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Forest Disturbance Processes

Do Fire-Atmosphere Interactions Through a Pine Canopy Mediate Fire Effects During Point-Ignition Firing Operations?

[image:] Arttwork for the Eastern Area Modeling ConsortiumResearch Issue

Whether point-ignition is generated by helicopter incendiary devices or by firefighters on the ground, fire managers are cautious about using it in southeastern pine forests because of the risk of high mortality of the overstory.  The primary cause of this mortality is unknown.  Fire scientists suggestthat increases in ignition density increase the number of flame-front convergence zones, which in turn, leads to higher average fire intensities and increasing levels of tree mortality.  Other scientists suggest that a dense canopy may impede smoke and heat transport, increasing the time hot plume gases reside in the canopy volume and also broadening the plumes so that no part of the canopy remains unaffected.  The increased exposure alone may increase canopy injury or it may compound the effects of increased fire intensities.  Finally, in a recent study of a group of western conifers, researchers found that the high vapor-pressure deficits created in fire plumes are sufficient to cause embolism (a disruption of water conduction due to blockage) in branch vascular systems.  New fire-atmosphere interaction modeling and monitoring research is needed to determine the primary mechanisms by which wildland fires can lead to increasing levels of tree mortality. 

Our Research

[photo:] Observed prescribed fire in the New Jersey Pine Barrens and the typical prescribed fire conditions being examined in this study of how fire-atmosphere interactions during wildland fires can lead to tree mortality.Northern Research Station scientists in collaboration with researchers at the Pacific Northwest Research Station, Michigan State University, and the University of Idaho are exploring the dynamics of fire behavior and fire effects resulting from point-ignition patterns and testing the hypotheses outlined above.  The specific research objectives for this study include the following activities:

  • Exploring the dynamics of fire behavior and fire effects resulting from point-ignition patterns using a suite of atmospheric boundary-layer, fire behavior, and fire effects models.
  • Determining the critical parameters required for predicting canopy foliage and branch injury and tree mortality due to surface wildland fires through field experiments and modeling.

Expected Outcomes

This research will increase our understanding of how surface fires in forested environments actually cause tree mortality.  These results may aid fire and forest managers in planning the effective use of prescribed fires for fuels management so that unwanted tree mortality is minimized.  Finally, the study fulfills key research objectives for the Core Fire Science and Ecological and Environmental Fire Science portfolios of the National Wildland Fire and Fuels Research and Development Strategic Plan.

Research Participants

  • Sharon Zhong, Department of Geography, Michigan State University, East Lansing, MI
  • Michael Kiefer, Department of Geography, Michigan State University, East Lansing, MI
  • Kathleen Kavanagh, Department of Forest, Rangeland, and Fire Sciences, University of Idaho, Moscow, ID
  • Warren E. Heilman, US Forest Service, Northern Research Station, Lansing, MI
  • Joseph J. Charney, US Forest Service, Northern Research Station, Lansing, MI
  • Xindi Bian, US Forest Service, Northern Research Station, Lansing, MI
  • Matthew Dickinson, US Forest Service, Northern Research Station, Delaware, OH
  • William (Ruddy) Mell, US Forest Service, Pacific Northwest Research Station, Seattle, WA
Last Modified: August 6, 2014