Invasive alien plants (IAPs) and their management are perceived both negatively and positively by urban residents, but these
perceptions are shaped by individuals’ socio-demographic characteristics. This was revealed by research conducted across Cape Town by
C·I·B PhD student, Luke Potgieter, C·I·B Director Dave Richardson and C·I·B Core Team Member Mirijam
Gaertner, and recently published in the Journal of Environmental Management.
Many alien plant species are introduced to urban areas to provide ecosystem services (ES), but some of these species become
naturalised and invasive, and have negative impacts on ES and human well-being. These species may nevertheless provide important ES for urban
residents. Although the ecological impacts of invasive plant species are well documented, less attention has been given to the social dimensions
that mediate responses to biological invasions, particularly in urban areas.
Potgieter and colleagues conducted online and face-to-face questionnaire-based surveys with residents across the city of Cape Town
to determine their perceptions of IAPs. The analysis showed that conflicts of interest are likely to arise when attempting to control and eradicate
IAPs - residents perceived IAPs both negatively and positively and the management of plant invasions is not perceived as a high priority relative to
other environmental problems. For example, Port Jackson (Acacia saligna) was perceived as important for providing fuelwood, but also
perceived to have a negative impact on water security and native plant biodiversity.
Socio-demographic variables such as age, education, environmental awareness, and ethnicity shaped urban residents’ perceptions of
IAPs. For example, older, more educated respondents were more likely to perceive IAPs negatively, while respondents with greater environmental
awareness were more aware of the benefits provided by IAPs.
“This study improves our understanding of the way urban residents perceive IAPs and the ES and disservices they provide.
This can help mitigate associated conflicts of interest associated, facilitate prioritization and decision-making, and make stakeholder engagement
processes, collaboration and dialogue more effective” explains Luke Potgieter, lead author of the paper.
Potgieter adds “While this study highlights the need to integrate public perceptions into the planning and management of
IAPs, it also emphasises the importance of including ES assessments into the decision-making process, particularly in urban areas — an
approach that is becoming increasingly important as the demand for the sustainable provision of urban ES grows.”
Read the full paper at: Potgieter, L.J., Gaertner, M., O’Farrell, P.J. and Richardson, D.M. 2018. Perceptions of
impact: Invasive alien plants in the urban environment. Journal of Environmental Management.
For more information, contact Luke Potgieter at email@example.com
Examples of ecosystem services and disservices provided by invasive alien plants in Cape Town. (a) Fountain grass
(Pennisetum setaceum) planted in a residential garden (Photo: LJ Potgieter). (b) Bluegum (Eucalyptus sp.) providing shade for
a street vendor (Photo: LJ Potgieter). (c) An urban park wetland covered in a dense mat of Parrot’s feather (Myriophyllum aquaticum)
(Photo: LJ Potgieter). (d) A pine tree catches light and intensifies a blaze which broke out in an informal settlement (Photo: J Sullivan).
(e) A pine tree blown over during strong winds resulting in considerable infrastructural damage (Photo: Friends of Tokai Park).