Browsing by Author "Steed, Adam John"
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- ItemThe effect of farmland abandonment on dung beetle diversity and function in the Nama-Karoo, Northern Cape, South Africa.(Stellenbosch : Stellenbosch University, 2020-03) Steed, Adam John; Roets, Francois; Crous, Casparus J.; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.ENGLISH ABSTRACT: Agricultural land abandonment has cascading effects on native biota. When badly managed, pressures on native biota can increase leading to reduced ecosystem function. Conversely, increased ecosystem function can result after decreasing anthropogenic pressures. This phenomenon has received little attention in the often-overexploited arid rangeland areas of the world. Here, I used a keystone taxon, dung beetles, as a bioindicator of the effect of farmland abandonment in the Nama-Karoo of South Africa. I documented changes in dung beetle abundance, richness, community assemblage composition, and their functional diversity as a result of ceasing large-scale sheep farming and evaluated differences in these factors across different biotopes. Dung beetles were sampled using baited pitfall traps on farms that were abandoned a long time ago (>10 years), recently (ca. 1 year ago) and on active farms, as well as from three dominant biotopes (hills, flatlands and ephemeral riparian zones) using three dung types (omnivore = pig; ruminant non-pelleted = cow; and ruminant pelleted = sheep). In general, riparian systems and flatlands had greater dung beetle richness, abundance, biomass and functional richness in comparison with hills, and each had a unique assemblage composition. Therefore, the flatland and ephemeral riparian areas that are generally most severely impacted by anthropogenic actions (since rocky slopes inhibit grazing activities) are particularly important for conserving dung beetle ecosystem functions and services. Dung beetle richness, abundance, and functional richness was higher in abandoned farmland areas due to greater dependence on omnivore and cow dung than on sheep dung, and reduced pressures on remaining native vertebrates. However, large-bodied dung beetles became rare after farmland abandonment. I therefore strongly encourage the reintroduction of native meso-herbivores to enhance dung resources in these abandoned areas, which will support higher dung beetle diversity, greater ecosystem function and increased ecosystem services.