An assessment of the evolution, costs and effectiveness of alien plant control operations in Kruger National Park, South Africa

Abstract

Alien plants were first recorded in 1937 in the 2 million ha Kruger National Park (KNP, a savanna protected area in South Africa), and attempts to control them began in the mid-1950s. The invasive alien plant control program expanded substantially in the late 1990s, but its overall efficacy has not been determined. We present an assessment of invasive alien plant control operations over several decades in KNP. We based our assessment on available information from a range of control programs funded from various sources, including national public works programs, KNP operational funds, and foreign donor funds. Over ZAR 350 million (~ US$ 27 million) has been spent on control interventions between 1997 and 2016. We found evidence of good progress with the control of several species, notably Opuntia stricta, Sesbania punicea, Lantana camara and several aquatic weeds, often because of effective biological control. On the other hand, we found that over one third (40%) of the funding was spent on species that have subsequently been recognised as being of lower priority, most of which were alien annual weeds. The allocation of funds to non-priority species was sometimes driven by the need to meet additional objectives (such as employment creation), or by perceptions about relative impact in the absence of documented evidence. We also found that management goals were limited to inputs (funds disbursed, employment created, and area treated) rather than to ecological outcomes, and progress was consequently not adequately monitored. At a species level, four out of 36 species were considered to be under complete control, and a further five were under substantial control. Attempts to control five annual species were all considered to be ineffective. Brian W. van Wilgen et al. / NeoBiota 35: 35-59 (2017) 36 On the basis of our findings, we recommend that more studies be done to determine impacts associated with individual invasive alien species; that the criteria used to prioritise invasive alien species be documented based on such assessments, so that management can justify a focus on priority species; and that funding be re-directed to those species that clearly pose greater threats, and for which other solutions (such as biological control) are not an option. NeoBiota

Indicators for monitoring biological invasions at a national level

“…We have started to estimate some aspects of invasion debt for South Africa (Faulkner, Robertson, Rouget, & Wilson, 2016;Rouget et al, 2016), but much more work is needed. Figure A1 (Indicator 1.3 van Wilgen, & McConnachie, 2012;van Wilgen, Fill, Govender, & Foxcroft, 2017). These have demonstrated effective (Te Beest et al, 2017), somewhat effective (Fill, Forsyth, Kritzinger-Klopper, Le Maitre, & van Wilgen, 2017), and ineffective (Kraaij, Baard, Rikhotso, Cole, & van Wilgen, 2017)…”

“…Focussing on species can be effective in reducing densities of a single species, but can simply clear the way for other species to invade (Zavaleta, Hobbs, & Mooney, 2001). And focussing on suites of co-occurring species at any given site is vital if impacts are to be managed (van Wilgen, Dyer, et al, 2011), but if pathways of introduction and spread are not also managed, management successes will be ephemeral.…”

“…These are clearly very specific context-dependent targets that require specific indicators to track progress, but at a broad scale such interventions would be captured in the indicator framework developed here.Indicators also need to be flexible enough to deal with different contexts. A major motivation for the South African Government's invasive plant control programmes is to provide employment opportunities (vanWilgen, Khan, & Marais, 2011), and therefore the number of jobs created is a core indicator. Similarly, successful interventions require institutional capacity, research, data and information management,…”

Economic Assessment and Community Management of Prosopis juliflora Invasion in Sweimeh Village, Jordan

“…Thus, effective policy and management responses are essential to address the multiple threats posed by IAS. Such responses require support from local communities, land managers and environmentalists and should take into account different ecological, social, economic and livelihood considerations [7][8][9].…”

Short Communication: Biodiversity of weeds in Ilmen State Reserve, Russia

“…Preservation of the species composition of background ecosystems is called for to implement protected areas, and in this regard there is reason for an optimistic approach (Krupnick and Knowlton 2017). However, creation of a network of protected areas does not solve the problem, and the problem of biological invasion is becoming increasingly important not only for economically exploited territories, but also for protected ones (Iacona et al 2016;Florens et al 2017;Ngugi and Neldner 2017;van Wilgen et al 2017). One of the reasons for this is that even in protected areas it is impossible to completely protect phytocenosis from human influence.…”