Stocking rate of extensive land-reform livestock farmers during 2018/2019 drought: Bloemfontein grassland biome case study

The study aimed to determine the average stocking rate among land reform beneficiary farmers specialising in livestock production in order to establish differences between calving percentage, fodder availability, and mortality rate of sampled farms, as well as to compare forage scarcities of Land Reform farms with their neighbouring farms during the midsummer drought of 2018/2019 in the Bloemfontein area. The average stocking rate was 5.9 ha/LSU in comparison with the Departmental grazing capacity norm of 6 ha/LSU for rangeland in good condition. However, 31% of the sampled farms were found to be severely overstocked, and the mortality rate on these farms, in relation to grazing capacity of 6 ha/LSU, was significantly higher (P < 0.05) than the mortalities on the other remaining farms. Naturally available fodder was found to be heterogeneous, with 37.9% of the respondents observing their available fodder as worse than that of their neighbours. The total mortality of 176.77 LSUs was recorded for the 29 sampled farms. These findings will assist the local extension personnel prevent future rangeland condition degradation and increase land reform farmers’ productivity. The study concluded that training is paramount to farmers’ development and further recommends more research undertakings.

Vegetation survey of the Khomas Hochland in central-western Namibia: syntaxonomical descriptions

Background: The Great Escarpment of southern Africa takes the form of an extended mountainous highland in central-western Namibia, commonly referred to as the ‘Khomas Hochland’. It is regarded as an area of high botanical diversity. Yet only few localised studies on the vegetation composition are available. The Khomas Hochland is formed on the southern part of the Damara Orogen and dominated by metamorphosed sediments. Climatically it forms a transition between the hot desert of the Namib and the slightly cooler hot steppe in the inland.Objectives: To classify and provide syntaxonomical descriptions of the vegetation of the Khomas Hochland.Methods: A dataset comprising 1151 relevés and 914 species was compiled from various surveys, mostly collected under, and to the standards of, the umbrella project ‘Vegetation Survey of Namibia’. For first classifications, the data set was reduced to a synusial set consisting of trees, shrubs, dwarf shrubs and grasses only.Results: The classification resulted in four major landscape units, being the Pre-Namib and Escarpment zone, the Khomas Hochland proper, riverine habitats as well as surrounding lowlands. The classification was further refined using Cocktail procedures to produce 30 associations, one with four sub-associations. These are described in this paper.Conclusion: A classification of synoptic data grouped the associations into five orders and one undefined cluster of associations on specialised desert habitats. Four of these orders correspond to the habitat types identified in the first classification. The fifth order, the Senegalio hereroensis–Tarchonanthoetalia camphorathi, represents high mountains of the central Khomas Hochland, which link biogeographically to the grassland biome in South Africa.

Identifying potential protected areas in the Grassland Biome of South Africa

South Africa is considered to be one of the most biologically diverse countries in the world. The conversion, degradation, and fragmentation of natural habitats have caused a loss of biodiversity in many areas. Grasslands have been widely recognised as important for both biodiversity and economic development. Many conservation efforts have in the past been theory driven, without actionable, feasible results. We hypothesised that correct implementation of the available data will indicate where conservation efforts should be focused to move closer to achieving targets for biodiversity conservation in the Grassland Biome in South Africa. We identified an area (near Heilbron and Petrus Steyn in the Free State) that is representative of the biodiversity in the region and is suitable for modern conservation efforts in the ‘real world’. This approach provides a practical look at conservation in the modern era and a feasible result for conservation efforts.

Spatial and Temporal Changes in the Normalized Difference Vegetation Index and Their Driving Factors in the Desert/Grassland Biome Transition Zone of the Sahel Region of Africa

