Fire frequency throughout Africa

Certain satellite sensors intercept and record outbound light coming from the Earth's surface. This light can originate from cities, night-time fishing fleets in the open sea, flares from petroleum manufacturing installations, and natural and man-made fires. These fires could be "controlled burns," to purposely remove excess vegetation cover, or wildfires in forests and brushlands. In some areas of the world, people gather or cut down local growth and burn it in a central spot in a village on a regular basis. In this case, the amount of dead or living vegetation burned is rather small, but the geographic area in which this practice is performed may be large. This image shows "fire frequency" (or how often a fire is sensed by satellite over the course of a year) from 1994 to 1995. The broad, east-west swath of fire frequency in northern-central Africa is the area also known as "The Sahel" south of the Sahara Desert. During the winter, this region is extremely dry and prone to fire hazard, so not only do man-made fires associated with agriculture occur, but natural wildfires also. Notice the absence of fires in southern-central Africa, where high, year-long rainfall is experienced and lush forests reside. Scientists studying the African continent are interested in these images, because they can give an idea as to the important ecological conditions that currently exist, and assessing the short-term and long-term impact of these trends on the people who live there. To most Africans, however, fire is not necessarily a bad thing; in East Africa, farmers use fire to burn their fields in order to restrict pervasive weed growth before planting crops. Ranchers burn their fields to promote new grass growth for their grazing livestock. In the island country of Madagascar (lower-right of image), man-made fires over time have had a huge impact on the pristine ecological conditions and biodiversity there; over eighty percent of the original forests there have been destoyed by man-made fires via "slash-and-burn" agriculture or logging.

Credit: Dylan Prentiss, Department of Geography, University of California, Santa Barbara

For more info: http://www.geog.ucsb.edu/~dylan/mtpe/biosphere/topics/veg/fires.html