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Individual Highlight

Quantifying fire effects on soil

Photo of Forest Service researchers conducted experiments at Pringle Falls Experimental Forest, Oregon, to learn how soil is affected by burn severity, and how that relates to the recovery of vegetation. Forest Service researchers conducted experiments at Pringle Falls Experimental Forest, Oregon, to learn how soil is affected by burn severity, and how that relates to the recovery of vegetation. Snapshot : Severe heating alters soil microbial communities and soil chemistry, slowing recovery of vegetation.

Principal Investigators(s) :
Smith, Jane E. 
Research Location : Pringle Falls Experimental Forest; Oregon
Research Station : Pacific Northwest Research Station (PNW)
Year : 2017
Highlight ID : 1360

Summary

Environmental change and fire suppression throughout the 20th century in the Western United States have created conditions that facilitate high-intensity forest fires. When a large piece of wood lying on the ground burns, the soil beneath the log is exposed to prolonged, intense heat. This alters soil properties and kills soil microbes. The amount of large “down” wood influences the extent of extreme soil burning. In areas that contain large amounts of large downed wood from previous wildfires, the extent of severe soil-burn can be a concern. To better quantify the effects of soil heating, scientists conducted an experiment in the Pringle Falls Experimental Forest in Central Oregon. The study team led by Jane E. Smith, a botanist with the Forest Service’s Pacific Northwest Research Station, found that the composition of soil microbial communities varied with burn severity. The greatest differences were apparent in the early time-points following the fire and decreased over four years. Severely burned soils had a fewer nutrients which slowed the recovery of vegetation for at least four years. These findings provide a foundation for ongoing studies investigating the effects of soil-burn severity on tree seedling growth, soil fungi, and nutrients. Continuing this work, the scientists are investigating soil fungal-community recovery and succession using next-generation DNA sequencing. Forest managers and members of the public are concerned about the lingering environmental effect of extreme soil heating. Findings from this study were used to address public comments to Forest Plans for the Deschutes National Forest. As burned areas continue to increase across western U.S. forests, incorporating previously burned areas into management plans and understanding the temporal fuel dynamics following high-severity fire will be essential. Increased understanding of biogeochemical processes in soils following low or high burn-intensity will contribute to best management practices aimed at mitigating the potentially negative effects of large patches of high-intensity soil burning.

Forest Service Partners

External Partners

  • Deschutes National Forest
  • Kansas State University
  • Oregon State University