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Project ID: 10-1-08-5

Year: 2010

Date Started: 09/01/2010

Ending Date:  04/30/2014

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

US Air Force

Eglin Air Force Base

Co-Principal Investigator

Morgan J. Varner III

Mississippi State University

Department of Forestry

Federal Cooperator

Phillip J. van Mantgem

USGS-Geological Survey

WERC-Redwood Field Station

Federal Fiscal Representative

Cindy C. Lu

USGS-Geological Survey

WERC-Western Ecological Research Center HQ

Project Locations












Pacific Coast States


Project Deliverables

There is no final report available for this project.
  ID Type Title
view or print go to website 3044 Journal Article Southern Journal of Applied Forestry
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)
  go to website 3768 Website Project website. Website is complete but will be expanded throughout the course of the project.
view or print   6966 Conference/Symposia/Workshop Behavior and Ecological Consequences of Smoldering Fires

Supporting Documents

There are no supporting documents available for this project.

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