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Project ID: 10-1-08-5

Year: 2010

Date Started: 09/01/2010

Date Completed: 06/26/2014

Title: Development and Validation of a Moisture-Dependent Forest Floor Fire Behavior Model

Project Proposal Abstract: Although considerable effort has been invested in studying the effects of moisture on smoldering combustion of duff (Campbell et al. 1994, 1995; Frandsen 1991, 1997; Miyanishi and Johnson 2002, Rein et al. 2008), there is little understanding of its role in fire behavior in the forest floor. The inability to model duff smoldering is a major impediment to the restoration and management of fire-prone ecosystems. Our understanding of duff fire spread and consumption patterns lags, in spite of its well-recognized importance in tree mortality, emissions, soil heating, and post-burn spatial heterogeneity (McMahon 1983, Swezy and Agee 1991, Miyanishi 2001, Knapp and Keeley 2006). Current empirical models generate binary burn no-burn results based on moisture fraction, measured bulk density, mineral content, and depth (Frandsen 1997). These site specific and environmental condition specific regression models are insufficient for use in other ecosystems and especially to predict duff smoldering behavior across the forest floor. Since forest floor strata are diverse, their presence further complicates modeling; strata have different moisture contents, contain cones and woody fragments that span one or more horizons, and have thus far, been ignored as important fuel strata. Our primary objectives are to better understand the role of fuel moisture relationships on forest floor ignition, spread, intensity, and extinction. The proposed study is focused on the development, parameterization, and validation of a moisture-dependent forest floor fire behavior model that will provide a framework for our scientific investigation and understanding. This study will improve our understanding of the role moisture plays in the behavior of fires in the forest floor. More specifically, it will improve our understanding of pre-ignition drying of forest floor fuels ahead of a smoldering front and elucidate moistures role in: 1) ignition of the forest floor by natural vector, 2) the temperature and duration of smoldering combustion, and 3) the formation of spatial patterns of forest floor consumption. The mathematical model we develop will lay the foundation for more user-friendly software for forest floor fire behavior modeling. Ultimately, the scientific knowledge above is integral to understanding important fire effects: runoff and tree stress / mortality We plan to develop a forest floor fire behavior model that builds on recent advances (Holt 2008) and incorporates moisture and heat dynamics in a spatially explicit manner. We will parameterize and test the model using a series of laboratory experiments and on-going experiments from long-unburned longleaf pine forests in northern Florida (Hiers et al. JFSP 01-1-3-11). The model will be parameterized using measurements from peat and two forest duff types (mixed conifer and pine). Once the model has been parameterized, we will test the ability of the model to make predictions; specifically pre-ignition drying of duff ahead of a smoldering front in the lab, and patterns of smoldering intensity and post-burn duff consumption in the field. Due to the stochastic nature of combustion we do not expect the model to predict exact patterns, but instead statistical properties of the spatial patterns. Laboratory experiments will focus on the effects of varying moisture on: the probability of ignition of peat and duff by various vectors (i.e., wooden dowels and cones), and the temperature and residence time of smoldering combustion (i.e., time until transition to extinction).

Principal Investigator: Christopher J. Dugaw

Agency/Organization: Humboldt State University

Branch or Dept: Department of Mathematics

Other Project Collaborators




Branch or Dept

Co-Principal Investigator

John K. Hiers

Tall Timbers Research Station

Co-Principal Investigator

Morgan J. Varner III

Forest Service

PNW-AirFire Research Team

Federal Cooperator

Phillip J. van Mantgem

USGS-Geological Survey

WERC-Redwood Field Station

Federal Fiscal Representative

Cindy C. Lu

USGS-Geological Survey

WERC-Sequoia & Kings Canyon Field Station

Project Locations

Fire Science Exchange Network











Pacific Coast States


Project Deliverables

Final Report view or print

("Results presented in JFSP Final Reports may not have been peer-reviewed and should be interpreted as tentative until published in a peer-reviewed source.")

  ID Type Title
view or print go to website 3044 Journal Article Southern Journal of Applied Forestry
view or print   3510 Journal Article Canadian Journal of Forest Research
view or print go to website 3370 Journal Article Canadian Journal of Forest Research
view or print go to website 3271 Journal Article Ecological Applications
view or print go to website 302 MS Thesis Analysis of Field Data and Spatial Methods for the Parametrization of a Spatial Duff Consumption Model (W. Gill)
view or print   7501 Poster The role of cones as vectors for duff ignition.
view or print   7502 Poster Spatial and temporal variability of forest floor duff characteristics in long-unburned Pinus palust
  go to website 3768 Website Project website.
view or print   7495 Poster "Towards a mechanism for eastern deciduous forest mesophication: the role of litter drying
    7496 Poster "Towards a mechanism for eastern deciduous forest mesophication: the role of litter drying"
    7497 Invited Paper/Presentation "The role of pine cones as a vector for duff ignition"
    7498 Invited Paper/Presentation Modeling Smoldering Combustion of Forest Duff
    7499 Invited Paper/Presentation Linking Smoldering Duff Temperatures to Surface Thermal Infrared Images
    7500 Invited Paper/Presentation Ecological consequences of smoldering fires in long-unburned longleaf pine forests
    7503 Invited Paper/Presentation Ecological consequences of fire exclusion in longleaf pinelands of the southeastern US
    7504 Field Demonstration/Tour Tour for Prescribed Fire Training Center (2011) and Alachua Conservation Trust (NGO; 2011)
    7505 Field Demonstration/Tour Informal tour for scientists and managers from the University of Florida and The Nature Conservancy
view or print   6966 Conference/Symposia/Workshop Behavior and Ecological Consequences of Smoldering Fires
view or print   6967 Computer Model/Software/Algorithm Duff Smoldering Model

Supporting Documents

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