The influence of anthropogenic impacts from development and human activity in and around foredune plant communities along a portion of the KwaZulu-Natal coastline.
The impact of development on coastal ecological processes within the coastal zone is often noted as being of ecological concern, due to the suggested destabilization of dune systems as a result of construction activities and post construction impacts such as stormwater disposal, trampling and other artificial influences on, in particular, the plant ecology of the frontal dune systems. Given that the stability of frontal dune systems along the Kwa Zulu Natal north coast is often attributed to the maintenance of vegetation and seral progression on such systems, the identification of changes in dune plant communities that may arise from the influence of proximal or adjacent activities was sought to be identified. Utilising data collected from a number of sites in the Kwa Dukuza Municipal area, the classification and ordination of environmental and botanical species information collated over approximately 6 months was undertaken. The results of this investigation indicate that: Species composition differs in terms of richness and abundance in the three frontal dune vegetation zones sampled. 2 3 4 5 Some species occur in all three zones and others are confined to one zone only. Bearing and the associated influence of wind, the slope and length of the beach, and the steepness ofthe dune face all influence the species composition at any particular site The influence of anthropogenic activities on dune synusia is such that human influence on one species may disrupt associations between species and may result in attenuation or '" reversal of seral movement. Anthropogenic impacts influences species composition at different sites by causing some species to decline abundance or disappear from a site and others to invade or oust established species. In Zone I the species that appears to be most affected by human activity is Gazania rigens, which appears to dominate in sites of high human activity, at the expense of Sporobolus virginicus. In Zone IT under high human activity species such as Cynanchum obtusifolium, Rhoicissus digitata and Sporobolus virginicus dominate, while the woody species Mimusops caffra and Eugenia capensis, as well as the liane Gloriosa superba appear to decline or be ousted from this Zone. In Zone Ill, Asystasia gangetica, is a dominant species where low to moderate human impacts are encountered, while where human impacts are high, species common to Zone I, such as G rigens may become prevalent, ousting A gangetica and grasses such as S virginicus may be ousted by more competitive species such as Stenotaphrum secundatum. It is thus concluded that human activities in and around the frontal dune system may be influential in re-inforcing aeolian impacts on sites with bearings affected by strong prevailing winds.