The Extent and Effectiveness of Alien Plant Control Projects in South Africa

Abstract

Since 1995, the South African government has spent at least ZAR 15 billion (unadjusted for inflation; approximately USD1 billion) on alien plant control operations across South Africa. The amount spent per year has risen exponentially since 2010, and in 2019 annual spending is around ZAR 2 billion per year. Based on a small (but growing) number of case studies that have assessed management effectiveness, it is clear that the cover of invasive alien plants has been reduced in some localised areas, but continues to grow in others. A number of factors contribute to success, but the effort and resources required for successful control appear to be routinely underestimated , with actual costs between 1.5 and 8.6 times higher than initial budget estimates. Currently, therefore, control measures (other than biological control) have largely failed to check invasions at a national scale, and there have been no documented eradications of plant invasions from continental South Africa. We argue that control can be considerably improved by effective prioritisation, goal-setting and planning; monitoring of outcomes rather than of inputs;

Biological Invasions in South Africa: An Overview

“…Further details of the costs of invasions, and the returns on investment from control are to be found in Chaps. 15, 16, 21, and 22 (Le Maitre et al 2020;van Wilgen 2020;van Wilgen et al 2020a;Davies et al 2020).…”

“…The next charts progress with the development of a system of preventative measures and risk assessments (Kumschick et al 2020). The following chapters focus on control and rehabilitation-biological control of invasive plants (Hill et al 2020b), mechanical and chemical control of alien plants (van Wilgen et al 2020a), ecosystem restoration (Holmes et al 2020), and alien animal control (Davies et al 2020) (note: the management of aquatic plants and alien species on offshore islands are covered in Part II, together with the status of those invasions). Finally, the human dimensions affecting alien species control projects are addressed in terms of the evidence for how people cause invasions, how they conceptualise them, what effects invasive species have on people, and how people respond to them (Shackleton et al 2020, Chap.…”

Microbial Communities in the Fynbos Region of South Africa: What Happens during Woody Alien Plant Invasions

“…Alien plant invasion poses a major threat to fynbos vegetation. In 1995, the Working for Water (WfW) program introduced the combined application of mechanical removal and chemical control to remove the invasive species and promote the recovery of fynbos vegetation [8,[113][114][115] (Figure 5). The National Environmental Management: Biodiversity Act (Act 10 of 2004) promulgated actions to control alien plant invasion in fynbos to reduce the area of ecosystems under threat, and prevent the extinction of indigenous species.…”

The cost-effectiveness of water augmentation and management: Assessing the Unit Reference Value

“…The URV is thus adapted and used as a science communication tool (Blignaut et al 2010; Mander et al 2017). A decision to fund the Working for Water (WfW) programme, which was made in 1995, had a positive impact on both the livelihoods of local communities and the availability of water, and has additionally promoted advances in biological control, raised conservation awareness, enacted legislation and promoted research (Binns et al 2001;Van Wilgen & Wannenburgh 2016). The expansion of water delivery services is frustrated by a growing protest culture (Tapela 2012) and the Department of Water and Sanitation (DWS) is evaluated as being in a state of dysfunction, lacking technical personnel, institutional capacity and funding to perform maintenance on water infrastructure (Ruiters & Matji 2015).…”