Each year, clearing invasive alien plants costs South African farmers thousands. Not only do these plants threaten the productivity of veld for grazing, but they also use massive amounts of water, which puts extra strain on water resources that are already under pressure.
In 2002, a group of ecological and economic experts estimated that, by 2020, it would cost R4 000/ha to clear wattle invasions. By 2019, these costs had already added up to R10 000/ha, depending on terrain and invasion density. However, one should bear in mind that the clearing of these plants alone does not control their regrowth. The actual issues are vigorous coppicing and seed bank resilience.
What we know about wattle
Settler farmers introduced wattle in the 1800s to provide firewood and building material across Southern Africa’s veld. Although they provide a poverty buffer for thousands of rural families, they pose a threat to the very veld upon which these families rely.
After more than 25 years of tackling invasive alien plants across South Africa the Working for Water programme has learned some lessons:
- Wattle is very expensive to control, placing a large cost burden on landowners.
- Seed banks remain viable for decades and fire stimulates germination.
- Landowners and land rights holders need assistance to perform costly clearing activities, which include wages, tools, herbicides, supervision and transport.
- It is difficult to access available funding due to burdensome administrative requirements and gaps in the cash flow of state departments, which hamper follow-up operations to control regrowth.
Landowners should not wait for the state to secure the necessary funds to tackle this nationwide problem. Every hectare of mature wattle-invaded veld in many of South Africa’s strategic water source areas facilitates the loss of approximately two million litres of water per year through evapotranspiration. On hot, windy days, evapotranspiration rates from exotic evergreen trees can exceed annual rainfall replenishment.
Ecologically, these vital water source areas function as water replenishment hubs that provide important ecological infrastructure where good ground cover absorbs rainfall into the soil. This process replenishes groundwater, which finally emerges as seeps and springs that maintain wetlands and borehole levels in the long term.
Restoring invaded areas
Communal farmers and non-governmental organisations (NGOs) near Matatiele in the upper Umzimvubu catchment area of the Eastern Cape have been trying to address this challenge for the past two decades. Over the years, they have learned a few strategies that can help restore invaded areas to healthy veld after clearing.
These strategies can be applied to privately owned, commercial and communal land:
- Do not cut down a tree unless you are going to kill it and make sure you have a follow-up plan to manage the invaded area for at least ten years.
- Silver wattle (Acacia dealbata) is more difficult to control due to vigorous coppicing and reseeding compared to black wattle (Acacia mearnsii).
- Trees can be removed by harvesting them for, among other things, charcoal, firewood, poles and livestock fodder (wattle biomass protein content is over 15%, equivalent to many commercial supplements).
The income generated by these value chains could cover the overhead cost of clearing. The cost challenge here is herbicide, which can be avoided by labour-intensive manual debarking, or landowners can request assistance through the Department of Environment, Forestry and Fisheries (read more about this in the March issue of FarmBiz).
- After clearing, restoration can be achieved by reducing the opportunity for wattle to re-invade. Once the trees have been removed, this can be done by fostering the re-emergence of productive veld with strong grass basal cover, reducing the emergence of wattle seedlings.
- Together with managed overnight kraaling, cloven-hoofed animals on grazing farms can assist the recovery process by breaking up capped soil, dropping grass seeds contained in their dung to assist with the recovery of natural cover to outcompete wattle seeds, and trampling wattle seedling regrowth.
This strategy is part of a holistic management approach to regenerative agriculture, which aims to restore soil health, productivity and carbon storage. Ongoing effective management requires careful monitoring to maintain grass cover and control wattle seedling regrowth. Landowners and users need to be watchful for regrowth and pull out seedlings manually as they emerge to reduce costs at a later stage.
Using cattle for wattle control
Cattle have provided a dual solution in the Matatiele area. Through a market-driven mobile auction system, which is managed by local NGOs Conservation SA and Environmental and Rural Solutions, together with the small enterprise Meat Naturally, they are generating income for their owners from sales, while simultaneously assisting with rangeland recovery through improved collaborative management of herds and grazing areas.
Local NGOs in the Matatiele area work together with grazing associations and traditional leaders to allocate and manage rest areas each season, which include recovery sites that have been cleared of wattle. Grazing associations sign conservation agreements with support agents, local NGOs and social enterprise market agents that facilitate mobile auctions and monitor compliance in resting areas, through simple citizen science methods. These methods include transects for basal and species composition as part of compliance with conservation agreements.
As members of participating grazing associations, compliant farmers enjoy, among other things, the opportunity to purchase better breeding stock and access to husbandry support through subsidised vaccinations and dehorning.
This provides incentives to livestock farmers to collaboratively manage their communal rangelands, which supports the recovery of wattle-cleared areas (timeous trampling or resting to allow grass recovery) and reduces overgrazing of more palatable sites. This has been done in a communal tenure setting where collective governance is more challenging.
Private landowners can see rapid results by using this technique of managed grazing as they do not have to engage other farmers who use the land; they only need to be motivated to see the restoration process through.
Figure 1: Proposed restoration process for restoring veld after alien plant invasion.
It is possible for an area densely invaded by wattle to achieve a grass recovery rate of 80% over a period of three years. However, without ongoing watchful maintenance, such areas may revert to wattle stands due to the germination of dormant seeds in soil seed banks. Controlled burning of veld to stimulate germination of these seeds, followed by foliar spray treatment, can effectively reduce regrowth from seed stores.
Private and communal landowners and land rights holders, respectively, have different issues to deal with, but both face a common threat of land loss through alien plant invasion. The key to successfully managing wattle invasions is not to become overwhelmed. Pick your battles hectare by hectare and see the progress being made in a small area before tackling a bigger area.
Turn the liability into an asset. Make wattle invasions pay for their own demise by harvesting the trees for poles, charcoal, firewood, fodder, etc. Collaborate and network with other farmers who face similar challenges. Hands and hooves that are correctly deployed can do more than a funded programme if land users have a plan for restoring land in place. Good livestock management, together with the control of invasive alien plants, can restore healthy soil and productive veld. – Nicky McLeod, Environmental and Rural Solutions
For more information and references, contact the author on 082 782 6067 or send an email to email@example.com.