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The distribution patterns and determinants of biodiversity in the Nama-Karoo Biome are poorly known. This poses a problem for conservation given the impact that future developments (e.g. uranium mining, fracking) and global climate change are likely to have on the region's biodiversity. This study investigated the potential role that several environmental and climatic variables play in determining species richness, relative cover, and growth form diversity in two habitat types: plains and rocky dolerite hillslopes. The study area extended over a 600 km longitudinal environmental gradient in the Upper Karoo in which mean annual precipitation varied from 100 to 600 mm from west to east. A pairwise floristic survey approach was implemented, using modified Whittaker plots in each habitat type at 30 sites within the shale gas exploration area in the Upper Karoo bioregion. The results showed that total species richness was significantly higher (p

The 75 000 ha, hyper-arid area of Riemvasmaak represents one of the first land restitution cases in post-apartheid South Africa. People who were forcibly removed in 1974 were resettled in 1995. We ...

This study used a fence-line contrast approach to investigate the long-term impact of high grazing pressure on the vegetation at a site in Namaqualand, South Africa. Forty pairs of permanently mark...

Tierberg-LTER is a research site established in 1987 in the semi-arid Succulent Karoo near Prince Albert in the Western Cape province, South Africa. The original purpose for its establishment was to study ecosystem dynamics and the drivers of vegetation in the context of historical land use. The large body of work that has materialised from Tierberg-LTER is grounded on extensive baseline data and has greatly influenced the broader Karoo literature. It stands as the only long-term ecological research facility for the semi-arid region of South Africa. The Karoo environment faces several new developments centred largely on the expanding energy sector. Under a changing climate, ecosystems will have to further adapt to the impacts of such developments. The future research programme for Tierberg-LTER will accordingly continue to focus on understanding Karoo ecosystem dynamics and drivers of climate and anthropogenic change at local scales, thereby informing management and mitigation of future development impacts. Among a growing network of Karoo research sites, Tierberg-LTER maintains a unique role for long-term and intensive research that will contribute significantly towards the South African Environmental Observation Network’s vision of furthering ecosystem integrity, societal prosperity and sustainable development.Keywords: arid environments, development, ecosystem dynamics, Karoo, rangeland management

The mediterranean ecosystems of the world harbor exceptional biodiversity, and factors such as livestock grazing which may negatively affect biodiversity are of global concern. The mediterranean ecosystems of southern Africa have only sporadically been exposed to high densities of indigenous herbivores and may not be as typically resilient to livestock grazing pressure as the savannah and grassland ecosystems of semiarid Africa. We investigate this issue by assessing the impacts of two contrasting livestock grazing intensities associated with communal and commercial ranching systems on the dwarf succulent shrublands of the Succulent Karoo in Namaqualand, South Africa. We interpret the results in terms of vegetation dynamics and the implications for the current debate on nonequilibrium rangelands. The results demonstrate that the relative extent of plant community divergence between the communal and commercial rangeland has been maintained over the past 10 years, overall and within different plant growth forms. Recruitment of certain palatable shrub species occurred on the heavily grazed communal rangeland, indicating that a further decline in their populations is not inevitable. Recruitment of the unpalatable shrub Galenia africana on the communal rangeland was disproportionately greater than that of the palatable species, reenforcing the dominance of this species. Due to the longevity of woody shrubs, short-term vegetation shifts are small, limiting the potential for the recovery of overgrazed shrublands during periods of low grazing pressure. The shift on the communal rangeland toward annuals and geophytes has increased the variability of forage production and contrasts with the dominance of dwarf shrubs on the commercial rangeland. Shrub-dominated ecosystems create the potential for forage storage and inter-annual transfer of excess production, buffering livestock numbers in the face of a fluctuating environment. Despite the semiarid nature of the area and contrary to the predictions of the nonequilibrium theory, livestock and vegetation in Namaqualand interact strongly, and a close relationship between livestock numbers and primary production persists over the long-term on the communal rangeland.

