Linking riparian vegetation types and fluvial geomorphology along the Sabie River within the Kruger National Park, South Africa

Abstract

Vegetation types were studied in relation to the fluvial geomorphology along the mixed bedrock‐alluvial Sabie River within the Kruger National Park, Mpumalanga, South Africa. Six vegetation types were identified using TWINSPAN analysis, namely: Phragmites mauritianus, Phyllanthus reticulatus, Breonadia salicina, Combretum erythrophyllum, Diospyros mespiliformis and Spirostachys africana vegetation types. Spirostachys africana and Diospyros mespiliformis vegetation types were found to occur predominantly on the stable, infrequently flooded macro‐channel banks, while the remaining four vegetation types were found almost exclusively along the more geomorphically and hydrologically dynamic macro‐channel floor. The degree of bedrock or alluvial influence was identified as being an integral factor in the distribution of the four macro‐channel floor vegetation types at both the morphological unit and the channel type scale. The geomorphological continuum from the bedrock influenced bedrock anastomosing channel types, to mixed anastomosing and pool‐rapid channel types, to the fully alluvial braided channel types, is reflected in the change in species composition from Breonadia salicina vegetation type, to Phyllanthus reticulatus and Phragmites mauritianus vegetation types, to Combretum erythrophyllum vegetation types, respectively. Given the vegetation/fluvial geomorphology links established, changes in vegetation composition are proposed in response to scenarios of geomorphological change as a result of progressive sedimentation.