Officials are preparing for a nearly 2,200-acre planned fire at Wind Cave National Park in southwest South Dakota.
The burn will keep ponderosa pine trees from encroaching on the prairie land. Grass will carry the fire.
The National Park Service says about 50 firefighters will be on hand.
The fire could take place as early as next week and will last three days. Smoke is expected to be heavy along Highway 385 and in the surrounding region. It will be located in the southwest corner of the park along the highway.
The prescribed fire program began in 1972. Parts of the park are burned in a controlled setting every year. The fire removes the buildup of dead brush that could fuel a wildfire and rejuvenates the prairie grasses.