Description of reference conditions for restoration projects of riparian vegetation from the species-rich fynbos biome

AbstractWhen considering revegetation strategies for particular restoration projects, data on community composition and structure should, whenever possible, be obtained from reference sites. Revegetation is an important restoration strategy especially since riverbanks that have been cleared of alien vegetation are extremely susceptible to erosion. The presence of lateral zonation in riparian vegetation is well documented: flooding events shape the vegetation on riverbanks and the zones that are inundated annually have different vegetation than those that are inundated interannually. This can be referred to as the demerse ecotope, or Wet Bank, and the emerse ecotope, or Dry Bank, and these zones can also be further subdivided. There is a need for species descriptions from undisturbed riparian zones to guide post-project appraisal and revegetation strategies, especially in areas with high species turnover like the fynbos biome. Braun–Blanquet vegetation belt transects were sampled on five undisturbed rivers that originate in the Hottentots Holland mountain range. Relevés were sampled from as many Wet Bank and Dry Bank subzones as were present in each case. Twenty-six riparian communities were recognized, which were clustered into ten community Groups based on physical bank attributes. The most dominant species for each of these community types have been listed in a synoptic table that can be used for revegetation purposes. It is recommended that revegetation plans make use of a mixture of the listed species, whilst maintaining separation of Wet and Dry Bank species. Prior to species selection, it is necessary to assess the range of riparian habitats available in the project reach. Though revegetation is more expensive than allowing for natural recruitment, recent evidence has shown that recovery of the natural vegetation without intervention may be limited, and not without risks. Revegetation may be a cheaper strategy in the long term, avoiding the maintenance costs that are required to stabilize banks and to remove re-invading alien species