Acacia Karroo Research Articles

Reconstructing thicket clump formation using association rules analysis

AbstractAimVegetation change such as woody encroachment is characterised by changing species interactions, and processes such as competition and facilitation may be inferred from patterns of association between juveniles and mature individuals of different species. Our aim was to apply and evaluate association rules analysis (ARA), a rule‐based data‐mining technique more commonly known as market basket analysis, as a novel tool to examine the associations between woody species in different demographic stages along a thicket encroachment gradient.LocationThe research was conducted in a subtropical thicket–savanna mosaic (730 mm mean annual rainfall) in the Eastern Cape, South Africa.MethodsWe used a space‐for‐time substitution approach and sampled woody plants in different size classes at sites representing early, intermediate and late stages of encroachment. All individuals were recorded as occurring singly or in unique clumps. We used ARA to determine which associations between species in different size classes were common overall, and more common than expected, at each of the three encroachment stages.ResultsThe most important association rules indicated that Vachellia karroo recruited singly and in large numbers in open grassland and, once mature, provided nucleation sites for a small suite of species dominated by Scutia myrtina. In the later stages, multiple diverse associations were found in increasingly large clumps.ConclusionsOur sampling approach and ARA proved useful for characterising common species‐size class associations, illuminating changing species interactions and recruitment patterns along a thicket clump formation sequence. In studies of vegetation change, ARA can complement multivariate analyses of species composition to reveal specific associations, and it can provide a less laborious alternative to point‐pattern analysis for elucidating spatial associations.

Evaluation of Acacia karroo’s Potential Aspect in the Phytoremediation of Soil Pollution

The rise in contaminated sites presents a significant issue for the environment and human health, necessitating the decontamination of the surroundings and the adoption of effective decontamination strategies. This investigation was initiated to assess the potential aspects of Acacia karroo in conjunction with enzyme activity, a method that shows promise for mitigating soil contamination. Acacia karroo, with its hyperaccumulator traits, demonstrates great capacity. Enzymes significantly efficiently convert and detoxify harmful substances to a non-toxic level. ICP-MS quantified the concentrations of trace elements in Acacia karroo, while colorimetric assays were used to determine the activity levels of the enzymes. Ten toxic elements were identified in leaf samples of Acacia karroo in the following sequence: Sr > Zn > Cr > V > Rb > Cu > Ni > Y > Sc > Co; concentrations ranged between 203.86 ± 4.48 ppm (Zn) and 10.12 ± 0.09 ppm (Sc). The concentration of these metals was very high, posing a potential risk of harming the environment. Meanwhile, the three identified enzymes, invertase (INV), phosphatase (PHO), and catalase (CAT), have high and average activity levels, respectively. PHO and CAT showed a positive correlation with Zn, Rb, Sr, and Y, while INV correlated positively with Sc, V, Cr, Co, Cu, and Ni content. The principal component analysis (PCA) findings in this study demonstrated an inconclusive correlation between soil enzyme activity and soil heavy metal content. Both positive and negative correlations between soil enzyme activity and heavy metals were observed. This investigation revealed Acacia karroo as an optimal botanical species for phytoremediation. Consequently, a correlation analysis demonstrated that incorporating the Acacia karroo species along with enzyme activity seems to be a highly promising environmentally friendly technique for remediating soil pollution. The Acacia species can also be used in phytoremediation efforts to help conserve biodiversity. Subsequent investigations should focus on the operational mechanisms of different plant parts used as herbal remedies, isolated compounds, their efficacy, adverse effects, and practical implications.

Spatial distribution of woody plants in relation to mistletoe-infected Vachellia karroo trees in a semi-arid African savanna

