EPOW - Ecology Picture of the Week

Each week a different image of our fascinating environment is featured, along with a brief explanation written by a professional ecologist.

21-27 May 2018

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Encroachment in the Steppe

One-seed Juniper (Juniperus monosperma), Family Cupressaceae
Wupatki National Monument, Arizona USA

Credit & Copyright: Dr. Bruce G. Marcot

Explanation:  From this most unusual vantage point we can view a landscape of native trees acting like invasive species in their own domain.  

The multitudinous green blobs are one-seed junipers, native to southwest U.S.  

The spread of juniper trees onto native grasslands and steppe is known as encroachment.  It has been recognized since at least the early 1960s (Johnsen 1962, Burkhardt and Tisdale 1976).  
  


Information:
     Burkhardt, J.W. and E.W. Tisdale.  1976.  Causes of juniper invasion in southwestern Idaho.  Ecology 57(3):472-484.
     Johnsen, T.N.  1962.  One-seed juniper invasion of northern Arizona grasslands.  Ecological Monographs 32(3):187-207.

              
    

Next week's picture:  Function and Fate of the Nurse Stump

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