NEWS
Bush encroachment : Making the best of a bad situation
Livestock farmers are dependent on grasslands as grazing for their animals . Yet grasslands are increasingly vulnerable to encroachment by bigger , woody plants . Preliminary results by ARC researchers indicate these woody plants may be helpful for usage in nutrient-rich animal fodder .
Julius Tjelele
For more than 60 years , research evidence showed that savannas and grasslands are altered by bush encroachment . Bush encroachment is where trees and shrubs invade grasslands and / or increase in density at the expense of grasses , forbs and herbs . The drivers for the invasion are largely man-made , due to the restriction of fires or overgrazing , for example . However , climate change contributes as well .
Bush encroachment contributes to , among others , soil erosion and a decline in forage productivity , grazing capacity and biodiversity . This has dire consequences for the growing population of the world , particularly for livestock farmers interested in grasses that provide a substantial proportion of forage for livestock production . However , there is good in every bad situation and woody plant expansion is no exception .
Although there have been numerous studies on bush encroachment , the rate and extent at which it is still increasing raises more questions . A bold statement made by Professor David Ward in a paper published in 2005 , titled “ Do we understand the causes of bush encroachment ?” is still relevant today .
There has also been a number of brush management strategies , which are aimed at improving forage quantity and quality as well as improving the economic viability of rangelands encroached by woody plants . These methods vary from mechanical to chemical and a fire-browsing combination , to the use of the encroaching woody trees and shrubs as fodder for livestock .
Using a bad situation to your advantage
The discussion around making the best of a bad situation , emanates from millions of hectares of former valuable grazing lands in South Africa being encroached by woody trees and shrubs .
This is likely to increase in the future .
Researchers from the ARC ’ s animal production , range and forage sciences department conducted studies exploring the potential use of woody or shrubby plants as fodder for livestock . It included the formulation of a diet for ruminants using bankrupt bush .
The results from ARC researcher Dr Gilbert Pule showed a relatively high crude protein content ( 7 %) in the wet season after fire ( unpublished data ). In the same study , condensed tannins were 0.1 % and 0.16 % during the dry and wet
The gist of this popular paper is how the farming community can create opportunities from bush encroachment ; how they can make the best of a bad situation .
Figure 1 : An experimental site encroached by bankrupt bush . Agricultural Research Council research shows that there may be nutritional value in some of the plants that invade rangelands that are not burnt regularly or overgrazed . Photo : Supplied / Food for Mzansi
Grassroots Vol 21 No 3 November 2021 26