By increasing resource heterogeneity, mistletoe-infected trees can restructure plant community processes and distribution patterns. No information is available on how mistletoe-infected Vachellia (Acacia) karroo trees within V. karroo dominated stands are spatially distributed, and on how they influence the spatial patterns of their surrounding conspecifics and heterospecifics. Each woody plant was stem mapped using a cartesian plane (x, y) within three 50×50 m plots located in V. karroo dominated stands in a semi-arid savanna, South West Zimbabwe. Pair correlations g(r) were used for the univariate analysis and Poisson process null models were applied to quantify and detect overall departure from randomness. For the bivariate analysis, pair correlations g12(r) under the null model of independence were used, whilst the mark correlation function (kmm(r)) was used to analyse the correlation of tree canopy area and mistletoe infection intensity. For each plot, size class distributions, based on tree height and basal stem diameter displayed negative J curves, with steep negative regression slopes across the size classes, clearly indicating a strongly recruiting population of V. karroo. The univariate patterns of all trees (infected and non-infected) were consistent with a random pattern, which is attributed to unsystematic mistletoe seed dispersal by birds. The univariate analysis of all woody plants (adults and juveniles) exhibited aggregation at small spatial scales due to the high abundance of clustered seedlings and saplings. At small spatial scales, understory woody plants (both conspecifics and non-conspecifics) were positively associated with mistletoe-infected trees due to mistletoephily which is the facilitation (or nurse protégé interactions) within the more resource-rich mistletoe-infected tree subcanopies. These results provide strong evidence suggesting that the variations in spatial pattern modification by mistletoe-infected trees could further increase spatial heterogeneity in this semi-arid savanna. As such, by increasing heterogeneity, mistletoe-infected trees can increase the resilience of semi-arid savannas in the face of perturbations and stochastic events.

South African Medicinal Plants Used in the Treatment of Human Bacterial Infections: An updated Review

Traditional medicine based on the use of medicinal plants plays an important role in the preservation of health and well-being of many people globally. Today herbal medicine application is progressively finding more significance especially with the acknowledgement of the challenges of antibiotic resistance. The aim of this review was to collect literature based on the traditional application of South African medicinal plant species used in South Africa to prevent and treat various pathogenic bacterial infections. The search was carried out using key electronic scientific databases including PubMed, Google Scholar, SpringerLink, ProQuest, Science Direct, Elsevier, BioMed Central. Other sources of literature included scientific articles, book chapters, dissertations, theses and websites. It was found that Bacillus spp., Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were the most frequently investigated bacterial pathogens which have developed resistance to most of the available standard antibiotics. Organic and aqueous extracts of many South African plants including Acacia karroo, Psidium guajava, Punica granatum, Eucomis autumnalis, Vernonia amygdalina and Cyathula uncinulata have demonstrated potent antibacterial efficacy against the aforementioned pathogens. This review exemplifies that South African medicinal plants have the potential to be considered as new leads for the development of antibacterial agents against resistant pathogens.

Effect of Vachellia karroo leaf meal inclusion levels on growth, meat pH, shear force, cooking loss and shelf life of Ross 308 broiler chickens

Effect of <i>Vachellia karroo</i> leaf meal inclusion levels on growth, meat pH, shear force, cooking loss and shelf life of Ross 308 broiler chickens

Effect of harvesting site on mineral concentration of browse species found in semi-arid areas of South Africa

The objective of this study was to investigate the effect of the harvesting site on the mineral concentration of selected browse species found in semi-arid areas of South Africa (North West and Limpopo province sites). Five trees from each of the 52 woody browse species were randomly identified and harvested in the North West and Limpopo provinces, South Africa, dried and ground for laboratory analysis. One-way ANOVA was used to analyse the mineral composition of browse species that were not common in both harvesting sites, while a two-way factorial design within a completely randomized experimental design was used to analyse the mineral composition of browse species that were common in both harvesting sites. MANOVA tests were also used in order to assess the species and harvesting site effects on mineral concentrations of species common in both sites. Through ANOVA and MANOVA, there were significant species, harvesting site, and species × harvesting stage effects on all the measured parameters (both macro and micro mineral elements). Phosphorus and calcium concentrations were the highest in Adansonia digitata species, whereas the lowest was obtained in Androstachys jonhsonii browse species in the Limpopo harvesting site. Within each province, Schinus molle found in the North West site had the highest phosphorus, potassium and sodium values when compared to all species within the same province. Vachellia nilotica subsp. kraussiana , M. azedarach and Ziziphus mucronata found in Limpopo province had the highest level of magnesium when compared to other species found within the same province. Senegalia caffra , Grewia flava , Vachellia karroo , Vachellia nilotica subsp. kraussiana , Searsia leptodictya and Melia azedarach found in the Limpopo province had the highest phosphorus level when compared to the same species found in the North West province. Senegalia caffra , Peltophorum africanum , Grewia flava , Vachellia hebeclada and Terminalia sericea found in the North West province had the highest iron levels when compared to the same species found in Limpopo province. There is a need to provide supplementation to those animals exposed to species that have a lower concentration of certain elements.

