This might bore the average person because of its lack of sensationalism, but Cheatgrass has eliminated extensive amounts of wildlife by destroying the natural habitat. The range for which this grows is immense. I have heard government worker stating that this is the most destructive and detrimental factor in reducing wildlife.
http://www.invasiveplantatlas.org/wh....html?sub=5214
http://www.nytimes.com/2012/07/31/sc...oc.semityn.www