Impacts of Neltuma velutina in South Africa
Neltuma velutina (Fabaceae: EPPO List of Invasive Alien Plants) is native to North America and occurs in Israel, Jordan, Morrocco, and Spain. It has been planted around the world as a fodder plant, for shade, and for erosion control. Seeds are sometimes available via mail order and via horticultural suppliers. Negative impacts can include impacts on biodiversity and ecosystem services. In South Africa, N. velutina is considered an invasive alien species and is common along the Molopo River in the North-West Province. To evaluate its impact, three study sites were selected in a semi-arid area of the Savana biome where N. velutina was dominant. Each site was compared to an adjacent area where N. velutina was absent or in such low numbers that its presence could not have an effect on the composition of native vegetation. Five quadrats (20 x 20 m) were set up in each site and in each quadrat all native woody plant species were identified. The results showed that the density of native woody plants was significantly lower in invaded stands compared to non-invaded ones. In addition, overall, species diversity, species evenness and species richness were lower in invaded sites compared to non-invaded sites. The vigorous and rapid growth of N. velutina can have detrimental impacts on native plant species but N. velutina can also have indirect impacts with a higher utilisation of valuable resources. It has a deep and extensive root system that can deplete groundwater causing water shortages to native tree species.
Sources
Tiawoun MAP, Malan PW, Comole AA, Moshobane MC (2023) Impact of Prosopis velutina Wooton on the composition and diversity of native woody species in a semi-arid zone along the Molopo River, South Africa. Plants 12, 1561. https://doi.org/10.3390/plants12071561