Performance of goats browsing on Vachellia karroo encroached communal lands and open grasslands in the Eastern Cape province, South Africa

The objective of this study was to evaluate the effects of season, rangeland type, and herd size on the performance of goat browsing. A total of eighty communal household goat herds from Mbashe and Nkonkobe municipalities were monitored for twelve months. The effect of season, rangeland type and herd size on average daily gain (ADG), body condition score (BCS), body weight (BW), births, purchases, sales, deaths, goat production potential (GPP) and goat production efficiency (GPE) were evaluated. The Mbashe community was regarded to represent open grassland, while the Nkonkobe community represented the Vachellia karroo encroached rangeland. Approximately 1 560 goats of all classes were monitored. Results showed that more entries, births and sales, but fewer deaths, were recorded in V. karroo encroached rangeland than open grassland for larger herds (p < 0.05). The GPP and GPE were higher in V. karroo encroached rangeland than open grassland for larger than smaller herds (p < 0.05). Goat population dynamics, BW for castrates, sales and GPE were significantly higher among seasons (p < 0.05). It was concluded that larger herds of goats browsing V. karroo performed better in comparison to those that grazed open grasslands, which demonstrates that bush encroachment can benefit goat farming.

Participatory inventory and nutritional evaluation of local forage resources for smallholder free-range beef production in semi-arid areas of South Africa

Feed scarcity is a major challenge facing free-range beef farming in semi-arid areas. Specifically, low quality and quantity of forage in rangelands and higher feeding costs are the main constraints limiting smallholder free-range beef farmers’ participation in mainstream beef markets. Using farmers’ participatory approaches, this study identified major locally available forage resources (LAFRs) and evaluated their nutritional value. A total of 40 free-ranging commercially orientated smallholder beef farmers were interviewed using semi-structured questionnaires and tasked to identify LAFRs in the Cradock and Middelburg areas of the Eastern Cape, South Africa. Chemical analysis was conducted for the most cited forages such as African sheepbush (Pentzia incana), sweet thorn (Vachellia karroo) leaves and pods, reed (Phragmites australis), lucerne (Medicago sativa) hay, natural pasture grasses (NPGs) and barbary fig, or prickly pear cactus, (Opuntia ficus-indica) cladodes collected from twelve participants’ farms. Feed shortage was ranked by more than 53% respondents as the main constraint to smallholder beef production. Regardless of the farming area, crude protein content of V. karroo leaves and pods averaging 18.8 and 19.5%, respectively, was higher than other LAFRs. However, V. karoo pods had relatively low ash content than other forages in both farming areas. Opuntia ficus-indica attained high in vitro neutral detergent fibre digestibility at 12, 24 and 48 hr incubation periods, due to low neutral detergent fibre, acid detergent fibre and acid detergent lignin. Integration of participatory inventory and chemical analysis proved to be reliable in identifying LAFRs, with V. karroo leaves and O. ficus-indica cladodes being the main potential forage resources for inclusion in beef cattle diets. Further research is recommended to substantiate their supplementary nutritive value and level of inclusion in beef cattle finishing diets.

CO2‐fertilisation enhances resilience to browsing in the recruitment phase of an encroaching savanna tree

Abstract CO2‐fertilisation is implicated in the widespread and significant woody encroachment of savannas due to CO2‐stimulated increases in below‐ground reserves that enhance sapling regrowth after fire. However, the effect of CO2 concentration ([CO2]) on tree responses to the other major disturbance in savannas, herbivory, is poorly understood. Herbivory responses cannot be predicted from fire responses, as herbivore effects occur earlier during establishment and are moderated by plant palatability and defence rather than below‐ground carbon accumulation. The relationship between herbivory and [CO2] is explored here using a widespread, strongly encroaching savanna tree, Vachellia karroo. Using greenhouse‐grown seedlings under past—through to predicted future—[CO2] (180–1000 ppm) and field‐grown seedlings under ambient [CO2], we assessed plant survival, growth, defence and palatability. Increasing [CO2] improves the tolerance of greenhouse‐grown seedlings to herbivory by stimulating growth and allowing a critical size threshold associated with survival to be reached earlier, thereby decreasing the probability of fatal herbivory during the vulnerable recruitment phase. Elevated [CO2] also decreases the time taken to reach a second size threshold linked to accelerated recovery of field‐grown seedlings following herbivory. Seedling growth responses to increasing [CO2] are nonlinear, suggesting that historic growth and survival enhancements are smaller than those predicted for the future. Increasing [CO2] is associated with greater resistance to herbivores (more branched shoot architecture) but not leaf palatability (C:N ratio) or defence (leaf tannins and spine density). Increasing V. karroo densities already constitute a major land management problem in southern African savannas. However, encroachment by this species, and likely other savanna tree species, may be greatly exacerbated under future [CO2], as tolerance to herbivory at the recruitment stage is further enhanced. Read the free Plain Language Summary for this article on the Journal blog.

