Research shows debushing improves rangeland in four seasons
By Freeman Ya Ngulu.
According to the African Journal of Range & Forage Science latest issue published online on 15 November 2023, woody plant encroachment threatens ecosystems by reducing herbaceous plant population and cover.
In short, bush encroachment reduces the cover and volume of all the other plants in the ecosystem.
Lead researcher, Piet Monegi who specialises in Animal Production at the Agricultural Research Council at Irene near Pretoria and teaches at the Life Sciences faculty at the University of KwaZulu-Natal in Pietermaritzburg. assessed the impact of woody removal intensity on the grass ground cover, grass composition, diversity and richness, and rangeland condition in a South African savanna over a period of four growing seasons (2018–2022).
This research is particularly relevant for Namibian farmers where an estimated 45 million hectares of savannah is infested with encroacher bush, according to the Ministry of Environment, Forestry and Tourism.
“This has had a negative impact on biodiversity and the livelihoods of people, especially those local communities which are largely dependent on the country’s vast natural resources, especially our savanna ecosystem,” stated the minister, Hon Pohamba Shifeta.
He added that bush encroachment can offer vast economic opportunities from debushing, charcoal production and export, green electricity generation, and animal feed production.
“For us this is critical if it is done sustainably and based on the application of science and value addition, to ensure that such processes benefit our local communities,” Shifeta said.
The South African team’s research is corroborated by similar studies in the United States where David Ward from the Department of Biological Sciences at Kent State University in Ohio, found that selective tree removal to reduce woody density, had a measurable impact on the proliferation of other vegetation, and a visible impact on the condition of the rangeland.
Overall, results showed that moderate removal of trees (i.e. 50%) in rangelands encroached by woody plants has the potential to maximise rangeland condition and can be used as a strategy for the restoration of herbaceous vegetation to increase grazing capacity.
