Invasive alien species require co-ordinated strategic management if negative impacts are to be effectively avoided. Here we describe a strategy for the management of
Growing numbers of invasive alien species are establishing and spreading in many parts of the world, and these invasions are often accompanied by substantial negative impacts on ecosystems, the economy and human health (Pimentel
In Australia, a relatively small number of invasive alien plant species (20 in the year 2000 rising to 32 in 2014) has been designated as Weeds of National Significance (WONS, see Thorp and Lynch
Notwithstanding the challenges facing developing countries, South Africa has recently (2014) promulgated regulations (under the
In this paper, we provide a brief description of the development of a strategy and implementation plan for the management of
(a) Current distribution of
The potential distribution of
In late 2003, South Africa initiated research to investigate the potential for using biological control to combat
South Africa’s NEM:BA legislation requires that the Minister of Environmental Affairs (who is responsible for the implementation of this Act) ‘must ensure the coordination and implementation of programmes for the prevention, control or eradication of invasive species [section 75(4)]. The regulations in terms of NEM:BA, approved in October 2014, require [section 2(3)] compliance by landowners with such an Invasive Species Management Programme, where such a programme exists. During the course of 2014, workshops involving a range of stakeholders were convened to gather inputs for the development of a National Invasive Species Management Programme for
The national strategy identified five broad goals, the first of which was to establish a national invasive alien species control programme (as envisaged in NEM:BA) with adequate funding and management capacity to achieve the remaining goals. It was further recognised that a successful national programme would require cross-sectoral co-ordination and collaboration between different spheres of government and stakeholders within South Africa, and within countries bordering South Africa. The remaining four goals align with those proposed by Grice
It was explicitly recognised that the achievement of these goals would require interventions that would (a) increase awareness of the problem among stakeholders, enabling them to recognise the species in areas where it has not
occurred as yet, to appreciate the species’ potential impacts and to understand the available management options; (b) ensure that biological control is used to the fullest possible extent to reduce the impacts of
Local government in South Africa is overseen by eight metropolitan municipalities and 226 local municipalities, which together cover the whole country. We used municipal boundaries to delineate management zones, as development planning at a local level takes place within municipalities in South Africa. We used the decision tree by Grice
Allocation of management zones for the control of
A range of high-level interventions associated with each of the five broad goals of the strategy were identified, along with performance indicators that could be used to assess progress towards the goals (
Goals of the national strategy for managing
Strategic goal | Associated high-level management interventions | Proposed indicators |
---|---|---|
Establish a national invasive alien species control programme | Obtain official approval for a programme and appoint national co-ordinator |
Programme approved and co-ordinator appointed |
Prevent establishment in unoccupied areas | Identify major pathways of spread and manage to reduce risks of movement | Number of new infestations detected in previously unoccupied areas |
Detect and locally eradicate new infestations | Undertake training to raise awareness in targeted groups (e.g. agricultural extension officers) |
Number of training sessions in high-risk areas |
Contain further spread of existing infestations | Map invasions to provide a basis for developing management plans and assessing the effectiveness of management |
Area covered by populations of |
Reduce the impacts on selected assets | Identify and map selected assets |
Number of municipalities in asset protection zones with accurate maps |
The establishment of a national invasive alien species control programme for
An important component of the strategy will be to raise awareness of the problem among key stakeholders for two reasons. Firstly, in areas where the species is not yet present, people need to be made aware that it could establish there, and they need to be able to recognise the species. The strategy suggests that this awareness should be created primarily among organisations with existing invasive alien plant clearing operations and agricultural extensions officers, who could report sightings through an online reporting system (www.ispotnature.org/communities/southern-africa). Secondly, where the species is present, people need to be aware of the dangers that it poses, the ways in which spread and impact can be reduced and the methods available for control. To achieve this, educational material needs to be produced and key stakeholders need to be engaged. The intention is to develop a manual that outlines best management practices regarding the containment and control of
Biological control is seen as an indispensable aspect of the strategy. Of the 34 countries where
The potential for using remote sensing to detect and map the occurrence and distribution of
In areas where
The need for research is recognised in the strategy, and it is proposed to establish a research forum, under the auspices of the programme steering committee, to co-ordinate and review research and to foster information and technology transfer. Priority research topics that have been identified at this stage include the development of biological control solutions and remote sensing applications, the management and reduction of predicted impacts on human health and cultural issues affecting rangeland management.
