Before European colonization of North America's Great Plains, spring and summer fires, triggered both by lightning and by Native Americans who used the fires to drive game, would race across the prairies, suppressing invasion from woody plants and hastening the germination of new grass seeds.
Today, the springtime fires in places such as Kansas are mostly agricultural fires. Farmers and ranchers use fire to clear last year's stubble. This image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite on April 14, 2005, shows dozens of fires (marked in red) burning in eastern Kansas.
NASA image created by Jesse Allen, Earth Observatory, using data obtained from the MODIS Rapid Response team.