We analysed the extent of ecological damage of gully and inter-gully erosion in a sub-catchment situated in the drylands (300 mm yr À1 ) of the winter rainfall area of South Africa where small-stock farming on rangeland is the main source of income. We applied low-cost measures to revegetate the bare sites of the inter-gully erosion and stabilised gully erosion by loosening soil surfaces and applying geotextile and constructing check dams to reverse gully erosion. We compared vegetation cover, silt accumulation and penetration resistance of the soil upslope of the check dams with the situation downslope of the check dams and untreated gullies as controls. For the treated bare patches, we compared penetration resistance and vegetation cover with untreated controls. Two years after implementation, the restoration measures resulted in increased soil depth and vegetation cover upslope of the check dams and increased vegetation cover on the treated bare patches. We calculated the net present value of the restoration measures based on the financial benefit that a landowner can realistically expect under current economic and governance conditions (i.e. payment for additional livestock and for C sequestration). At the current rates of return for livestock production or carbon sequestration over a 20-year period, rehabilitation of this sort is not financially feasible for private landowners. Either the current payment for carbon sequestration would have to be increased by a magnitude of 40-80, or restoration measures would have to be funded by the public or private sector to make them financially viable for landowners.

Abstract:Fire is known to be an important element shaping semi-arid ecosystems. Within SASSCAL we conducted several projects in the woodland savanna of the Waterberg Plateau Park to gain a better understanding of the impact of fi re on ecosystem properties and processes (soil characteristics, species composition and structure of the vegetation, changes in plant forage quality, insect biodiversity, and the utilization of habitat and plants by large herbivores). Four adjacent areas of around 2,000 ha-2,500 ha each with diff erent times since last burn were studied (in 2014, when most of the measurements were done, the areas had been burnt 2, 3, 14, and 24 years prior to the study). We found inconsistent eff ects of diff erent fi re histories on soil nutrients, soil organic carbon, and soil respiration, which suggests that soil resources return rapidly (within a year or two) to pre-fi re conditions at our sites. We also assume (based on the standing biomass of the four areas during the study) that the fi res were likely to have not been suffi ciently intense to cause long-term detrimental impacts and impair the recovery of soil resources at our sites. Furthermore, fi re positively aff ected the grass component by increasing grass density and enhancing productivity. Fire maintained open savannas through the top-kill of woody plants but did not alter plant species composition. The infl uence of burning on the quality of grasses was relatively short-lived (two years after burning, grass quality in burnt sites was comparable with that of unburnt sites). However, trees, whose leaves are generally higher in protein, remained at a higher quality for longer periods after fi re and thus served as supplementary food not only for browsers and mixed feeders but also for herbivores generally considered to be 'pure' grazers (e.g., red hartebeest, buff alo). Fire had a negative impact on small ground-nesting bees, whereas bigger and above-ground-nesting bees seemed to be favoured by fi re.Ground-dwelling invertebrate communities diff ered with time since last burn, the main driver of the diff erences being litter cover. Our fi ndings in relation to fi re illustrate that heterogeneous habitats, as a result of pyrodiversity, are of great benefi t for the habitat utilization and plant utilization of large herbivores as well as increasing the overall diversity of invertebrates.Managers can maximise biodiversity and diversity in resource and habitat utilization by maximising the diversity of fi re histories in the managed areas (commonly termed patch-mosaic burning).Resumo: O fogo é conhecido por ser um importante factor na modelação dos ecossistemas semi-áridos. No contexto do SASSCAL, realizámos vários projectos na savana arborizada do Parque Nacional de Waterberg, de modo a obter uma melhor compreensão do impacto do fogo nas propriedades e processos do ecossistema (características do solo, composição e estrutura da vegetação, alterações na qualidade de forragem, biodiversidade de insectos e utilização do habitat e das plantas pelos...