Finally, engagement with international stakeholders is seen as vital. Gaining control of the existing problem in neighbouring Swaziland and Mozambique will be crucial for the achievement of long-term goals in South Africa, while prevention of spread to other neighbouring countries will require international efforts to prevent spread to new areas. With this in mind, the national steering committee will be tasked with fostering collaborative engagement with neighbouring countries.
The implementation plan has been designed to guide actions aimed at achieving the strategic goals outlined above. It sets targets that need to be achieved within a defined timeframe and serves as a framework for the allocation of funds to various projects within the national programme (
Goals, actions and targets associated with the implementation of regional management plans for the control of
Management zone | Degree of invasion by |
Management actions | Targets and timeframes |
---|---|---|---|
Prevention (low priority) | Species absent, habitat unsuitable | Reactive responses to reports of presence of weed | None |
Prevention (high priority) | Species absent, habitat suitable | Proactive surveillance |
Surveillance reports every six months |
Local eradication | Single, isolated ( > 50 km from closest neighbouring population), small (covering < 1 ha) populations | Rapid assessment of reported sightings |
Within two weeks |
Containment | Multiple populations covering > 1 ha, occurring within 50 km from each other, but localised, with > 70% of suitable habitat uninvaded | Map invasions |
Within six months of initiation of project, update annually |
Asset protection | Widespread and continuous populations covering > 30% of suitable habitat | Map invasions |
Within six months of initiation of project, update annually |
Note: Thresholds for the degree of invasion are first approximations and can be altered if needed.
Regional management plans (one each for the coastal and inland regions) will in effect be compiled ‘bottom-up’ from targets set and resources assigned to individual municipal areas. Landowners (on private land) and traditional authorities (on communal land) will be encouraged to adhere to best practice guidelines, which will be drawn up and distributed as part of the implementation of the strategy. State subsidies will be made available for the purchase and use of herbicides to control
Given that funding will almost certainly be a limiting factor, it will be necessary to prioritise interventions. Municipalities with high human population densities, well-managed rangelands and important protected areas, and municipalities that could act as source populations for further spread will be given higher priority over other areas. Sufficient funding should be allocated to priority municipalities, recognising that the alternative (dilution of funding to cover all municipalities) would lead to control efforts falling below a threshold at which the management at all of the municipalities would become ineffective. Assigning priorities and ensuring the effective use of funds will be one of the most challenging aspects of implementation.
Management plans for individual municipalities should meet minimum criteria. These include the formulation of realistic goals that can be met within specified timeframes; the effective integration of mechanical, chemical, biological and other control methods (van Wilgen
Growing infestations of
The strategy described here is yet to be implemented, and those tasked with doing so will face several challenges. A number of diverse factors contribute to the creation of these challenges, and they include ecological features of the target plant as well as the habitats that it invades, social and cultural practices that will influence management, inadequate levels of funding and multiple political considerations (
Problems and contributing factors that will lead to challenges in the implementation of a national strategy for the control of
Problem | Contributing factors | Challenge |
---|---|---|
Rapid spread of the target weed | An abundance of vectors combined with a dense network of roads and a high human population | Accurate monitoring of spread to assess effectiveness of management interventions |
Jurisdiction over management limited to South Africa | Continuous distribution of the weed across international borders | Fostering international collaboration in control efforts |
The weed readily invades overgrazed rangelands and other degraded areas | Cultural practices on communal land that place a high value on cattle, often leading to overgrazing and rangeland degradation | Reconciling differences between cultural values and rangeland management to a level that will reverse degradation |
Chemical and mechanical control is not always effective | Control methods are often not applied correctly, and there is a lack of adequate planning | Ensuring adequate planning and the consistent use of best management practices |
Multiple management goals | Projects are supported by poverty relief funds, which require a focus on employment, necessitating trade-offs between job creation and ecological goals | Maintaining a focus on priority areas for weed control, in the face of pressure to work in alternative areas that are a priority for poverty relief |
