The influence of adjacent land-use on road verges in the Swartland Region, South Africa.

Natural biodiversity is under threat from habitat destruction and fragmentation, partially caused by roads. Road verges provide potential avenues for invasion of alien species, while at the same time offering connectivity of the landscape on a large scale. This study aims to assess the ecological health of road verges in the Swartland area, South Africa and make recommendations on mitigating the threat of aliens while at the same time maximising biodiversity conservation. Road verges adjacent to non-agricultural areas showed lower species richness, while species abundance differed significantly (Mann-Whitney U-tests, p < 0.05) to most other land-uses. When comparing crop types, road verges adjacent to wheat fields differed significantly to all other crops types (Mann-Whitney U-tests, p < 0.05), with the lowest number of species encountered per transect. Jaccard Similarity Indices showed that samples differed in species composition, relative to adjacent land-use. It is recommended that road verges should be adaptively managed to promote recruitment of natural species and suppress the establishment of exotics. Where possible, road verges should be made as wide as possible to promote their use as refugia by various fauna. Finally, more extensive research efforts should be poured into road verges in order to fully realise their potential.