Credits main content.



  • William J. Ripple and Robert L. Beschta, Oregon State University, Corvallis, OR


  • Ripple, W.J. and R.L. Beschta. Trophic cascades involving cougar, mule deer, and black oaks in Yosemite National Park. Biological Conservation, April 8, 2008.

Data and Images

  • Western U.S., May 2004 (Blue Marble: Next Generation; satellite: NASA Terra/Aqua, sensor: MODIS)
  • Yosemite Valley composite, May 28/June 4/July 6/ October 10, 2007 (Satellite: NASA Terra, sensor: ASTER)
  • California black oak at Yosemite (2) (© 2008 David Chudnov,
  • Evening primrose, deer and visitors in Yosemite (Courtesy Robert Beschta and William Ripple)
  • Cougar (California Department of Fish and Game)