27 pages, figures, and tables statistics., This paper summarises innovative research into the assessment of longterm groundwater recharge from flood events in dryland environments of the Kuiseb (Namibia) and the Buffels (South Africa) rivers. The integrated water resource management (IWRM) policies and institutions affecting the exploitation of groundwater resources in each of these developing countries are compared. The relatively large alluvial aquifer of the Kuiseb River (∼240 Mm3) is recharged from irregular floods originating in the upper catchment. Reported abstraction of 4.6 Mm3 per year is primarily consumed in the town of Walvis Bay, although the groundwater decay (pumping and natural losses along the period 1983–2005) was estimated in 14.8 Mm3 per year. Recharge is variable, occurring in 11 out of 13 years in the middle Kuiseb River, but only in 11 out of 28 years in the middle-lower reaches. In contrast, the Buffels River has relatively minor alluvial aquifers (∼11 Mm3) and recharge sources derive from both lateral subsurface flow and floodwater infiltration, the latter limited to a recharge maximum of 1.3 Mm3 during floods occurring once every four years. Current abstractions to supply the adjacent rural population and a few small-scale, irrigated commercial farms are 0.15 Mm3 yr−1, well within the long-term sustainable yield estimated to be 0.7 Mm3 yr−1. Since independence in 1990, Namibia’s water resource management approach has focussed on ephemeral river basin management of which the Kuiseb BasinManagement Committee (KBMC) is a model. Here, some water points are managed independently by rural communities through committees while the national bulk water supplier provides for Walvis BayMunicipality from the lower aquifers. This provides a sense of local ownership through local participation between government, NGOs and CBOs (community-based organisations) in the planning and implementation of IWRM. Despite the potential for water resource development in the lower Buffels River, the scope for implementingIWRMis limited not only by the small aquifer size, but also because basin management in South Africa is considered only in the context of perennial rivers. Since 2001, water service delivery in the Buffels River catchment has become the responsibility of two newly created local municipalities. As municipal government gains experience, skills and capacity, its ability to respond to local needs related to water service delivery will be accomplished through local participation in the design and implementation of annual ‘integrated development plans’. These two case studies demonstrate that a variety of IWRM strategies in the drylands of developing countries are appropriate depending on scales of governance, evolving policy frameworks, scales of need and limitations inherent in the hydrological processes of groundwater resources., The study was funded by the 6th framework of the European Community through the project “FloodWater recharge of alluvial Aquifers in Dryland Environments”, WADE Project (contract no. GOCE-CT-2003-506680). Obbe Tuinenburg and the staff of Gobabeb Training and Research Centre are gratefully thanked for their assistance.

Data from 199 plots in the semi-arid Karoo showed that relationships between soil infiltrability and plant cover/species richness, as depicted by boundary lines, yielded ecological insights not evident if only commonly measured soil properties such as pH, electrical conductivity and the content of clay, silt, sand, nitrogen and carbon were considered. For example, the common grass Stipagrostis obtusa, herb Lepidium africanum and shrub Pentzia incana showed potentially maximal cover at high, low and intermediate infiltrability, respectively (r 2 > 0.65 for boundary lines derived by segmented quantile regression), but did not show distinct boundary lines for sand, silt or clay content data (r 2

Changes in species richness and vegetation composition in the diverse semi-arid Succulent Karoo vegetation of South Africa were investigated after 67 (1937–2004) years of rest from livestock grazing at the Worcester Veld Reserve (WVR). This 72 ha reserve lies in the Worcester-Robertson Valley, 140 km east of Cape Town, South Africa (33°39′S and 19°27′E). Vegetation change in 35 plots located on termitaria and 35 plots located in the insterstices between termitaria was assessed using field survey data and multivariate ordination techniques. Changes in plant cover and species composition on termitaria sites were consistently greater than for adjacent off termitaria sites. In addition, the north-facing slopes changed more than the south-facing slopes. There was a higher increase in diversity for off termitaria sites than for on termitaria sites. On termitaria, there was a general decrease in stem succulents, particularly Euphorbia mauritanica and an increase in long-lived evergreen shrubs and trees such as Pteronia incana and Rhus undulata. Most sites had similar compositional shifts primarily determined by their association with termitaria and secondarily with aspect. These findings suggest that a consistent directional change in vegetation composition has taken place as a result of protection from grazing. Contrary to the widely held view that a release from grazing has little benefit in degraded semi-arid vegetation, we find that a significant and predictable directional response to rest has occurred at this site over the study period.

