5th Symposium on Fire and Forest Meteorology and the 2nd International Wildland Fire Ecology and Fire Management Congress

Monday, 17 November 2003
Potential fuel complexes, fire behavior, and fire management implications resulting from the fires of 2000 on the Bitterroot National Forest, Montana (Formerly paper 2A.7)
Tonja S. Opperman, USDA Forest Service, Bitterroot National Forest, Hamilton, MT; and T. Kelley
In western Montana, the Bitterroot Fires of 2000 burned approximately 359,000 acres across many vegetation types and under a variety of weather conditions, resulting in a mixture of fire severities, both characteristic and uncharacteristic of the historic fire regimes. The vegetative response to this disturbance is currently under study but likely will vary greatly relative to the pre-fire vegetation and the fire severity. The changing post-fire fuel complexes consisting of herbaceous, shrub and tree regeneration, and dead fuel from the previous forest stand will present significantly different fire management challenges than have been experienced in this area during the past 100 years due to the unprecedented size and location of the area impacted by uncharacteristically severe fire.

Changes to the fire management program and revision of the Forest Plan are probably necessary to accommodate the potential effects resulting from these fire events. Understanding how future fire behavior and effects are altered by seasonal timing of fires, vegetation composition (fine fuel quality), drought level, and relative amounts of standing and fallen snags will combine to dictate fuels management as well as management of inevitable future fire events.

Comparing fire intensities and fire effects on two fires on the Lewis and Clark National Forest (NF) indicates potential fuels and fire management challenges for the burned areas on the Bitterroot NF. The McDonald II Fire burned in July 2000 on the Lewis and Clark NF and, interestingly, the main carrier of the fire was not the fine herbaceous surface fuels, but rather the large dead and down (1000-hour and 10,000-hour) fuels created from a previous fire. The Biggs Flat Fire of 2001 burned in the same general area, but much later in the year, resulting in different fire behavior and effects than the McDonald II Fire. In this case, the presence of more fine fuels, large areas of tree regeneration, and significant seasonal drying effects on the large dead fuels resulted in the fire moving slowly, but burning with high intensities.

Understanding the fuels, fire behavior, and fire effects on the Lewis and Clark NF fires may aid in predicting how the future herbaceous fuel complex will develop, changes in the dead and downed woody fuel complex over time and implications for fire behavior, and when high intensity fires will return to burned areas on the Bitterroot NF. We will consider the differences in vegetation types, historic fire regimes, fire weather, and proximity to wildland-urban interface between the two forests to determine the applicability of these fire events to future fuels management in burned areas on the Bitterroot NF. Finally, we draw conclusions about how to protect values at risk from unacceptable effects of future fires on the Bitterroot NF.

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