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Individual Highlight

Wildfires in Southern Arizona are More Severe but Not Bigger

Photo of A specimen from the Pinaleño Mountains with seven fire scars between 1785 and 1863, but no scars from 1864 until the tree was killed by bark beetles in 1995. O'Connor, University of ArizonaA specimen from the Pinaleño Mountains with seven fire scars between 1785 and 1863, but no scars from 1864 until the tree was killed by bark beetles in 1995. O'Connor, University of ArizonaSnapshot : Scientists found that wildfires prior to 1880 burned about 70 percent of the landscape every 20 years. Since 1880 and the onset of fire exclusion, 70 percent of the landscape has not burned at all. In comparing the scientific data, scientists found that wildfires in southern Arizona have not increased in size but have increased in severity.

Principal Investigators(s) :
Lynch, Ann M.  
Research Location : Southern Arizona
Research Station : Rocky Mountain Research Station (RMRS)
Year : 2014
Highlight ID : 695

Summary

Are size and severity of wildfires and insect outbreaks increasing in high-elevation forests in the American Southwest Are changes in disturbance regimes attributable to natural variation, past forest management, or climate change? These are questions scientists with the Forest Service's Rocky Mountain Research Station and the University of Arizona set to find out by establishing the Pinaleño Demography Project. The primary goal of the project is to determine how forest vegetation, wildfire, insect outbreaks, humans, and climate interact by using tree-ring analysis to provide a historical context for modern wildfire events. The scientists found that historically, fires were often quite large, burning 50 percent or more of the landscape in single years. Prior to 1880, about 70 percent of the landscape burned every 20 years, or more frequently, but70 percent of the landscape has not burned at all since 1880. Modern wildfires are more severe than historical fires, compared to pre-1880 wildfires the proportion of high-severity area in burned areas is four times greater. Modern changes in fire spread and severity are attributed to accumulation of fine- and large-sized fuels over the landscape. The project area is located in the Pinaleño Mountains in southeast Arizona. The substantial elevational gradient and southern location of the Pinaleño Mountains make them an ideal location for studying disturbance interactions, serving as a "canary in the coal mine" for the effects of changing climate on the extensive conifer forests further north.

Additional Resources

Publication(external web site)

Forest Service Partners

External Partners

  • Coronado National Forest
  • Donald Falk, U.S. Fish and Wildlife Service
  • University of Arizona: Christopher D. O'Connor