Funding is likely to be inadequate | Competing demands for scarce funding | Making effective use of limited funds through increasing efficiencies and focussing on agreed priorities |
Low levels of awareness regarding the weed | Inability to recognise the weed until it becomes well-established and ignorance of effective methods for control | Raising awareness to adequate levels in target groups |
Responsibilities under legislation are poorly understood and not enforced | Complexity of the legislation and a lack of capacity to ensure compliance | Encouraging compliance in a way that will benefit landowners and contribute to widespread control |
Insufficient collaboration between multiple arms of government, leading to poor integration of control efforts | Priorities differ between departments, leading to inadequate attention being paid to this strategy | Establishing and maintaining an effective co-ordinating committee |
Lack of capacity at municipal level | Insufficient resources and lack of expertise and capacity housed within municipal structures | Increasing knowledge and capacity at all levels within zones |
Many weed control programmes fail to set targets or to assess their progress towards targets, for a range of reasons (Denslow & D’Antonio
The above shortcomings need to be recognised and addressed by those who will be tasked with implementing this strategy. In South Africa, as elsewhere, scant attention has been paid to monitoring and evaluating the outcomes of management, for a range of reasons (van Wilgen
Possible outcomes of selected high-level indicators for assessing progress with the implementation of a national strategy to manage
Indicator | Possible outcomes | Appropriate responses |
---|---|---|
Number of new infestations detected in previously unoccupied areas | No new infestations detected |
Steps taken to reduce the risks of movement appear to be adequate, continue with these interventions |
Number of reported sightings and time taken to carry out assessments | Relatively few new sightings and/or assessments are carried out rapidly (within less than three months) |
Steps taken to carry out rapid assessments appear to be adequate, continue with these interventions |
Number of successful local eradication campaigns | Populations are successfully removed from target area |
Continue with local eradication campaigns as and where needed |
Number of containment campaigns with adequate management plans | All municipalities in containment and asset protection zones have adequate management plans |
No response required |
Effectiveness of biological control | Complete control is achieved. No other control measures are needed to reduce the weed to acceptable levels |
Chemical control can be limited to the protection of important assets |
Area covered by populations of |
Area covered decreases over time |
Steps taken appear to be effective and should be continued |
Note: The biological control outcomes are after Klein (
Outcomes for other important indicators are also uncertain and could vary from positive to negative (
Our proposed strategy is modelled in part on the Australian WONS approach (Thorpe & Lynch
There are clearly several factors that would make the implementation of control strategies for priority species more difficult to implement in developing countries, as such countries lack the resources and expertise that are available in Australia. A simple comparison between Australia and South Africa indicates several such factors. These include levels of affluence and education that will affect the relative difficulty of implementing widespread control programmes. For example, the overall and per capita GDP in 2015 was ~US$1500 billion or ~US$45 000 per person in Australia compared with ~US$366 billion or US$12 000 per person in South Africa (estimates vary according to a range of assumptions and methodologies; e.g.
South Africa, on the contrary, is relatively well off when compared with other developing nations. For example,
Financial support for the strategy was provided by the Department of Environmental Affairs-Natural Resource Management Programme. We thank the participants of the workshops, and others, for inputs into the development of this strategy, particularly Philip Blackmore, Michael Braack, Ian Macdonald, Rachel McFadyen, Ian Rushworth, John Wilson and Helmuth Zimmermann. BvW thanks the DST-NRF Centre of Excellence for Invasion Biology and the South African National Biodiversity Institute (SANBI) for funding his involvement. LS, JG and AM thank the Agricultural Research Council of South Africa for facilitating their involvement. HK and IN thank SANBI for the administration behind the strategy.
The authors declare that they have no financial or personal relationships which may have inappropriately influenced them in writing this article.
C.B. led the development of the strategy; L.S. and A.M. made inputs regarding biological control. All of the authors participated in workshops and reviewed various drafts of the strategy. B.v.W. wrote the entire paper for publication.