Evidence for induced pseudo-vivipary in Pennisetum setaceum (Fountain grass) invading a dry river, arid Karoo, South Africa

We report the development of rootless plantlets in inflorescences of Pennisetum setaceum (Fountain grass) invasive in the Gamka River in the Karoo National Park, South Africa. The pseudo-vivipary appeared to have been induced by inundation of immature inflorescences when the river flooded. Plantlet production may facilitate the spread of this species in seasonally flooding rivers in arid regions. To the best of our knowledge this is the first record of induced pseudo-vivipary in this grass species

Evidence for induced pseudo-vivipary in Pennisetum setaceum (Fountain grass) invading a dry river, arid Karoo, South Africa

We report the development of rootless plantlets in inflorescences of Pennisetum setaceum (Fountain grass) invasive in the Gamka River in the Karoo National Park, South Africa. The pseudo-vivipary appeared to have been induced by inundation of immature inflorescences when the river flooded. Plantlet production may facilitate the spread of this species in seasonally flooding rivers in arid regions. To the best of our knowledge this is the first record of induced pseudo-vivipary in this grass species

Effects of invasion of fire-free arid shrublands by a fire-promoting invasive alien grass (Pennisetum setaceum) in South Africa

Arid shrublands in the Karoo (South Africa) seldom accumulate sufficient combustible fuel to support fire. However, as a result of invasion by an alien perennial grass (Pennisetum setaceum), they could become flammable. This paper reports on an experiment to assess the effects of fire following invasion by P. setaceum.We established 10 plots (5 ¥ 10 m) separated by 2.5 m, and added grass fuel to five plots (5 and 10 tons ha-1 to alternate halves of the plot) leaving the remaining five plots as interspersed controls. Plots with fuel added were burnt, and fire behaviour was measured during the burns. Rates of fire spread were generally low (0.01–0.07 m s-1) and did not differ significantly between burn treatments. Mean fireline intensities were higher in the high compared with the low fuel treatments (894 and 427 kW m-1, respectively).We recorded plant species and their cover before and after burning on each of the plots. After 15 months of follow-up monitoring in the burn plots, only two species, the dwarf shrub (Tripteris sinuata) and the perennial herb (Gazania krebsiana) resprouted. Most individuals of other species were killed and did not reseed during the 15-month study. The mass of added fuel load (high or low) did not influence vegetation recovery rates after fire. Should future invasions by P. setaceum lead to similar fuel loads in these shrublands, inevitable fires could change the vegetation and may favour spread of the flammable grass. Our results have important implications for predicting the effects of invasive alien plants (especially grasses) on fire-free ecosystems elsewhere.The predicted impacts of fire may alter species composition, ultimately affecting core natural resources that support the Karoo economy.This study was funded by DST – NRF Centre of Excellence for Invasion Biology, Stellenbosch University, South Africa

The role of environmental factors in promoting and limiting biological invasions in South Africa

CITATION: Wilson, J.R. et al. 2020. The role of environmental factors in promoting and limiting biological invasions in South Africa. In: Biological Invasions in South Africa. van Wilgen, B.W., Measey, J., Richardson, D.M., Wilson, J.R. and Zengeya, T.A. (eds.). Springer, Cham. pp. 355-385. doi:10.1007/978-3-030-32394-3_13The original publication is available at https://link.springer.com/book/10.1007/978-3-030-32394-3This chapter provides an overview of the researchers and research initiatives relevant to invasion science in South Africa over the past 130 years, profiling some of the more recent personalities, particularly those who are today regarded as international leaders in the field. A number of key points arise from this review. Since 1913, South Africa has been one of a few countries that have investigated and implemented alien plant biological control on a large scale, and is regarded as a leader in this field. South Africa was also prominent in the conceptualisation and execution of the international SCOPE project on the ecology of biological invasions in the 1980s, during which South African scientists established themselves as valuable contributors to the field. The development of invasion science benefitted from a deliberate strategy to promote multi-organisational, interdisciplinary research in the 1980s. Since 1995, the Working for Water programme has provided funding for research and a host of practical questions that required research solutions. Finally, the establishment of a national centre of excellence with a focus on biological invasions has made a considerable contribution to building human capacity in the field, resulting in advances in all aspects of invasion science—primarily in terms of biology and ecology, but also in history, sociology, economics and management. South Africa has punched well above its weight in developing the field of invasion science, possibly because of the remarkable biodiversity that provided a rich template on which to carry out research, and a small, well-connected research community that was encouraged to operate in a collaborative manner.https://link.springer.com/chapter/10.1007%2F978-3-030-32394-3_13Publisher’s versio