Format: ORAL

Sandy-Lynn Steenhuisen1, Grant D. Martin1,2, Karabo T. Moloi1, Lehlohonolo D. Adams3, Stephanie L. Payne1, Onalenna Gwate1, Patricia Masole1, Lesego Malekana1, Colleen Downs3, Vincent R. Clark1

1 Afromontane Research Unit, University of the Free State, Phuthaditjhaba, South Africa. 2 Centre for Biological Control, Rhodes University, Makhanda, South Africa. 3 South African National Biodiversity Institute and Centre for Functional Biodiversity, University of KwaZulu-Natal, Pietermaritzburg, South Africa

Invasive fleshy-fruited Rosaceae are becoming problematic in the grasslands and mountains of South Africa, where they can have severe impacts. Here we review current and ongoing research into the expansion of these species. Plant reproductive ecology experiments have been conducted on a number of the most problematic invasive Rosaceae species. These have included determining seed production, soil seed banks, aviary feeding experiments with frugivorous birds, camera trapping and observations to determine frugivores in the field, and faecal seed counts. To determine altitude and climate impacts on their survival and growth, Rosaceae species were translocated and planted in both natural vegetation and in open top chambers at low and high altitude sites to represent future climate warming scenarios. Results show that these species produce millions of seeds/m2 invasion, which are long-lived in the soil. Fruits are eaten and dispersed by animals and different Rosaceae species appear dependent on different guilds of frugivores. Larger bird species, eland and baboons were highlighted as potential long distance dispersers. Transplant experiments show that these species are able to survive at high altitudes up to 3100 masl and future climates may favour their spread into mountain ecosystems. These invasive Rosaceae species possess several reproductive traits that make them formidable invaders and difficult to manage. More study is needed to understand all factors involved in exacerbating spread in warmer climate scenarios as climate change experiments suggest the entire altitudinal range of the Drakensberg Mountain system is suitable for the establishment of these invasive Rosaceae.