The last three articles in this series have exposed the threats of invasive alien plants which act as ‘ecosystem engineers’ – decreasing soil moisture and water runoff, greatly increasing the threat of uncontrollable fires, and reducing the productivity of grazing lands, with the added danger of stock poisoning.
The last three articles in this series have exposed the threats of invasive alien plants which act as ‘ecosystem engineers’ – decreasing soil moisture and water runoff, greatly increasing the threat of uncontrollable fires, and reducing the productivity of grazing lands, with the added danger of stock poisoning.
Despite these threats, many landowners tend to respond by thinking ‘even though I am legally obliged to control aliens on my land, invasive plant clearing is just too expensive.’
But the biggest threat is yet to come – the rate of spread and cumulative impacts. Even at a conservative rate of new invasions of 5% per year, the size of the invaded area can double in 15 years.
With time and sufficient area to invade, alien species will increase in extent and density, using an even greater proportion of the available water in catchment areas.
At the national scale, the estimated reduction in surface water runoff as a result of current invasions is 43 000 million cubic metres (about 7% of the national total), mostly in fynbos and grassland areas.
If invasive alien plants spread to their full potential range, reductions would be more than eight times greater.
Decline in grazing capacity at current levels of invasion are about 1% of the potential number of livestock that can be supported, but with predicted infestation, this impact could increase to 71%.
It is absolutely crucial that all land managers carry out control measures, and to do these as effectively as possible to minimise the impact of loss of surface water runoff, groundwater recharge and livestock production.
In order to be both time and cost effective, landowners should use a strategic approach to controlling invasives on their property.
This might involve a multi-pronged approach, combining long-term initiatives (such as applying biocontrols), keeping un-invaded sites clear, and in particular, seeking advice and assistance from the Department of Water Affairs’ Albany Working for Water Project (WFW).
For long-term plans, biocontrol is an ideal control measure as it is self-sustaining, cost-effective and ecologically safe.
Over the last few years, WfW in partnership with government agencies and universities, has invested several million of rands in biocontrol research.
At present there are a number of agents available for use by landowners, but owing to the difficulties of producing insects and fungal spores, the supply chain is slow. Therefore, the sooner a landowner applies for the supply of a biocontrol, the better.
For advice on biocontrols, call Abbie Heunis on 082 809 2258. For advice and assistance with alien clearance, WfW offers a unique service.
Even if a landowner’s property does not fall within the prioritised area, and is not listed in the ‘catchment queue’, various win-win partnerships for clearing are negotiable, especially in the case of infested grazing land or wildlife farming. Possible alternatives include the provision of herbicides as required.
Once a landowner decides to enter into an agreement with WfW to clear their land, they need to apply for clearing assistance by completing a form.
This entails supplying certain details about the property, and even enables landowners to identify areas with restricted access.
WfW assists in assessing the invasive plant infestations using aerial photos and “ground truthing”. The resulting audit includes a list of invasive plants, and an assessment of their density and age classes according to vegetation blocks.
Also demarcated are those areas to be left standing (windbreaks, woodlots and shade trees). Once the application by the landowner is approved, the landowner enters into a contract with WfW.
Based on the map of vegetation blocks, a plan for clearing is generated, which is used by WfW to engage independent contractors to do the work on behalf of the land user.
Reasonable timeframes are given in which the different areas of the property will be cleared. The contractor’s teams of labourers are transported onto the site each day and the clearing operation involves an initial clear-up using methods appropriate to the type of plant (eg. resprouters are cut and poisoned).
In addition, two followup operations take place in which re-seeding and resprouting plants are eliminated. At the end of the period of about two to three years, the operations are then handed over to the landowner for their responsibility. Even at this stage, WfW is there to offer a further helping hand.
If required, a supplementary audit can be done, in which the property is mapped, showing plant species, densities and age class.
In addition, this information is analysed to determine the amount of person days per day per block required for clearing to be achieved.
This independent audit is a free service, providing a huge saving for the landowner. Landowners need to consider very carefully the repercussions of ignoring alien infestations on their land, especially given the prediction for a doubling of extent over the next 15 years.
The impacts could be disastrous. In the unpredictable climate of the Albany area, every water source is priceless. Hazardous fires are a reality.
Uncontrolled aliens will threaten livelihoods and survival. It is up to all people of the Albany area to take responsibility for the invasives on their properties and to control them.
Every invasive plant removed means fewer offspring and given the thousands of seeds produced by these plants, every plant removal counts.
It is not only a legal requirement to eradicate invasive alien plants, but an obligation to the next generation.
For further information and advice, contact Jonathan Pryor in the Albany office of the WfW programme on 046 636 1449 or 072 5078919.
