The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite detected hundreds of fires burning across western Africa on January 04, 2014. The fires are outlined in red. Most of the fires burn in grass or cropland, which appears tan in this image. The location, widespread nature, and number of fires suggest that these fires were deliberately set to manage land.
Places where traditional plots of open land are not available because the vegetation in the area is dense are the places where "slash and burn" agriculture is practiced most often. These regions include parts of Africa, northern South America, and Southeast Asia, where an abundance of grasslands and rainforests are found.
According to About.com: "Slash and burn is a method of agriculture primarily used by tribal communities for subsistence farming (farming to survive). Humans have practiced this method for about 12,000 years, ever since the transition known as the Neolithic Revolution, the time when humans stopped hunting and gathering and started to stay put and grow crops. Today, between 200 and 500 million people, or up to 7% of the world’s population, uses slash and burn agriculture”.
Farmers often use fire to return nutrients to the soil and to clear the ground of unwanted plants. While fire helps enhance crops and grasses for pasture, the fires also produce smoke that degrades air quality. In western Africa, the agricultural burning season usually runs from January, after the year’s primary crops are harvested, through April or May, when the next growing season begins.