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

Abstract

The spatio-temporal changes in plant communities along the macro-channel of the Olifants River in the Central Bushveld were investigated over a 26-year period. A variable belt transect method was used to resurvey selected sites previously assessed approximately 26 years ago. Species richness increased from upstream to downstream, driven by an influx of forbs, dwarf shrubs, and shrubs, with a notable rise in naturalised alien and invasive alien species. Canopy cover changes varied within and between plant communities, increasing in the upstream and downstream sections but decreasing in midstream areas. These shifts in species richness, canopy cover, composition and structure suggest a response to land use and integrated disturbance regimes, including river regulation, commercial and subsistence agriculture, development and conservation efforts, which interact with natural disturbances such as floods amid climate change. This underscores the need for stricter implementation and monitoring of legislation to protect water resources at the land-use level and preserve the natural functionality of riparian systems.