Motivations and contributions of volunteer groups in the management of invasive alien plants in South Africa's Western Cape province.
Background: Research and management of biological invasions traditionally focuses on state-operated, large-scale control initiatives, with little emphasis on volunteers. Volunteering can, however, contribute to detection, extirpation and containment of invasive alien plant species (IAPS). Understanding the extent of involvement and motivations of volunteers in IAPS management is important to improve the success of invasive alien species control. Objectives: In this study we aimed to: (1) identify volunteer groups controlling IAPS in the Western Cape province of South Africa; (2) understand their practices and contributions towards detecting and controlling IAPS; (3) examine volunteer's motivations for controlling IAPS; and (4) identify the challenges individual volunteers and groups face. Methods: The data were collected using online questionnaires. Results: In total, we identified 52 volunteer groups. We broadly estimate that half of these groups that participated in the survey clear nearly 5 300 ha of land per year with estimated labour contributions of ZAR 5.1 million (equivalent to USD 0.32 million) when aligned with formal state management cost estimates. Most volunteer groups raise their own funds to facilitate their work, however, many suggest support from government entities, landowners and Non-Government Organisations would help. Most volunteers (82%) detect and report invasive species to their team leaders, citizen science platforms and relevant authorities. Volunteers themselves gain physical and psychological fulfilment and build their social capital by meeting new people. Conclusion: Our findings point to the valuable contribution of these groups, but also the need for better co-ordination and engagement between volunteer groups and mandated authorities on science, policy and management.