Using pollution indices to develop a risk classification tool for gold mining contaminated soils

The presence of potentially toxic elements (PTEs) in soil and plants is a risk factor to human well-being and the environment. Soil and leaves from a traditional medicinal plant, Vachellia karroo, known as the sweet thorn plant, were assessed to determine the extent of pollution by PTEs from gold mine tailings in a case study area of Matjhabeng Local Municipality, South Africa. A risk classification tool was developed using the different indicators of pollution quantified to describe the pollution risk at each sampling site. High concentrations of copper, cadmium, lead, nickel, and zinc were measured in the soil, which exceeded the maximum permissible soil quality limits. The enrichment factor and geoaccumulation index results also confirmed heavy soil pollution by copper, nickel, and zinc, with exceptionally heavy pollution by cadmium and selenium. The PTEs in the soil were in an exchangeable form, with the sweet thorn plant accumulating lead and selenium at toxic levels, which poses a risk to the health of the local people as the plant is used for medicinal purposes. The overall pollution risk classification tool of the sampling sites showed that 17% were high-risk areas, 53% were moderate-risk areas, and 20% of the sites were low-risk areas.

Cowpea Growth and Nitrogen Fixation Performance under Different Mulch Treatments

Mulching is regarded as the most important of the three conservation agriculture principles in increasing crop yield in the short term. Thus, the main objective of this study was to investigate the impact of mulch type and mulch application rate on biological nitrogen fixation (BNF), physiological and yield responses of cowpea. A multi-locational (two locations) and multi-seasonal (two seasons) study was carried out under rainfed conditions in the Limpopo Province of South Africa. Three mulch types (Moringa oleifera stems; Moringa oleifera leaves and twigs; and Vachellia karroo leaves and stems) were uniformly spread on the surface at four rates (0, 3, 6, 9 t/ha). The application of mulches, regardless of the rate and type, improved cowpea chlorophyll content and agronomic parameters, such as stem diameter and plant height. Grain yield at Syferkuil responded to the mulching effect in both seasons, while at Ofcolaco, differences were only observed in one of the seasons. Cowpea under control discriminated against 15N more than under mulched treatments, resulting in more than 70% of the nitrogen being derived from air compared to 50% in mulched plots. This study demonstrated that organic surface mulches improved the physiological responses of cowpea and that organic surface mulches with a lower C:N ratio significantly reduced BNF.

Traditional uses of wild and tended plants in maintaining ecosystem services in agricultural landscapes of the Eastern Cape Province in South Africa

BackgroundMany communities in developing countries rely on ecosystem services (ESs) associated with wild and cultivated plant species. Plant resources provide numerous ESs and goods that support human well-being and survival. The aim of this study was to identify and characterize wild and tended plant species, and also investigate how local communities in the Eastern Cape Province in South Africa perceive ESs associated with plant resources.MethodsThe study was conducted in six local municipalities in the Eastern Cape Province, between March 2016 and September 2021. Data on socio-economic characteristics of the participants, useful plants harvested from the wild and managed in home gardens were documented by means of questionnaires, observation and guided field walks with 196 participants. The ESs were identified using a free listing technique.ResultsA total of 163 plant species were recorded which provided 26 cultural, regulating and provisioning ESs. Provisioning ESs were the most cited with at least 25 plant species contributing towards generation of cash income, food, traditional and ethnoveterinary medicines. Important species recorded in this study with relative frequency of citation (RFC) values > 0.3 included Alepidea amatymbica, Allium cepa, Aloe ferox, Artemisia afra, Brassica oleracea, Capsicum annuum, Cucurbita moschata, Hypoxis hemerocallidea, Opuntia ficus-indica, Spinacia oleracea, Vachellia karroo and Zea mays.ConclusionResults of this study highlight the importance of plant resources to the well-being of local communities in the Eastern Cape within the context of provision of essential direct and indirect ESs such as food, medicinal products, construction materials, fodder, regulating, supporting and cultural services. The ESs are the basis for subsistence livelihoods in rural areas, particularly in developing countries such as South Africa. Therefore, such body of knowledge can be used as baseline data for provision of local support for natural resource management initiatives in the province and other areas of the country.

