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Introduction
Biological invasions need to be appropriately managed to prevent and reduce negative environmental and socio-economic impacts (Simberloff et al. 2013). However, in most cases, the effort required to manage all invasions far exceeds the available resources. Moreover, such management options can create conflicts between stakeholder groups both directly (by taking away a desired resource) and indirectly (e.g. opposition to the release of chemicals) (Zengeya et al. 2017). Such conflicts can impede management interventions. Management must, therefore, be strategic such that (1) interventions are appropriate and sufficient to meet the goals of management and (2) management efforts are spatially and temporally consistent and coordinated.
A useful approach to strategic planning for biological invasions is to jointly consider groups of species with similar management requirements (van Wilgen et al. 2011). Grouping species for management identifies not only common goals but also common stakeholders. This allows for the simplification of decision-making processes. Such strategies require a good understanding of the target species (i.e. which species need to be managed and how), their pathways (i.e. the routes and vectors of introduction and spread) and the spatial distribution of impacts (i.e. areas containing resources that are susceptible to threats by invasions) (Visser et al. 2017). Effective management interventions should be planned in this context and should incorporate pathway-, species- and area-based approaches (Wilson et al. 2017).
This article explores strategic management planning using the family Cactaceae in South Africa as a case study. Cacti form a distinct taxonomic group that, with a few exceptions, share similar physiological traits, habitat preferences, spread pathways and negative impacts (Novoa et al. 2015b, 2016b) and, importantly, are also managed in similar ways (Walters et al. 2011). The aim of this article is to explore the process of developing a national strategic framework for a group of invasive species. This strategic planning process relies heavily on a good understanding of invasion processes specific to the target group and effective stakeholder engagement.
The history and status of Cactaceae in South Africa
Cacti are among the most widespread and dominant groups of invasive plants in South Africa (Nel et al. 2004; van Wilgen et al. 2012), with 35 species already listed as invaders under the National Environmental Management: Biodiversity Act no. 10 of 2004 (NEM:BA)....