Fire Stories

Fire stories from the national parks highlight events, incidents, and the like, associated with fire and fuels management, as well as fire education, technology, partnerships, and more. Stories highlight work related to Department of the Interior initiatives as well as local and regional initiatives.

Tracked chipper moving trees.

A tracked chipper was used to move felled trees at Mount Rushmore National Memorial within the thin and chip treatment unit.

Reducing Crown Fire Potential and Mountain Pine Beetle Infestation Using Mechanical Treatments

Mount Rushmore National Memorial, South Dakota
Cohesive Strategy—Maintain and Restore Landscapes*

In February 2010, prompted by an ongoing mountain pine beetle outbreak in the central Black Hills, staff at Mount Rushmore National Memorial requested assistance from the Midwest Regional Office. The park asked the regional office to help prepare a plan to mitigate the impacts of a potential mountain pine beetle infestation and to reduce the crown fire potential at the Memorial. The plan was completed by a small group of specialists with input from memorial staff, the Black Hills National Forest, and other local stakeholders.

Mount Rushmore National Memorial has an extensive ponderosa pine forest, much of it old-growth, that hasn’t had a landscape-scale fire since 1893. The elimination of fire changed the historically open, heterogeneous forest structure to one that consisted primarily of closed stands with high densities of young trees. Higher tree density and ladder fuels increased the risk of stand-replacing crown fire at the Memorial. To reduce the potential for crown fire and mountain pine beetle infestation, two thinning treatments were implemented in the summer and fall of 2010. The first thin and pile treatment areas included cutting nearly all ponderosa pine trees that were six-inch diameter or less and piling the resulting material to be burned during the winter. The second treatment included cutting nearly all ponderosa pine trees that were ten-inch diameter or less and chipping the material on site. Over 500 acres, roughly 43% of the memorial, were thinned by mid to late fall 2010. National Park Service vegetation monitoring crews installed forest monitoring plots prior to this project’s implementation and revisited the same plots in the summer of 2012 to assess the effect on forest structure and to model the effectiveness of the thinning in reducing crown fire potential.

Ponderosa pine density of trees less than seven-inches in diameter decreased by an average of 78% in the thin and pile treatment unit. Ponderosa pine density of trees less than seven-inches in diameter decreased by an average of 87% in the thin and chip treatment unit.

Forested area prior to thinning treatment.
Open pine forest after thinning treatment.

Pre- (top) and post- (bottom) treatment photos from the thin and chip treatment unit at Mount Rushmore National Memorial. The top image shows the high density of small diameter trees in the understory of a pre-treatment plot in 2010. The lower image shows that small diameter tree density and ladder fuels were greatly reduced following the thin and pile treatment. NPS / Northern Great Plains I&M program

Removing most of the smaller trees greatly reduced the potential for a stand-replacing crown fire within the memorial primarily due to the significant reduction in ladder fuels. Crown fire potential was modeled pre- and post-treatment at the memorial. Initial fire behavior modeling indicated a significant reduction in crown fire as a result of the treatments.

Sixty-two percent of the memorial has now been mechanically thinned when you include areas that were treated between 2003 and 2009. In the thin and pile treatment units, piles were burned during the past two winters on approximately 185 acres of the memorial. Ultimately, it is the hope that these treatments will make the forest more resilient and resistant to infestation of mountain pine beetle, as well as expand the opportunities for fire managers to complete prescribed fire treatments at the memorial.

Contacts: Dan Swanson, Northern Great Plains Fire Ecologist

E-Mail: dan_swanson@nps.gov

Phone: (605) 745-1172

*This story supports the Department of the Interior initiatives.