Summary 1 Gradients of animal impact known as piospheres tend to develop around artificial watering points, particularly in arid zones. Such grazing gradients represent a potential opportunity for differentiating the long-term effects of livestock activity from other environmental patterns. In this study, the impact of watering point provision on the plant cover, species richness and community structure of Karoo shrublands, South Africa, was investigated in the context of the evolutionary history and current grazing management practices of the region. 2 The impacts of watering point provision were investigated by sampling plant cover and composition along transects placed at set distances, ranging from 10 m to 2200 m, from 11 watering points. 3 Karoo vegetation cover and structure are relatively resilient to livestock grazing. Karoo plant diversity, as measured by species richness, evenness and dominance, was not as resilient. Twice as many species decreased as increased near watering points. The majority of species that decreased were regarded as being highly palatable to livestock. Heavy grazing, leading to death or repeated reproductive failure, is the most likely mechanism leading to the decline of such species. 4 The highly disturbed area immediately adjacent to watering points was dominated by forbs and contained a large proportion of alien species. Adjacent to this was a zone dominated by widespread shrub species of medium to low palatability. Areas most distant from watering points contained a greater proportion of species known to be highly palatable to livestock. The ability of dominant Karoo shrubs to tolerate heavy grazing may have allowed rangeland managers to maintain stocking rates above that which can be tolerated by the majority of species but which are supported by a minority of grazing-tolerant species. 5 Synthesis and applications. Highly palatable species are more abundant in areas distant from water points. Larger paddocks therefore provide a refuge for sensitive species that might otherwise be lost from the rangeland as a whole. Species that tend to occur away from watering points represent potentially useful indicators of grazing pressure. The use of these species as indicators of rangeland condition among landowners should be promoted.

The communal areas of the semi-arid (200 mm) winter-rainfall Namaqualand region of South Africa are heavily utilised by a large number of subsistence farmers who keep sheep and goats. For several decades, farmers have maintained, on average, more than twice the number of animals on the rangeland than the number recommended by the Department of Agriculture for neighbouring commercial enterprises. As a result of the continuous high stocking densities, significant changes in the vegetation have taken place. Farmers are now heavily reliant on an annual flush of vegetation following winter rains to keep their livestock alive. Using a combination of empirical data and consensus agreement, a computer model is developed to describe the long-term climate, livestock and vegetation interactions on the communal rangelands and to investigate the impacts of a range of management strategies. The model suggests that the system (including livestock) is sustainable although not stable, and that its sustainability could be due to climatic variability. The model supports the view that when livestock numbers vary in a manner consistent with recorded observations herbivory has little long-term impact on productivity of the system. This supports recent views of rangelands in semi-arid and arid environments where non-equilibrium conditions are thought to dominate ecosystem processes.

Aloe pillansii is a large succulent tree confined to the hyper arid region of the Richtersveld and southern Namibia. Because of its narrow distribution, its small population size and decline in adult plant numbers it is considered an endangered species, susceptible to the impacts of climate change. Using two databases compiled for the 1 202 known South African individuals of the species we identified 10 sub-populations, defined as clusters of individuals within 2 km of their nearest con-specific neighbour. Seven sub-populations were located relatively close to each other in the northern part of their range while three were located together 60 km further south than this. Using correlation and multivariate ordination analyses of the environmental variables associated with each sub-population, we show that the sites of the southern populations are higher, cooler and wetter than their more northern counterparts, which were themselves divided into warm, low-lying sites in the west, with a predominance of winter rain, and moderately high elevation sites with more summer rain in the east. An examination of the height class frequency distribution of all South African individuals shows a bi-modal distribution with more than 25 % of the recorded individuals being less than 1 m in height. There is a significant decline in the 2- 4 m height class, but an increase to 5 m and a steady decline thereafter to the largest height class of 12 m. The best explanation for this pattern suggests that there has been poor recruitment in the species prior to the last 20 years, although theft and herbivory of small individuals might also explain the absence of 2-4 m high individuals in the population. The height class frequency distributions of the various sub-populations differ significantly. The three southern sub-populations exhibit a uni-modal distribution with a low proportion of seedlings and juveniles (individuals

