Fire in Wind Cave’s future: what a vegetation model says about burning, or not burning

Without fire, ponderosa pine forest would move into the prairie of Wind Cave National Park. A vegetation model run for the park supports the park's current use of prescribed fire, and projects that fire danger will grow as the climate warms.

Fire is an important part of Black Hills ecosystems and can be controlled effectively to balance plant and animal communities. NPS photo.

Fire is an old tool

People have managed with fire for thousands of years. The Lakota used it to clear land for camps and to make hunting grounds, drawing bison and other grazers to the green grass of newly burned areas. As homesteaders moved west, use of fire dwindled because it seemed dangerous and unnatural. By the latter half of the 1900s fire had become acceptable again, as the damage from suppressing it showed up in ecosystems.

Richard Guyette and colleagues used fire scars and ring measurements on tree cross-sections to rebuild fire records from before the Industrial Revolution in the Great Plains. Fires came on average every 13 years, within a range of 4.8 to 28 or more years, and the projections of future climate in that study suggest fires could be more frequent in the northern Great Plains.

A cross section of a ponderosa from the park. Fire scars show that the tree lived through two major fires. NPS photo.

What the model does

David King and colleagues studied Wind Cave with MC1, a dynamic global vegetation model. It has three modules, for the types and mix of vegetation, for carbon, nitrogen and water cycles, and for fire occurrence, behavior and effects. A historical run for 1895–2000 gave a baseline. The future run used three climate models, all warmer: A warmer with more precipitation, B hot with no change in precipitation, and C the hottest with less precipitation and a much drier climate.

The park's location may make it more vulnerable to climate change, since it sits on an ecotone, the transition between prairie and forest. If the whole park turned to prairie, forest wildlife would lose habitat and food; if it turned to forest, grazers would lose their food.

Three futures for fire

Wildland fire crew monitoring and maintaining a prescribed burn at the Elk Mountain Campground in 2008. NPS photo.

How dangerous will it get?

Wind makes fires more severe, but MC1 cannot predict wind speeds, so the researchers used the amount of burnable fuel as a stand-in for danger. They estimated that 12 days a year in the 20th century had a lot of fuel to burn. The future run projected 20 to 100 days a year, depending on the climate model. With high winds, a large part of the forest could burn. In 2012 the Myrtle Fire burned over 10,000 acres between the park and the town of Pringle, and similar fires could become more common.

The Myrtle Fire burned over 10,000 acres between the park and the town of Pringle in 2012. NPS photo/Tom Farrell.

What it means

The data support the park's current use of prescribed fire. Because the whole park is fenced, balancing trees and prairie matters so that wildlife have enough to eat. Fire practices may need to change as the climate does, and managers should keep watching what actually happens rather than rely on MC1 alone.

Sources

• National Park Service, The Future of Fires in Wind Cave, Wind Cave National Park; discusses studies by Richard P. Guyette and others (2014) and David A. King and others (2013); rewritten in hubnx's own words.