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Pollution & Man's Influence on the Savanna

Savannas are grasslands found near tropical regions with limited rainfall. In many countries, the savannas are cleared by burning the plant life for farming and cattle pastures, building roadways and expanding cities. These anthropogenic, or man-made, activities release toxic compounds into the air, water and soil, destroying the savannah and the flora and fauna that depend upon that ecosystem.

  1. The Use of Plants to Monitor Pollution

    • Some plants can be used as chemical reservoirs for the analysis of air pollutants. A study published in the February 2008 issue of the "International Journal of Environment and Pollution" compared the number of lichens and byrophytes, a type of moss, to the accumulation of heavy metals deposited by air pollution in the savanna of West Africa. The authors found that metals, including chromium, copper, nickel, cobalt and lead accumulated to levels of 500 milligrams or more for each kilogram of plant material. The study cited that the amounts of heavy metals decreased and the population of plants increased farther away from the points of origination.

    Traffic Pollution in Savannas

    • Building of roadways leads to increased traffic and deposits of heavy metals in the soil from automobile exhaust. A study in the May 2005 issue of the "Journal of Biological Sciences" investigated the relationship between concentrations of heavy metals, fungi and microorganisms and the distance from highways traveling through the Nigerian Guinea savanna. The researchers analyzed three locations to monitor the levels of lead, arsenic, zinc, copper, cobalt, bromine and nickel as well as five species of fungi and Bacillus bacteria. The study found that metals in soil were increased in areas bordering roadways through the savanna, while the concentrations of fungi and bacteria decreased, due to the toxic nature of the metals. The study concluded that the fungi and bacteria may be useful as indicators of heavy metal contamination.

    Degradation of Soil

    • The amounts of rainfall have decreased over the past 40 years in Nigeria's Sudan and Guinea savannas, which have further exacerbated the already compromised soil quality of these areas due to farming and pollution. A study included in the May 2005 issue of the "Nigerian journal of Soil and Environmental Research" correlated the decrease in rainfall to soil degradation and erosion. The study promotes the use of anti-erosion techniques to minimize injurious impacts caused by farming practices and decreased rainfall.

    Burning Grasslands

    • Savannas in many parts of the world are set ablaze to clear the land for farming or by carelessness. Burning of these grasslands releases toxins into the air and soil, which compromises human and environmental health. A study in the April 1995 issue of "Global Biogeochemical Cycles" measured soil concentrations of pollutants from burning that included nitric oxide, methane, nitrous oxide and carbon dioxide. The researchers measured concentrations of these compounds ranging from two days after a fire to one year afterward in a savanna in Brazil. The study found that nitric oxide is the highest immediately after a fire and returned to normal levels after one year. Methane was found to be increased in freshly burnt soil and carbon dioxide remained at elevated levels for more than a year after a fire.

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