Effects of goat pastoralism on ecosystem carbon storage in semiarid thicket, Eastern Cape, South Africa

Abstract

Intensive pastoralism with goats transforms semiarid thicket in the Eastern Cape, South Africa from a dense vegetation of tall shrubs to an open landscape dominated by ephemeral grasses and forbs. Approx. 800 000 ha of thicket (which prior to the introduction of goats had a closed canopy and a Portulacaria afra Jacq. component) have been transformed in this manner. Ecosystem C storage in intact thicket and loss of C due to transformation were quantified. Carbon storage in intact thicket was surprisingly high for a semiarid region, with an average of 76 t C ha −1 in living biomass and surface litter and 133 t C ha −1 in soils to a depth of 30 cm. Exceptional C accumulation in thicket may be a result of P. afra dominance. This succulent shrub switches between C 3 and CAM photosynthesis, produces large quantities of leaf litter (approx. 450 g m −2 year −1 ) and shades the soil densely. Transformed thicket had approx. 35% less soil C to a depth of 10 cm and approx. 75% less biomass C than intact thicket. Restoration of transformed thicket landscapes could consequently recoup more than 80 t C ha −1 .

The effects of land use on honey bee (Apis mellifera) population density and colony strength parameters in the Eastern Cape, South Africa

“…The possibility of species extinction and climate change is magnified through deforestation which often accompanies agriculture (Whitmore and Sayer 1992). In the Eastern Cape, South Africa specifically, livestock farming can affect wildlife populations and plant structure and diversity negatively for small animals such as lizards and arthropods (Kerley et al 1995;Fabricius and Burger 1996a, b;Fabricius et al 1996a, b;Mills et al 2005;Lechmere-Oertel et al 2005). Its effects on honey bee colony strength parameters in the Eastern Cape was a subject of the research presented herein.…”

“…Furthermore, agricultural practices have been a serious threat to rare plants found in Cape lowlands (Heydenrych et al 1999) and the Eastern Cape region (Victor and Dold 2003). When farming livestock, much of the natural landscape is removed to accommodate pastureland for grazing livestock, which often leads to overgrazing (Kerley et al 1995, Mills et al 2005 and other land quality issues. When allowed to regenerate, natural vegetation and food webs could take an unpredictable amount of time to return to pristine condition, possibly being transformed forever through extinctions (Whitmore and Sayer 1992, Novacek and Cleland 2001).…”

Predictions of soil surface and topsoil organic carbon content through the use of laboratory and field spectroscopy in the Albany Thicket Biome of Eastern Cape Province of South Africa

“…The study area was a transect of approximately 130 km running in a south east (SE)-north west (NW) direction within the ATB (SE extreme: 25.38 E; NW extreme: −32.59 S). The study area was characterized by geological formation of mudstone, shales and sandstones (Mills et al, 2005). Soil types included Calcaric Cambisols, Calcic Luvisols, Rhodic Luvisols, and Calcaric Regosols (FAO, 1998).…”

Analysis and evaluation of ecological restoration experiments in the Succulent Karoo (South Africa)

“…Atriplex lindleyi ssp. inflata is an alien chenopod saltbush native to Australia and occurs often in areas which experienced overstocking (Mills et al 2005). …”