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Fires across the Sahel
This page contains archived content and is no longer being updated. At the time of publication, it represented the best available science. However, more recent observations and studies may have rendered some content obsolete.
Each year in March and April thousands of fires smolder in the
grasslands, scrub, and dry forests of the West African Sahel and
Soudanian woodlands. NASAs Moderate-resolution Imaging
Spectroradiometer (MODIS), flying aboard the Terra spacecraft,
captured this true-color image on March 2, 2001. Data from MODIS'
infrared detectors were used to locate areas where fires are
burning, shown by red dots. The arid grasslands of the Sahel are
to the north (top) of the image. The fan-shaped green area is
Lake Chad. To the center and south of the region, in northern
Nigeria, northern Cameroon and southern Chad, increasing annual
rainfall results in the gradually increasing tree cover and
darker appearance of the Soudanian woodlands.
The Sahel of West Africa is of great importance to regional
economies and human welfare. While water is always scarce in the
Sahel, even during the brief rainy season between June and
September, the grasslands provide high-quality grazing for
domestic livestock (cattle, sheep and goats). Thus the human
populations to the south rely on the Sahelian grasslands as
summer grazing for their herds in a landuse system known as
transhumance. In this system, large numbers of animals travel
north into the Sahel every year. The grasslands and woodlands of
the Soudanian zone are less nutritious for domestic animals, but
the higher rainfall allows more agriculture. Fire is used to
clear new agricultural land and to improve grazing potential of
the natural vegetation by removing dead grass and promoting new
growth. Many fires in the Soudanian zone are also ignited by
lightning strikes. During the long Sahelian dry season water
supplies limit cattle numbers and many herds travel south again
to winter on crop residues in the south. In so-doing they provide
much-needed fertilizer to the fields.
Fire has been used for centuries as a management tool in West
African agricultural and pastoral systems. However, increasing
human populations and food production requirements can reduce the
length of fallow periods and increase the frequency of fire
usage. In this situation, the benefits of fire as a management
tool can be outweighed by the negative impacts of fire on soil
fertility, leading to long-term declines in productivity.
Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team.