CO2‐stimulation of savanna tree seedling growth depends on interactions with local drivers

Abstract Woody encroachment in southern African savanna has been partly attributed to rising atmospheric [CO2] fertilising the growth of C3 trees but less so that of competing C4 grasses. However, growth conditions (resource availability, competition, rooting space and herbivory) must be suitable for the effects of elevated CO2 (eCO2) to be realised. This research investigated the interactions between the positive effect of eCO2 on tree seedling growth and limitations imposed by drought, herbivory and competition with C4 grasses. Seedlings of the prolific encroaching C3 tree Vachellia karroo were grown at ambient (400 ppm) or eCO2 (800 ppm) in Open‐Top Chambers and exposed to a variety of stresses typical of savanna systems. Photosynthetic, growth and allocation responses to eCO2 and other treatments were determined. Unsurprisingly, we show strong growth and water‐saving responses of V. karroo seedlings to eCO2 when in the absence of competition and herbivory. However, the addition of either grass competition or simulated herbivory in the first season of growth significantly moderated this stimulation, while neither drought nor shading diminished the eCO2 effect relative to similarly treated plants grown at ambient [CO2]. Synthesis. We demonstrate that eCO2‐induced C3 stimulation in encroaching savanna species such as V. karroo will be inconsistent across time and space. This research does not detract from the suggestion that increasing atmospheric CO2 is implicated in woody encroachment, but rather that eCO2 benefits to C3 tree seedlings are only realised when growth conditions are suitable. Inconsistencies in eCO2 response will translate into spatial and temporal variation in seedling responses to eCO2 and CO2‐driven woody encroachment, explaining some of the variability observed in woody encroachment across geographical regions and resource and herbivore gradients.

Delineation of Paraburkholderia tuberum sensu stricto and description of Paraburkholderia podalyriae sp. nov. nodulating the South African legume Podalyria calyptrata

Since the discovery of Paraburkholderia tuberum, an indigenous South African species and one of the first beta-rhizobia described, several other South African rhizobial Paraburkholderia species have been recognized. Here, we investigate the taxonomic status of 31 rhizobial isolates from the root nodules of diverse South African legume hosts in the Core Cape Subregion, which were initially identified as P. tuberum. These isolates originate from the root nodules of genera in the Papilionoideae as well as Vachellia karroo, from the subfamily Caesalpinioideae. Genealogical concordance analysis of five loci allowed delineation of the isolates into two putative species clusters (A and B). Cluster A included P. tuberum STM678T, suggesting that this monophyletic group represents P. tuberum sensu stricto. Cluster B grouped sister to P. tuberum and included isolates from the Paarl Rock Nature Reserve in the Western Cape Province. Average Nucleotide Identity (ANI) analysis further confirmed that isolates of Cluster A shared high genome similarity with P. tuberum STM678T compared to Cluster B and other Paraburkholderia species. The members of Cluster B associated with a single species of Podalyria, P. calyptrata. For this new taxon we accordingly propose the name Paraburkholderia podalyriae sp. nov., with the type strain WC7.3bT (= LMG 31413T; SARCC 750T). Based on our nodA and nifH phylogenies, P. podalyriae sp. nov. and strains of P. tuberum sensu stricto (including one from V. karroo) belong to symbiovar africana, the symbiotic loci of which have a separate evolutionary origin to those of Central and South American Paraburkholderia strains.

