South Africa as a Donor of Naturalised and Invasive Plants to Other Parts of the World

Abstract

This chapter provides the first assessment of South African native vascular plants as naturalised and invasive species in other parts of the world. For naturalised species, Global Naturalized Alien Flora (GloNAF) data were used, while for invasive species an assessment was made using the peer-reviewed literature, experience of the authors, and correspondence with authorities in many parts of the world. Results show that 1093 South African native plant taxa have been recorded as naturalised, but for only 79 of these is there strong and unequivocal evidence of invasiveness in natural or semi-natural ecosystems (another 132 taxa have been listed as invasive, but do not fulfil all criteria for listing as such). Thirty-five taxa have naturalised in more than 100 regions (countries, states, provinces, districts, or individual islands), and six taxa (all grasses-family Poaceae) are naturalised in more than 200 regions. However, of these, only 12 (34.2%) are recorded as invasive, and only nine fulfil the more conservative definition of invasive. These figures indicate that to be widely distributed does not automatically translate into being a strong invader, and that taxa that are extremely successful as invaders in some regions only succeed in specific environmental and geographic settings, and many of them are not widespread alien plants. Grasses are over-represented among both naturalised and invasive South African plant exports: 15% of naturalised species and 23% of invasive species are grasses. Temperate Asia and Europe are net donors of naturalised plants to South Africa, but Australasia and the Pacific Islands have received many more naturalised plants than they have donated to South Africa. Of taxa native to South Africa recorded as unequivocally invasive outside of cultivation elsewhere, 65% occur in Australia. 26.1 Introduction Information on the global distribution of alien plant species has improved dramatically over the last decade (van Kleunen et al. 2015; Pyšek et al. 2017), largely due to the Global Naturalized Alien Flora database (GloNAF; www.glonaf.org) that integrates and summarises the wealth of regional data on the occurrence of naturalised alien plants worldwide (sensu Richardson et al. 2000b). In January 2019, GloNAF contained data on the distribution of 13,939 plant taxa in 1029 regions, including 381 islands (the regions in GloNAF correspond to countries, states, provinces, districts, or individual islands, see van Kleunen et al. 2019 for the full list). GloNAF has been used for testing a wide range of central concepts and hypotheses in invasion biology (see

Floristic composition and potential invasiveness of alien herbaceous plant in Western Mexico

“…Melinis repens, Natal grass, originated in Southern Africa and has an introduced range from Africa to Australia, Asia and America (Moore, 2010;Pyšek et al, 2020;Romero Martins et al, 2007). It was first recorded in the USA in the 19 th century (Stokes, 2010).…”

“…In Mexico it was first found in 1945 after it escaped from experimental cultivation (Itié, 1945). It is one of the most invasive species globally, and in Mexico it is also causing damage, especially by modifying fire regimes (Espinosa-García & Villaseñor, 2017;Gonçalves Rolim et al, 2014;Martínez-de la Cruz et al, 2015;Pyšek et al, 2020;Rzedowski & Calderon de Rzedowski, 1990;Space et al, 2000).…”

“…It was found to invade extreme sites, such as desert areas and bare volcanic rocks after eruptions (Aziz & Khan 1993;Rejmánek et al, 1982). Eragrostis ciliaris is known in Africa and Asia and is widely distributed in North and South America (Pyšek et al, 2020). The species is present but not highly invasive and does not cause damage to natural ecosystems in many of these regions (Gonçalves Rolim et al, 2014;Pyšek et al, 2020;Veldman, 2010).…”

“…Eragrostis ciliaris is known in Africa and Asia and is widely distributed in North and South America (Pyšek et al, 2020). The species is present but not highly invasive and does not cause damage to natural ecosystems in many of these regions (Gonçalves Rolim et al, 2014;Pyšek et al, 2020;Veldman, 2010). The species has been found in at least 20 of the 32 states in Mexico (Espinosa-García & Villaseñor, 2017), but there are no detailed data on its effects.…”

South Africa’s Centre for Invasion Biology: An Experiment in Invasion Science for Society

“…Many benefits for advancing invasion science have been created by working with researchers, and accessing funding, facilities and ideas. The C•I•B makes many of these connections through normal academic routes, such as participating in international conferences, notably the EMAPi conferences for plant-related work (Pyšek et al 2019(Pyšek et al , 2020, and making personal connections with international researchers through bilateral visits and shared students. Fig.…”