Mixed-severity fire

n. A fire that exhibits a wide range of fire severity as a result of underburning some patches, burning others with stand-replacing severity, and thinning the overstory in other patches.


  • Discussion


A mixed-severity fire exhibits a wide range of effects on the dominant vegetation. Some areas of a mixed-severity fire exhibit low fire severity, having experienced little damage to the overstory vegetation; other areas exhibit moderate fire severity, having experienced considerable overstory mortality but not complete replacement; and yet other areas exhibit high severity, having experienced complete overstory mortality.




An equal proportion of low-, moderate-, and high-severity burning clearly fits into the mixed-severity fire class, but there is currently no standard by which to define what mix of fire severities should be classified as a mixed-severity fire.  For further discussion, see Agee 1993, Agee 1998, DeBano and others 1998, Edmonds and others 2005, and Walstad and others 1990.


  • See Also

  • References

    • Agee, J.K. 1993.  Fire ecology of Pacific Northwest forests. Washington D.C.: Island Press.

    • Agee, J.K. 1998.  The landscape ecology of western forest fire regimes. Northwest Science. 72 (special issue): 24-34.

    • DeBano, L.F.; Neary, D.G.; Ffolliott, P.F. 1998.  Fire’s effects on ecosystems.  New York: John Wiley.

    • Edmonds, R.L.; Agee, J.K.; Gara, R.I. 2005.  Forest health and protection. Long Grove, IL: Waveland Press

    • Walstad, J.; Radosevich, S.; Sandberg, D. 1990.  Natural and prescribed fire in the Pacific Northwest.  Corvallis, OR: Oregon State University Press


  • Notes

    • Author 

      James Agee, Professor of Forest Ecology

      University of Washington