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Witness Trees as Indicators of Past Fire

Photo of The figure is the cover of the station publication for the Minnesota work showing the percentage of pyrophilic witness trees across most of Minnesota with photos illustrating typical fire behavior for three areas. U.S. Department of Agriculture Forest Service.The figure is the cover of the station publication for the Minnesota work showing the percentage of pyrophilic witness trees across most of Minnesota with photos illustrating typical fire behavior for three areas. U.S. Department of Agriculture Forest Service.Snapshot : In ecosystem restoration, the question “What was the forest like back then?” is often difficult to answer. Understanding and mapping forest composition before European settlement is an important basis for ecosystem restoration. To help in returning fire into ecosystems that formerly burned, scientists from the Forest Service’s Northern Research Station used “witness trees,” which are trees indicated in old land surveys to help identify areas where fire likely occurred in the past.

Principal Investigators(s) :
Thomas-Van Gundy, Melissa 
Research Location : Northeastern United States
Research Station : Northern Research Station (NRS)
Year : 2016
Highlight ID : 1097

Summary

The recognition that disturbance played a key role in determining past forest composition, structure, and patterns has spurred efforts to map fire regimes for ecosystem restoration. Forest Service scientists at the agency’s Northern Research Station classified tree species by their relationship to fire (pyrophilic or fire-adapted and pyrophobic, not fire-adapted) and applied the classification to witness trees listed in deeds and other forms of early land surveys. From this classification, a pyrophilic percentage was calculated and these percentages spatially extrapolated to form a continuous cover across large landscapes. This technique was applied to witness trees on the Monongahela National Forest, resulting in a set of maps that can be used to help return fire as a disturbance regime. Similar maps were created for the Allegheny, Finger Lakes, Green Mountain, and White Mountain national forests, the New England region, and for Minnesota. The distribution of pyrophilic witness trees has also been useful in mapping ecological units and gives support to ecological site descriptions created by the U.S. Department of Agriculture Natural Resources Conservation Service. The pyrophilic percentage is being used in Minnesota and Wisconsin to explore drivers of the regionally important tension zone line between vegetation biomes and to create an alternate version of that line.

Forest Service Partners

External Partners

 
  • U.S. Department of Agriculture Natural Resources Conservation Service

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