The extent of African elephant (Loxodonta africana) induced damage on shrub and mature Baikiaea plurijuga trees was investigated around artificial and natural watering points in northern Hwange National Park, Zimbabwe. Damage was assessed in three zones of elephant occupancy during the dry season i.e. high elephant occupancy zone (≤ 1 km from water points), moderate elephant occupancy zone (> 1-2 km from water points) and low elephant occupancy zone (> 2 km from water points). A total of 48 plots along baseline transects were sampled among four artificial watering points and four natural watering points at increasing distance from the watering points. Damage to recruits, mature B. plurijuga and overall woody vegetation decreased with distance from artificial watering points. In addition, damage to mature B. plurijuga and overall woody vegetation decreased with distance from natural watering points, whereas damage to recruits did not change with distance from water points. Our results show that artificial watering points are associated with higher damage to B. plurijuga recruits and overall woody vegetation within ≤ 1 km radius from water points compared to natural watering points. Other changes associated with increasing distance from artificial watering points were increase in canopy cover and decrease in woody species diversity. In the natural watering points, we recorded an increase in canopy cover, mean basal area of B. plurijuga shrubs and height B. plurijuga shrubs, and a decrease in species diversity with distance from watering points. Overall, woody species diversity was higher around natural watering points than around artificial watering points. Our findings suggest that browsing by large herbivores near watering points leads to the degradation of vegetation.

Southern Africa is particularly sensitive to climate change, due to both ecological and socioeconomic factors, with rural land users among the most vulnerable groups. The provision of information to support climate-relevant decision-making requires an understanding of the projected impacts of change and complex feedbacks within the local ecosystems, as well as local demands on ecosystem services. In this paper, we address the limitation of current approaches for developing management relevant socio-ecological information on the projected impacts of climate change and human activities. We emphasise the need for linking disciplines and approaches by expounding the methodology followed in our two consecutive projects. These projects combine disciplines and levels of measurements from the leaf level (ecophysiology) to the local landscape level (flux measurements) and from the local household level (socio-economic surveys) to the regional level (remote sensing), feeding into a variety of models at multiple scales. Interdisciplinary, multi-scaled, and integrated socio-ecological approaches, as proposed here, are needed to compliment reductionist and linear, scalespecific approaches. Decision support systems are used to integrate and communicate the data and models to the local decision-makers.Observed temperature increases over large parts of South Africa during the period 1931-2015 have occurred at rates of about twice the global mean, and this trend is projected to continue into the future (DEA 2017). Other projections across Southern Africa include changes in rainfall amount, variability, intensity and seasonality, and increases in the likelihood of extreme

Abstract. Climatic and land management factors, such as water availability and grazing intensity, play an important role in seasonal and annual variability of the ecosystem–atmosphere exchange of CO2 in semi-arid ecosystems. However, the semi-arid South African ecosystems have been poorly studied. Four years of measurements (November 2015–October 2019) were collected and analysed from two eddy covariance towers near Middelburg in the Karoo, Eastern Cape, South Africa. We studied the impact of grazing intensity on the CO2 exchange by comparing seasonal and interannual CO2 fluxes for two sites with almost identical climatic conditions but different intensity of current and historical livestock grazing. The first site represents lenient grazing (LG) and the vegetation comprises a diverse balance of dwarf shrubs and grasses, while the second site has been degraded through heavy grazing (HG) in the past but then rested for the past 10 years and mainly consists of unpalatable grasses and ephemeral species. Over the observation period, we found that the LG site was a considerable carbon source (82.11 g C m−2), while the HG site was a slight carbon sink (−36.43 g C m−2). The annual carbon budgets ranged from −90 ± 51 g C m−2 yr−1 to 84 ± 43 g C m−2 yr−1 for the LG site and from −92 ± 66 g C m−2 yr−1 to 59 ± 46 g C m−2 yr−1 for the heavily grazed site over the four years of eddy covariance measurements. The significant variation in carbon sequestration rates between the last two years of measurement was explained by water availability (25 % of the precipitation deficit in 2019 compared to the long-term mean precipitation). This indicates that studied ecosystems can quickly switch from a considerable carbon sink to a considerable carbon source ecosystem. Our study shows that the CO2 dynamics in the Karoo are largely driven by water availability and the current and historical effects of livestock grazing intensity on aboveground biomass (AGB). The higher carbon uptake at the HG site indicates that resting period after overgrazing, together with the transition to unpalatable drought-tolerant grass species, creates conditions that are favourable for carbon sequestration in the Karoo ecosystems, but unproductive as Dorper sheep pasture. Furthermore, we observed a slight decrease in carbon uptake peaks at the HG site in response to resuming continuous grazing (July 2017).

<p>South African ecosystems are highly vulnerable to the effects of climate change, such as increasing temperatures, modifications in rainfall patterns, increasing frequency of extreme weather events and fire, and increased concentration of atmospheric carbon dioxide (CO<sub>2</sub>). At the same time, ecosystems are impacted by livestock grazing, cultivation, fuelwood collection, urbanization and other types of human land use. Climatic and land management factors, such as water availability and grazing intensity, play a dominant role in influencing primary production and carbon fluxes. However, the relative role of those parameters still remains less known in many South African ecosystems. Investigation of the carbon inter-annual variability at dwarf shrub Karoo sites will assist in understanding savanna dynamics and in constraining climate change scenarios as basis for climate adaptation strategies. </p><p>This research is part of the EMSAfrica (Ecosystem Management Support for Climate Change in Southern Africa) project, which aims at producing data and information relevant to land users and land managers such as South African National Parks (SANParks). A particular focus is given on the importance of carbon cycling in degraded vs. intact systems. We investigate the impacts of climate parameters and diverse land management on ecosystem-atmosphere variability of carbon fluxes, latent and sensible energy. Long-term measurements were collected and analyzed from two eddy-covariance towers in the Karoo, Eastern Cape, South Africa. Study areas had almost identical climatic conditions but differ in the intensity of livestock grazing. The first site represents controlled grazing and comprises a diverse balance of dwarf shrubs and grasses, while the second site is degraded through overgrazing in the past (rested for approximately 8 years) and mainly consists of unpalatable grasses and short-lived species. These ecosystems are generally characterized by alternating wet (December to May) and dry seasons (June to November) with the amount and distribution of rain (average 373 mm per year) and soil moisture as the main drivers of carbon fluxes. We observed peak CO<sub>2</sub> uptake occurring during the wet season (January to April) and a progressive decrease from wet to dry periods being highly controlled by the amount of precipitation. At the end of the observation period (November 2015 – November 2019), we found that both study sites were considerable carbon sources, but during wet periods 'overgrazed in the past' site had stronger carbon sequestration compared to 'controlled grazing' site. The higher carbon uptake could be an indication that resting of the highly degraded site for a long period may improve carbon uptake in the Karoo ecosystems. Our study shows that CO<sub>2</sub> dynamics in the Karoo are largely driven by water availability and the effects of grazing intensity on above-ground biomass.</p>