The ecological system of the desert/grassland biome transition zone is fragile and extremely sensitive to climate change and human activities. Analyzing the relationships between vegetation, climate factors (precipitation and temperature), and human activities in this zone can inform us about vegetation succession rules and driving mechanisms. Here, we used Landsat series images to study changes in the normalized difference vegetation index (NDVI) over this zone in the Sahel region of Africa. We selected 6315 sampling points for machine-learning training, across four types: desert, desert/grassland biome transition zone, grassland, and water bodies. We then extracted the range of the desert/grassland biome transition zone using the random forest method. We used Global Inventory Monitoring and Modelling Studies (GIMMS) data and the fifth-generation atmospheric reanalysis of the European Centre for Medium-Range Weather Forecasts (ERA5) meteorological assimilation data to explore the spatiotemporal characteristics of NDVI and climatic factors (temperature and precipitation). We used the multiple regression residual method to analyze the contributions of human activities and climate change to NDVI. The cellular automation (CA)-Markov model was used to predict the spatial position of the desert/grassland biome transition zone. From 1982 to 2015, the NDVI and temperature increased; no distinct trend was found for precipitation. The climate change and NDVI change trends both showed spatial stratified heterogeneity. Temperature and precipitation had a significant impact on NDVI in the desert/grassland biome transition zone; precipitation and NDVI were positively correlated, and temperature and NDVI were negatively correlated. Both human activities and climate factors influenced vegetation changes. The contribution rates of human activities and climate factors to the increase in vegetation were 97.7% and 48.1%, respectively. Human activities and climate factors together contributed 47.5% to this increase. The CA-Markov model predicted that the area of the desert/grassland biome transition zone in the Sahel region will expand northward and southward in the next 30 years.

Genetic diversity of the Fusarium oxysporum complex isolated from the grassland biome of South Africa.

The genetic diversity of pathogenic members of the Fusarium oxysporum species complex (FOSC) has been intensively studied worldwide, yet strains occurring from native soils with low anthropogenic disturbance remain poorly understood. This study focused on 355 F. oxysporum isolates from soils with low anthropogenic activity obtained from the grassland biome of South Africa. Analysis of the translation elongation factor 1-alpha (tef-1α) gene revealed high levels of sequence type (ST) diversity within the soil population in comparison to the global dataset. Phylogenetic relationships of the South African isolates revealed that only four nested within FOSC Clade 1. This is the first report of members of the basal clade recovered from ecosystems with low anthropogenic disturbance from Sub-Saharan Africa. The remaining strains nested within Clades 2 to 5. This study contributes significantly to our understanding of the distribution of the FOSC in natural systems as we show that FOSC populations in the South African grassland biome are genetically diverse. This fills in our knowledge gap as previous studies reported only on the occurrence and diversity of the FOSC isolated from plant debris in South Africa. This is the first comprehensive survey of fusaria from grassland soils with low anthropogenic disturbance in South Africa.

Diversity patterns of plants and arthropods in soybean agro-ecosystems in the Grassland Biome of South Africa

Janse van Rensburg PD, Siebert SJ, Masehela T, Ellis S, Van den Berg J. 2020. Diversity patterns of plants and arthropods in soybean agroecosystems in the grassland biome of South Africa. Biodiversitas 21: 5559-5570. Soybean is widely cultivated in the grassland biome of South Africa (ca. 800 000 ha per annum). Yet the possible effects that large-scale cultivation of soybean has on biodiversity in adjacent habitat are not fully understood. This study aimed to describe the plant and arthropod species assemblages and diversity patterns within these soybean agroecosystems. Surveys were conducted inside soybean fields, field boundaries (transition zones between soybean fields and adjacent habitat), and adjacent pasture. An adapted D-vac was used to sample arthropods in the different zones, while plant surveys were conducted by means of fixed width (2 m) line transect. A total of 320 plant species (4910 specimens) and 373 arthropod morpho-species (9216 specimens) were recorded. Soybean fields had significantly lower plant and arthropod diversity than the adjacent habitats. Plant species diversity was similar in the field boundary and adjacent pasture. Significantly higher species richness and abundance of arthropods were found in the boundary than the pasture. These results show that the cultivation of soybean and the associated agricultural practices had no adverse effects on biodiversity patterns in the adjacent habitats. However, the boundary dominated by alien plant species did contain a significantly different plant species composition from the pasture. This difference was also mirrored by unique assemblages of arthropods. This suggests that disturbance resulting from soybean cultivation contributed to species losses and gains that maintained diversity in the field boundary but changed its plant and arthropod species composition. No effect was found in the pasture beyond the boundary (> 50 m). High diversity, but unique species assemblages of plants and arthropods in the boundary and pasture suggest that these habitats may have important conservation value in soybean agroecosystems by supporting ecosystem functions and services.