Studies of land degradation in South Africa have seldom addressed the issue for the whole country. As part of the first step in developing a National Action Programme to combat desertification, a national review of the soil and veld degradation problem was conducted in 1997 and 1998. The results are based on the perceptions of agricultural extension workers and resource conservation technicians from the Department of Agriculture. They indicate that it is primarily in the communal areas along the eastern and northern escarpment and in some commercial districts along the Orange River that problems of soil degradation are greatest. Veld degradation is also higher in communal areas than commercial areas, although many commercial areas are susceptible to bush encroachment and alien plant invasions. A separate multiple regression analysis indicates that both biophysical and socio-economic factors are associated with high levels of soil and veld degradation. Magisterial districts which are most degraded are char...

Seed production and shrub association patterns of the twopalatable shrubs. Tripteris sinuatum and Tetragoma froticosa were investigated on heavily grazed communal and lightly grazed commercial rangeland in the succulent karoo. Namaqualand. Seed production in both these species was substantially reduced on the communal rangeland relative to the commercial rangeland. Seed production in T. sinuatum was most severely affected. with seed production on the communal rangeland two orders of magnitude lower than on the commercial rangeland. The proportion of T. sinuatum and T. froticosa shrubs growing unassociated with other shrubs on the communal rangeland was reduced by approximately 50%. Lycium ferocissimum was most effective as a refuge plant for T. sinuatum in terms of the mean seed production per plant. Ruschia robusta was however most important in terms of the overall amount of seed produced by T. sinuatum and T. froticosa on the communal rangeland. due to the large number of times this association occurred. Refuge plants did not appear to be particularly important for T. froticosa in terms of seed production, but were important in terms of providing safe sites for recruitment. The results of this study suggest that unpalatable or thorny species such as L. ferocissimum play an important role inproviding refuge sites for palatable species that might otherwise become entirely lost from overgrazed rangelands. African Journal of Range & Forage Science 17(1, 2&3): 22-26

Changes in plant species richness and community composition were investigated across a fence separating heavily grazed communal and lightly grazed commercial farming systems in Namaqualand, South Africa. No significant differences in plant species richness between communal and commercial farming systems were detected either locally within individual plots or overall across all plots. Within-plot, richness of species tolerant of grazing, such as annuals and geophytes, has increased, while the richness of large palatable shrub species has decreased on the communal rangeland. In terms of plant cover, species' responses to grazing were strongly associated with growth form. Annuals and geophytes formed the majority of grazing increasers, while large, presumably palatable, shrubs and leaf succulents were characteristic grazing decreasers. An investigation into population processes of five shrub species revealed that heavy grazing on the communal rangeland has resulted in: reduced size of palatable shrub species; reduced flower production and seedling recruitment of palatable species; increased density and recruitment of the unpalatable shrub, Galenia africana. Reductions in shrub volume, reproductive output and seedling recruitment were most marked in the palatable shrub Osteospermum sinuatum and were in the order of 90%. The results are further discussed in terms of their relevance to rangeland dynamics and the current land use practices of the region.

Impacts on the environment as a result of drought, land cover change, and invasive alien species have been extreme in some cases, with a concomitant reduction in ecosystem services and a decrease in several quality of life indicators for the most vulnerable people in the region. The effect of these different impacts on the provision of ecosystem services in the short and long terms is discussed. This review explores documented threats from climate impacts on the abiotic and biotic environments of Africa and its impact on ecosystem services and human well-being.

