC.com  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0364-152X ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15633024 Approved no  
  Call Number Serial 1896  
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