Abstract:
Many studies that evaluate rehabilitation make use of invertebrate bioindicators. Invertebrates,
especially ants, make useful indicators as they are sensitive to environmental change. We
compared ant assemblages in rehabilitated and control sites in the Rietvlei Nature Reserve, a
protected area important for grassland conservation in South Africa. Pitfall traps were used to
sample ant assemblages at six control sites and six rehabilitated sites. In addition, environmental
and vegetation surveys were conducted at each site. We found that the ant assemblages
differed significantly between the control and rehabilitated sites, although there was
considerable overlap; the control sites supported a greater species density and higher
abundance of ants than the rehabilitated sites. In total, 36 ant species were collected (control
sites: 34 species; rehabilitated sites: 26 species). The environmental survey revealed that
percentages of bare ground and coarse sand, as well as soil pH, differed significantly between
the control and rehabilitated sites. The control and rehabilitated sites also supported
significantly different plant assemblages. Three indicator ant species were identified for the
control sites: Crematogaster rectinota, Crematogaster amita and Monomorium fastidium. No
indicator species were identified for the rehabilitated sites. These results suggest that recovery
from the previous agricultural use of the area is still incomplete and highlights the lack of
research examining the success of rehabilitation in the grassland biome.
CONSERVATION IMPLICATIONS : The present study illustrates the need for further research on
rehabilitation techniques utilised in the grassland biome. This is of value as the remainder of
South African grasslands are considered critically endangered.
