- African Mountains
The biodiversity community work hard to alert politicians, decision makers, land owners, farmers and other professionals about the dangers of alien invasive species (AIS), with little apparent success. This is especially true if the AIS has not reached ‘major infestation’ status, but will become costly if left unchecked. Time and time again one sees that unless there are laws requiring land-owners to eradicate alien vegetation, this problem is not tackled with enough vigour. Alien animals are even more difficult to control and/or eradicate because of their more subtle techniques of spread.
In African countries, there are many AIS control programmes, but there is nothing available regionally or at the continental level to deal with the containment and further spread of important invasive species. This means that in many African countries there are inadequate policy frameworks and a general lack of technical capacity in the deployment of AIS management actions.
But what if invasive species began to seriously affect food production and food security? We must understand that the problem of alien invasive species and food production goes further than just the problem of ‘agricultural weeds’. Alien invasive species have the potential to change ecosystems and landscapes, forests, waterways and catchments, and massively reduce the productivity of farm lands. Alien species affect crop lands as well as grazing lands, affect wildlife habitat and can even contribute to malaria endemicity by providing sugar-feeding plants for mosquito vectors. Understanding this risk could be a key to addressing alien species in a coordinated way in Africa.
A policy brief recently produced by the South African Institute of International Affairs (SAIIA) has highlighted the threat posed by AIS to crop lands and food security in African countries (Landmann, 2017). The Policy Brief mentions that the invasion of rangelands and croplands by harmful no-native species is not specifically mentioned in the new United Nations sustainability framework as a significant and emerging environmental issue, and that this omission needs attention. Equally, while the African Union Commission has sounded the alarm over rising food insecurity in Africa, it has not managed to develop tools or coherent strategies on how to address the challenges posed by invasive species in the context of risks to food security. A scan of the AU Commissions food security strategy for 2014 – 2017 shows that a major constraint to Africa’s agriculture productivity, invasive species, is ambiguously dealt with.
One of the challenges with alien species infestations is that they are very difficult to deal with, and information of their rate of spread and potential areas of invasion is needed to control these infestations. Action is needed before they become a problem. The SAIIA states that this is where Earth Observation (EO) sciences can be useful in identifying priority areas for different types of action, from the deployment of pre-emptive containment issues to actual eradication. With alien species, the most effective time for action is before they become established and widespread, hence surveillance is vital. Also of importance is to understand external AIS threats (plants or animals that have become invasive in countries with similar climatic conditions) and preventing their entry into the country, which means monitoring the cross-border spread of AIS. Typically, invasive species may become established around ports (the toad, Duttaphrynus melanostictus, spreading rapidly outwards from the port town of Toamasina in Madagascar) or pompom weed (Campuloclinium macrocephalum) in South Africa which has spread unchecked along roads and railway lines on the Highveld.
Pompom weed along a road in South Africa
The benefits of Earth Observation data
Research and earth observation data can help deal with the increasing spread of invasive species, particularly plants. Earth Observation (EO) protocols and data can help track the spread of invasive species and the changing patterns of invasive species propagation over time. EO has been recognised as a key tool for the management of interventions aimed at invasive species control through mapping and visualising invader distribution corridors, as well as areas that are at risk of being invaded in the future. Datasets are available for free (For example, Sentinel-2). The SAIIA policy brief concludes by suggesting that international programmes such as AfriGEOSS and UN-SPIDER should facilitate case studies that help improve the understanding of the ecology of invasions – and that these programmes should make full use of EO data.
1. Landmann T (2017). Invasive plants and food security in Africa: the potential of Earth Observation data. South African Institute of International Affairs, Policy Briefing 160.
2. Image of pompom weed: https://en.wikipedia.org/wiki/Eupatorium_macrocephalum