The use of high-intensity fires did not help the fight against the “invasion” of bushes in the African savannah. Stellenbosch University reports .
The overgrowth of shrubs and small trees in the savanna is a significant environmental problem. The increase in tree cover leads to a reduction in the number of grass, which is necessary both for the nutrition of many mammals and serves as a home for many living creatures. For a long time, scientists hoped that high-intensity fires could solve this problem.
In 2010 and 2013, environmentalists set a series of fires in southern Africa and burned thousands of hectares of land. The strategy was a short-term success – the tree cover was indeed significantly reduced – but discussions immediately arose about the long-term effect of such a campaign. Now, more than 10 years later, South African scientists and their European colleagues have analyzed ground and satellite images of the territory.
It turned out that despite the initial encouraging results, the effect of reduction in the area of shrub cover did not persist after 10 years. Although there were large differences between intact savannah, high fire intensity, and low fire intensity a year after the experimental fires, they disappeared after 10 years. This suggests that differences in fire intensity did not have a long-term effect on bush growth, nor did the entire campaign. At the same time, many animals died in the fires, which caused criticism from some experts.
Even more worrying was the trend of tall tree loss. Over the past decade, the number of trees over ten meters in height has decreased by about 65% in all experimental plots, regardless of whether there were fires in the area.
The study shows how important long-term monitoring of environmental impacts is.