Cape Town - Invasive alien species are regarded as one of the top five threats to biodiversity and scientists believe a stronger approach is needed to properly manage them.
There is currently a national Working for Water programme aimed towards reducing the spread of invasive species, but in the context of South Africa other challenges are needing to be tackled simultaneously, which could slow progress.
Director of the Centre for Invasion Biology at Stellenbosch University, Professor David Richardson, said: “The Working for Water programme has made progress but despite winning some battles, the problem is getting worse.
"An issue is that the efforts to manage invaders are being carried out countrywide and the main driver of these decisions, such as where to focus and which species to focus on is dependent on job creation.”
Richardson said the management of invasive species is understandable in the context of the country's current socio-economic climate, but it was a problem when it came to getting on top of the problem.
“Managing widespread invasive species is a complex and challenging project management problem. It demands sustained dedication to each phase/step of the operation. Unplanned events such as wildfires are a huge headache to management,” he said.
Richardson said that pines in the Western Cape mountain catchment areas were getting much worse. The management of these invasions are expensive because of the inaccessibility of the terrain.
A recent survey found 1422 alien species had some serious negative impacts on South African ecosystems, such as the "thirsty" alien tree species that extract large quantities of water from catchments. There are also currently more than 18000 invasive species listed worldwide.
Richardson said: “A crucial step in overall invasive species management is to prevent invasions before they occur. Robust risk-assessment methods have been developed to form the basis of national regulations that govern the introduction of alien species. These need to be effectively applied again and this requires careful engagement with stakeholders.”
He said another crucial way in which management could become more effective was to prioritise operations better. Resources are being spread too thinly for so many invasive species and too much invaded land.
Czech Academy of Sciences Professor and Research associate at the SU Centre for Invasion Biology, Petr Pyek, said: “As our knowledge about invasive alien species increases, the problems associated with biological invasions are becoming clearer. The threats posed by invasive alien species to our environment, economies andhealth are serious, and getting worse. Policymakers and the public need to prioritise actions to stem invasions”