English

South African indigenous plants have been predominantly studied for their antibacterial abilities, overlooking their antipathogenic and antivirulence (also known as antiquorum sensing) potential. Hence, this study explored the selected medicinal plants as possible agents capable of interfering with bacterial growth, quorum sensing and biofilm formation and identified their respective bioactive compounds. Ten medicinal plants were extracted with varied solvents. Melianthus comosus (dichloromethane, aqueous and methanol), Pelargonium sidoides (aqueous) and Vachellia karroo (aqueous and methanol) extracts showed potent minimum inhibitory concentration values ranging from 0.19 to 0.78 mg/ml against the tested bacterial pathogens: Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pyogenes, and Escherichia coli. Reduced violacein production (up to 38.34%) in Chromobacterium violaceum was noted for Melianthus comosus, Plectranthus ecklonii and Pelargonium sidoides extracts. Treatment of five MDR bacterial pathogens with active extracts for anti-adhesion and biofilm development showed up to 66.34 and 31.82% inhibitory effects, respectively. Chemical characterization of active extracts revealed compounds such as &alpha;-D-glucopyranoside, methyl, linalool, octadecanoic acid and hexadecanoic acid. The biological assays validated the tested plant extracts as having antibacterial and antipathogenic potentials that could be used against multidrug resistant bacteria. Key words: Antibacterial activity, biofilm inhibition, chemical characterization, multidrug resistance, phytochemicals, quorum sensing inhibition.

Reinvasion of Native Invasive Trees After a Tree-Thinning Experiment in an African Savanna

Woody plant encroachment has serious negative consequences for ranchers because of the reduction in herbaceous fodder for domestic livestock. A long-term monitoring of a tree-thinning experiment was established near Magudu (northern KwaZulu-Natal, South Africa) in 1990. The objective of this experiment was to determine the optimal tree density that would maximize grass production while benefiting grasses from nitrogen fixation, hydraulic lift, and/or shade from the leguminous trees. The initial dominant species was the nitrogen-fixing tree, Dichrostachys cinerea. There were 12 plots (6 pairs) with trees removed to approximate 0, 179, 277, 428, and 625 trees ha−1, with 1 pair left as a control (unmanipulated). One plot of each replicate (except the controls) was treated with short-acting herbicide (picloram) once in 1990. We collected data on herbaceous cover and species composition, tree species composition, sizes, and mortality. We also used remote sensing to examine the patterns of herbaceous cover. Herbaceous biomass decreased as tree density increased. After 30 yr, the same dominant tree species (D. cinerea) had reinvaded all the removal plots despite the fact that several encroaching species (Vachellia karroo, V. tortilis, V. nilotica) occurred in these plots. These D. cinerea trees were mostly less dense and contained many more juvenile individuals in the cleared and partially cleared plots than those in the control plots after 30 yr. Should maximizing herbaceous cover be the goal, repeated brush management would be necessary to maintain adequate control of woody plants in these savannas.

Spectral classification, mapping and physical habitat implications of a riparian invasion by Tamarix ramosissima Ledeb. in the Touws River, Klein Karoo, South Africa

This paper investigates the invasion of a reach of the Touws River by the deciduous alien tree Tamarix ramosissima Ledeb. (Pink Tamarisk, Saltcedar). The objectives of the paper were to investigate the utility of a delta-normalised difference vegetation index (dNDVI) in evaluating the status, pattern and process of invasion, and to evaluate the implications of the invasion for riverscape morphodynamics and physical habitat structure and function. The spectral classification developed had an overall accuracy of 59.89%, omission error of 28.25%, and commission error of 11.86%. The classification of vegetation was used to quantify the aerial extent and pattern of invasion (currently at least 65.50% of the valley floor vegetation cover). Field observations and existing knowledge of seed dispersal mechanisms and germination constraints of the invasive tree were compared with those of the indigenous sweet thorn Vachellia karroo, to provide insight into invasion patterns and processes within the reach. The linear channel-flanking distribution of the invasion has the potential to alter reach hydrology and morphodynamics, which are key building blocks of physical habitat structure and function. The spectral classification approach demonstrated is relatively simple, has a strong biophysical basis in that it exploits a known, predictable and observable seasonal vegetation response that produces a clear spectral signature, and can be applied to long reaches of rivers impacted by alien vegetation invasions.

Rhizosphere Diazotrophs and Other Bacteria Associated with Native and Encroaching Legumes in the Succulent Karoo Biome in South Africa.

