USDA Forest Service

Fire and Environmental Research Applications Team


Fire and Environmental Research Applications Team
Pacific Wildland Fire Sciences Laboratory

400 N 34th Street, Suite 201
Seattle, WA 98103

(206) 732-7800

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United States Department of Agriculture Forest Service.

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Icon of magnifying glassLitter and Duff Bulk Densities in the Southern United States

Photo of forester on the ground looking at duff in GeorgiaFinishedFinal Report to the Joint Fire Science Program [.pdf]


The organic layer (litter and duff) in forest, shrub, and grasslands can represent the bulk of the fuels consumed during wildland fires in southern ecosystems; it is imperative that organic layer depth measurements can be converted to mass as managers often measure the depth of the litter and organic duff layers. In order to convert depth measurements to mass, a bulk density is required for each layer. Also, the DMM600 Duff Moisture Meter developed through collaboration between Campbell Scientific, Inc. and the USDA, Forest Service, Rocky Mountain Research Station and Missoula Technology and Development Center measures volumetric moisture of forest floor materials. These volumetric moisture contents can be converted to gravimetric moisture content if duff bulk density values are known.

Organic layer mass and duff moisture are critical variables when estimating fuel consumption and potential fire effects such as tree and shrub mortality, and smoke production during wildland fire. Some field research has been conducted to quantify organic layer bulk densities in the southeastern part of the United States, although it has generally been limited to less productive sand pine and sand hill sites at Eglin Air Force Base. The objective of this research proposal was to quantify bulk density for litter and duff layers in 6 forest, shrub, and grassland fuelbed types. The data was compiled and analyzed to provide bulk density values for use in specific vegetation types.

Related Publications

Ottmar, Roger D.; Vihnanek, Robert E..; Wright Clinton S. 2003. Stereo photo series for quantifying natural fuels in the Americas. Abstract. In: Kush, John S., comp. Longleaf pine: A southern legacy rising from the ashes, proceedings of the Fourth Longleaf Alliance Regional Conference. Longleaf Alliance Report No. 6.
Full text [.pdf]

Team Lead: Roger Ottmar

Collaborators: Tall Timbers Research Station, National Park Service, U.S. Fish and Wildlife Service

Logo of the Joint Fire Science ProgramWe acknowledge funding from the Joint Fire Science Program under Project JFSP 04-2-1-49.



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