Perceptions of impact: Invasive alien plants in the urban environment

Abstract

Many alien plant species are introduced to urban areas to create, augment or restore ecosystem services (ES). However, many of these species spread beyond original plantings, sometimes causing negative effects on existing ES or creating novel ecosystem disservices (EDS). An understanding of the perceptions of urban residents regarding invasive alien plants (IAPs) and the ES and EDS they provide is needed for the effective prioritisation of IAP management efforts in cities. Using the city of Cape Town, South Africa as a case study, we conducted questionnaire-based surveys (online and face-to-face) to determine the perceptions of urban residents regarding IAPs and their capacity to provide ES and EDS. Most urban residents perceive IAPs negatively (i.e. agreeing that they create EDS), but many recognise their importance in providing ES. Although most residents are not opposed to the management of IAPs, such actions are not perceived as a high priority relative to other environmental problems. Socio-demographic variables such as age, education, environmental awareness, and ethnicity shape urban residents' perceptions of IAPs. Older, more educated respondents were more likely to perceive IAPs negatively, while respondents with greater environmental awareness were aware of the benefits provided by IAPs. This study highlights the need to integrate public perceptions into the planning and management of IAPs and emphasises the importance of including ES assessments into the decision-making process, particularly in urban areas.

Invasive alien plant species: Their impact on environment, ecosystem services and human health

“…In this section we describe the environmental and ecosystem services, taking urban environment as classical example of invasion. In fragmented urban ecosystems, there is an urgent need to document the beneficial environmental/ecological services (Potgieter et al, 2017;Potgieter et al, 2019). Further, the uneven and unequal diversion of economic funds for urban and city planning can also limit the management aspects of the urban vegetation (Irlich et al, 2017).…”

“…Further, the uneven and unequal diversion of economic funds for urban and city planning can also limit the management aspects of the urban vegetation (Irlich et al, 2017). Urban environment can be ideal model system for plant invasions as they face the problem of habitat fragmentation, shift in land use, climate change, resources as well as hydraulic alterations and pollution and geological disturbance which are congenial to the IAPS colonization and spread (Klotz and Kühn, 2010;Cadotte et al 2017;Potgieter et al, 2017Potgieter et al, 2019.…”

“…can be considered (Costanza et al, 2007;Potgieter et al, 2017). Acer platanoides, the most widely recorded global IAPS, removes CO 2 and thus contributes to climate change mitigation, but it also contributes to the emission of biogenic volatile organic compounds (BVOCs) (Millward and Sabir, 2011;Bogacki and Syguła, 2013;Potgieter et al, 2017;Potgieter et al, 2019). IAPS drastically alter soil attributes, however, certain IAPS like Kudzu (Pueraria montana), have been found to have potential to reduce soil erosion (Forseth and Innis, 2004).…”

Biological Invasions in South Africa’s Urban Ecosystems: Patterns, Processes, Impacts, and Management

“…15;Zengeya et al 2020, Chap. 17) and creating a novel suite of EDS such as increased safety and security risks (Potgieter et al 2018(Potgieter et al , 2019b; Supplementary Appendix 11.1).…”

A fine-scale assessment of the ecosystem service-disservice dichotomy in the context of urban ecosystems affected by alien plant invasions

“…For example, Acacia saligna which was introduced to stabilise shifting sands has spread far beyond sites of formal plantings; it now negatively impacts biodiversity, surface water runoff, and exacerbates wildfires (van Wilgen and Richardson 1985;Le Maitre et al 2002;Yelenik et al 2004Yelenik et al , 2007. However, despite the negative impacts of IAPs, some species remain beneficial to many urban residents (Gaertner et al 2016;Potgieter et al 2019b) namely through recreation, shade and visual amenity. This situation provides a unique opportunity to examine the applicability of remote sensing techniques for the spatially-explicit assessment of the role of urban vegetation (especially alien trees) in providing ES (and EDS) within this fine scale urban context.…”