Spatio-temporal changes in the riparian vegetation associated with the Grassland Biome section of the Olifants River, Mpumalanga, South Africa

Abstract

The spatio-temporal changes over a 25-year period in the plant communities associated with the macro-channel of the Olifants River in the Mesic Highveld Grassland in the Mpumalanga Province, South Africa, were investigated. An area-based variable belt transect was used to resurvey selected sites which were previously surveyed roughly 25 years ago. Species richness increased from upstream to downstream driven by high influxes from specifically herbaceous species. Trends in vegetation cover varied from an increase in canopy cover in the upstream plant communities to a decrease in mid-to-downstream plant communities. The woody component increased in upstream communities, altering the riparian vegetation structure within the Grassland Biome section and resulting in spatial changes. The observed human-induced disturbances, such as livestock grazing, fire and river regulation, in conjunction with natural disturbances such as floods, contributed to the observed spatio-temporal changes. This study establishes a foundation for examining various disturbances, ranging from local to landscape levels, to develop research-based management guidelines tailored to different land uses.