Impact of livestock grazing intensity on plant diversity of montane grassland in the northern Drakensberg, South Africa

Abstract

Communal livestock grazing is expected to impact botanical composition and plant diversity of Drakensberg montane grasslands. Accordingly, a grazing gradient extending outward from kraals, and fence-line contrasts between communal rangeland and protected areas (Golden Gate Highlands National Park and Royal Natal National Park), were studied in the QwaQwa region of South Africa. Presence of a grazing gradient was confirmed by a decrease in the amount of cattle dung with increasing distance from kraals that was independent of altitude, solar radiation, slope, or soil physico-chemical properties. Canonical correspondence analysis confirmed that grazing intensity had a significant influence on botanical composition although most compositional variation was unexplained. Higher grazing intensities tended to negatively affect plant species richness and diversity, and the cover of perennial graminoids, but benefitted the abundance of dwarf shrubs and alien invasive species. Similar effects were apparent across each of the fence line contrasts. Despite a long history of livestock grazing, communal rangeland supported >320 indigenous species, illustrating some contribution to biodiversity conservation, but being compromised near kraals. An improved approach for study of the impacts of livestock grazing on plant diversity is suggested that would overcome the difficulties of assessing rare and threatened species using a community approach.