Black thorn is up to 9 m tall and forms almost impenetrable thicket of up to several thousand individuals per hectare. More about native bush species in Namibia
The main reasons for this are decades of overgrazing, the suppression of natural savannah fires and the prevention of natural migrations of wild animals through fences. Other causes include the increase in CO2 in the atmosphere and changes in rainfall patterns due to climate change, which promote the growth of woody species over grass.
Consequences for humans, animals and ecosystems
In areas affected by bush encroachment, wild animal populations are declining sharply, such as certain antelope species, zebras and also the cheetahs, already threatened with extinction.
That is why wildlife tourism is also severely affected, as a foundation of the Namibian tourism sector, which plays a critical role for the country's economy with a share of 15% of Namibia's gross domestic product (GDP).
Even more serious, however, is the decline in agricultural productivity caused by the displacement of grass. Rangelands degrade to wasteland with grazing animals not being able any longer to find food or to access the area affected by bush encroachment. The decline in productivity is estimated at around two-thirds in the last 40 years. Although Namibia's agricultural sector contributes only 3-5% of the country's GDP, it accounts for the by far largest share of jobs.
The bushes also take in large amounts of water from the soil via extensive root systems and evaporation through the leaves, thus greatly reducing the groundwater recharge.
Dealing with bush encroachment today
The country, where more than 70% of the population is directly or indirectly dependent on agriculture, has been suffering massively and increasingly for decades from bush encroachment in productive savannahs. Former Agriculture Minister John Mutorwa has drastically described the situation as "a national disaster situation."
In the meantime, however, bush encroachment is also an opportunity for Namibia's economic development. The bush biomass processing sector in Namibia is developing dynamically. The biomass produced by bush thinning can be processed in many ways and is already a source of income for farmers and companies. Bush wood is a raw material for firewood, animal feed, charcoal and biochar, building materials or wood-plastic composites.
In addition, there is the use of biomass for energy production. This is a central part of Namibian energy policy and is enshrined in the National Energy Policy (NEP) 2017, National Renewable Energy Policy (NREP) 2017 or National Integrated Resource Plan (NIRP) 2016. Namibia's goal is to use 70% of domestic energy sources by 2030. However, only a share of up to 80 MW or 11% has been allocated to the bush biomass, as there are considerable and more economical potentials for solar and wind energy.
Industrial companies such as Ohorongo Cement, Namibian Breweries or Rotomould Okahandja are already using bush biomass for energy purposes and new Namibian companies are also emerging to promote the approach of sustainable energy production on site. Bush biomass for energy production is also part of the strategic plan of the parastatal power generator NamPower, which is in the planning phase for a 40 MW biomass power plant near Tsumeb.
Based on studies1, Namibia currently has 412 million tonnes of usable bush biomass:
Bild: © Not published N-BiG Report to Hamburg
In 2020, 1.85 million tonnes of bush biomass is expected to be used locally (with an annual bush growth of 14 million t2) for charcoal (approx. 1 million tonnes), firewood (approx. 600,000 tonnes), fence posts (approx. 200,000 tonnes), wood chips (approx. 20,000 tonnes) and animal feed (approx. 20,000 tonnes). Including the planned power plants, a use of 3.9 million tonnes of bush biomass is forecast for 2030, with a natural re-growth of bush biomass of around 19.2 million tonnes per year by then.
This means that in Namibia, bush encroachment continues to increase - even with full exploitation of local and regional potentials. Only the export of excess bush biomass to international markets would allow to combat bush encroachment successfully.
Existing legislation determines the detailed requirements for a "sustainable bush harvest" (Policy Brief on Bush-Harvesting Guidelines 2017). The collection of bush wood is already controlled and limited: for each bush harvest, a time and geographically limited permit is issued by the Namibian Forestry Authority. In addition, advisory services, such as the De-Bushing Advisory Service, offer professional support. International markets are catered for by additional international certifications of biomass such as the Sustainable Biomass Program (SBP) and the Forest Stewardship Council (FSC).. In recent years, the latter has increased the FSC-certified area in Namibia from less than 200,000 ha to approx. 1.6 million ha.
After-care of the bush-thinned rangeland plays a central role in the harvesting and use of bush biomass, as the rootstock remaining in the soil immediately strikes out again. On the positive side, the fresh shoots can be chopped and used as animal feed. Extensive and precise handouts are already available, based on experience from the bush harvest to date, comprehensive scientific findings and a strategic Namibian environmental impact assessment.
Selective extraction of bush biomass does not cause lasting damage to the nutrient cycle if the existing basic rules are taken into account during harvesting.
1 Smit, G. N. et al (2015): Detailed Assessment of the Biomass Resource and Potential Yield in a Selected Bush Encroached Area of Namibia). Access
2 Study by N-BiG, shared by third parties such as IfaS, GIZ, NNF and others