The South African government has spent R7,1 billion (adjusted to 2020 values) between 1998 and 2020 to curb the spread of invasive plants, but we are still struggling to get them under control. What we need is a national strategy that focuses on clearly defined priority sites, improves planning and monitoring, and increases operational efficiency.
This is according to a review conducted by Brian van Wilgen from the Centre for Invasion Biology at Stellenbosch University, Andrew Wannenburgh from the Department of Forestry, Fisheries and the Environment, and John Wilson from the South African National Biodiversity Institute. The findings of their study were published recently in a leading conservation science journal, Biological Conservation.
The researchers reviewed the cost, extent and effectiveness of the management of invasive plants by the government-funded Working for Water programme between 1998 and 2020 – the country’s largest intervention for managing invasive plants and for supporting a range of agencies or individuals who are legally responsible for the control of these invasive species.
For their review, they used a broad framework of indicators for assessing inputs (efforts to regulate, money spent, planning coverage and effort expended), outputs (the number of species and the extent of sites treated), and outcomes (the effectiveness of treatments in terms of changes in the extent of invasion and the recovery of biodiversity and ecosystem services) at a national level. Their study is based on
spatially explicit data on efforts that targeted selected sites and species for control; surveys of the extent of invasion; and case studies of control effectiveness.
According to the researchers, national surveys suggest that plant invasions have continued to grow in range and abundance over the past 20 years. They add that the effectiveness of control operations at roughly 76 000 sites covering 2,7 million hectares has not been monitored regularly and that only about 14% of the estimated invaded area has been tackled. More than a quarter of the control operations were not in priority areas for biodiversity and/or water conservation.
“This shows that the problem is too large to expect that invasive species can be effectively controlled everywhere in the country,” say the researchers.The full article is for subscribed members only. To view the full article please subscribe. It’s FREE!Log In Register
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