We investigate the correlates of stocking rate in the Leliefontein communal reserve and attempt to provide a mechanistic explanation of the controlling factors. We further speculate on how high stocking rates are maintained in relation to the current state of the rangeland and grazing practices in the region. Stepwise regression revealed that over 80% of the variance in stocking rate could be explained by the mean maximum temperature during the hottest month, February. Deeper investigation revealed that the proximity of the West Coast played an important role in moderating temperature across the reserve. Areas further inland were not only hotter in summer, but were also colder in winter. We speculate that despite large differences in rainfall, the temperature gradient results in a shorter growing season and hence lower productivity of areas further inland. Mean annual rainfall was a very poor predictor of stocking rate and explained less than 5% of the variance in stocking rate across the reserve. Within a single village district, the stocking rate over time was, however. correlated with rainfall over the same period, indicating that stocking rates are determined by primary productivity and are at, or close to, the ecologioal carrying capacity. We further argue that continuous grazing of the lowlands during the growing season has resulted in the lowlands becoming dominated by annuals and unpalatable shrubs. Due to the shallow-rooted nature of annuals, the vegetation has become more sensitive to temperature efficts. The reliability and seasonality of the rainfall in Namaqualand are seen as important factors contributing to the seasonal abundance of annuals and the viability of the current grazing system in the region.African Journal of Range & Forage Science 17(1, 2&3): 36-45

Much of the worlds biological diversity exists outside of a formal protected reserve network, often on land that is managed for some form of agricultural production and the maintenance of rural livelihoods. Effective biodiversity conservation will therefore require innovative ways to merge the needs of farmers and rural communities with the need to conserve globally significant biodiversity. One of the key questions in this process is who actually benefits from biodiversity conservation. If farmers and rural communities do not benefit from biodiversity conservation, then society needs to provide incentives to achieve conservation objectives on agricultural lands. However, farmers and rural communities rely on healthy ecosystems to provide goods and services to sustain agricultural production (Pagiola et al. 1997) and to improve their quality of life, and the maintenance of healthy ecosystems may also provide benefits for biodiversity conservation. An important first step is to identify and promote conservation farming practices that can meet both these needs.

Aspalathus linearis (Fabaceae) is endemic to the Cape Floristic Region in the Western Cape and Northern Cape Provinces of South Africa. The reddish leaves and stems, primarily of one cultivar, are used to make a commercially important tea which is marketed locally and internationally as ‘rooibos’ or ‘redbush’ tea. In historical times rooibos was collected in the wild. In the twentieth century cultivation of a single cultivar increasingly replaced wild harvest to meet growing demand. Recently, tea from wild forms of the species, which vary significantly in growth form and reproductive strategy, has been marketed by small-scale farmers in Wupperthal and on the Suid Bokkeveld plateau in the northern part of the species' distribution. Little information on the wild forms of this species has been published, although a rich body of knowledge exists amongst local harvesters and other land-users. In this study, we focus on the northern part of the species’ distribution area where wild rooibos is harvested for commercial sale to niche organic and fair-trade markets. We adopt a transdisciplinary approach to (1) document the different growth forms, (2) develop a bioclimatic model of the potential distribution of the species, (3) quantify the morphological variation that exists between growth forms relative to the established cultivar and (4) use molecular techniques to provide a preliminary insight into the infraspecific diversity of different wild A. linearis growth forms. Our results show that local land users in the region identify four main growth forms of wild A. linearis. These are an ‘erect form’ and a ‘prostrate form’ in the Wuppertal area, a ‘shrub form’ in the Suid Bokkeveld, and a ‘tree form’ that has been observed at specific sites at Wupperthal, Biedouw and the Suid Bokkeveld. The PCA analysis of seven morphological traits identified three growth forms, which support the land user descriptions except in the case of the 'tree' and 'erect' forms which co-occurred in coordinate space. Both shrub and prostrate forms are wider than they are taller and possess more stems closer to the ground than erect forms. While the stems of both shrub and prostrate forms lie relatively flat on the ground, stem thickness is significantly greater in shrub forms. The tree type, the erect form and the cultivar studied possess the highest harvestable biomass. Prostrate forms and shrub forms resprout after fire while erect and tree forms regenerate from seed only. Haplotypic variation was assessed using DNA sequences from a single chloroplast region and revealed strong genetic differences between the different growth forms. Although preliminary, there is some evidence that sprouting and nonsprouting forms of the species are genetically isolated. This has important taxonomic implications for the species. Additional chloroplast regions and a nuclear region were also identified as variable and potentially useful markers for a multi-locus molecular approach to studying taxonomic and ecological questions within the species.