See Controlled Burns for the history of burns on the site, proper procedures for burning, and pics of previous burns. New restorations are generally burned every year for five or more years. Mesic prairies require more frequent burning than dry prairies.
Fire is an important part of the natural ecology of a native prairie.
It changes dead plant material into ash which acts as a natural fertilizer, rich in potassium and phosphorous. Fire stimulates the growth of prairie species and inhibits the growth of woody plants and many non-native species. A spring fire blackens the soil and causes it to warm up faster. This gives the prairie a longer growing season.