This is also known as prescribed burning and is often used to maintain prairie areas. This method is carefully applied in the urban area. Weather conditions must be just right and advance warning is made to people that may be affected. In the past wild fires would often burn across the prairie reducing litter and returning nutrients to the soil. The fires would be followed by fresh new growth and abundant wildflowers. Controlled burns play the same role as the wild fires from the past, they also reduce encroachment by woody species and help to control invasive non-native species.