The ecological and economic consequences of changing land use in the southern Drakensberg grasslands, South Africa

The grassland biome of the southern Drakensberg region of South Africa is characterized by a relatively rich floral biodiversity, including a high level of endemics.  Land use in the area was traditionally dominated by livestock ranching based mainly on indigenous grassland that conserved biodiversity to some degree.  Currently however, market demands and risk factors are shifting land use in the area to a matrix of beef, cropping, dairy and particularly, towards plantation forestry.  A spreadsheet model was constructed to understand how expected land use conversion will likely influence the biodiversity, and consequently, the total economic value (TEV) of the area.  Six scenarios of increasing dairy and forestry intensification were modelled that incorporated biophysical and legal constraints to development.  Results indicate that enhanced development is likely to have significant negative biodiversity impacts including the reduction of the alpha diversity of the indigenous plants in the region, a diminished local invertebrate diversity, an increase in invasions, and could also jeopardize the long term survival of the rare Wattled Crane and Oribi.  Furthermore, while the direct use value derived from agriculture and forestry increases with increasing development, its negative influence on the indirect value of water runoff, by far the greatest value of the area, is sufficient to potentially offset the benefits.  Other major direct-use, indirect-use, option and existence values are also considered.