Total and diazotrophic bacteria were assessed in the rhizosphere soils of native and encroaching legumes growing in the Succulent Karoo Biome (SKB), South Africa. These were Calobota sericea, Lessertia diffusa, Vachellia karroo, and Wiborgia monoptera, of Fabaceae family near Springbok (Northern Cape Province) and neighboring refugia of the Fynbos biome for C. sericea for comparison purposes. Metabarcoding approach using 16S rRNA gene revealed Actinobacteria (26.7%), Proteobacteria (23.6%), Planctomycetes, and Acidobacteria (10%), while the nifH gene revealed Proteobacteria (70.3%) and Cyanobacteria (29.5%) of the total sequences recovered as the dominant phyla. Some of the diazotrophs measured were assigned to families; Phyllobacteriaceae (39%) and Nostocaceae (24.4%) (all legumes), Rhodospirillaceae (7.9%), Bradyrhizobiaceae (4.6%) and Methylobacteriaceae (3%) (C. sericea, V. karroo, W. monoptera), Rhizobiaceae (4.2%; C. sericea, L. diffusa, V. Karroo), Microchaetaceae (4%; W. monoptera, V. karroo), Scytonemataceae (3.1%; L. diffusa, W. monoptera), and Pseudomonadaceae (2.7%; V. karroo) of the total sequences recovered. These families have the potential to fix the atmospheric nitrogen. While some diazotrophs were specific or shared across several legumes, a member of Mesorhizobium species was common in all rhizosphere soils considered. V. karroo had statistically significantly higher Alpha and distinct Beta-diversity values, than other legumes, supporting its influence on soil microbes. Overall, this work showed diverse bacteria that support plant life in harsh environments such as the SKB, and shows how they are influenced by legumes.

Commercialization Potential of Six Selected Medicinal Plants Commonly Used for Childhood Diseases in South Africa: A Review

Globally, the potential of medicinal plants is increasingly being recognized due to their relative availability, particularly in rural areas. This review explored the ethnobotanical and economic values of six selected medicinal plants widely used to treat and manage childhood diseases in South Africa. Acalypha glabrata, Aloe maculata, Datura stramonium, Gomphocarpus fruticosus, Rhoicissus tridentata and Vachellia karroo were selected based on their high relative frequency of citations for treating a wide range of diseases. Information was obtained from various scientific databases and ethnobotanical books. In addition to being popular for treating childhood diseases, the selected medicinal plants possess diverse applications in traditional medicine for other age groups, highlighting their general therapeutic values. This translates to extensive harvesting, trading and consumption of these plants in order to meet demands on local levels. Currently, empirical data on the economic value of the selected plants remain poorly reported. Even though South Africa has many laws to conserve and promote indigenous knowledge and medicinal plants, their commercialization remains low. Particularly the cultivation of the selected plants needs to be promoted under a participatory management action plan to stimulate the economy of the disadvantaged. A collaborative research framework for the inclusive transformation of indigenous medicinal plants is recommended to reveal their concealed beneficial properties.

Acacia Karroo Pods and Leaves as Major Feed for Fattening of Goats

The objective of this study was to assess the effects of using Acacia karroo pods and leaves for fattening of goats. The experiment was carried out at a farm in Mashava, an area located in Masvingo Province within latitude 20° 2´ 43˝ S and longitude 30° 40´ 29˝ E in the south-eastern part of Zimbabwe. Mixed dried leaves and pods of Acacia karroo were ground using a 2 mm screen and then included at levels of 0, 20, 60 and 100%, replacing ground maize in the diets. Weaned goats (n=64) were allocated in weight order to groups of four animals and randomly assigned to the four treatments in a randomised block design. Growth rates of goats fed with diet containing 100% A. karroo had higher (15.48 ±0.069 kg) final weight compared to any other diets followed with goats fed diet containing 60% of A. karroo and results showed significant differences (p&amp;lt;0.001) between treatments. Feed intake over all treatments was comparable with around 500 g day-1. Goats fed with control diet recorded highest voluntary feed intake of 504.5 g day-1 and lowest of 499 g/day was recorded from diet containing 60 % A. karroo. Goats which were fed with 60 % and 100% A. karroo had low feed conversion ratio (FCR) although the results show significant differences (p&amp;lt;0.05) among all treatments. Goats fed diets containing 0% A. karroo had the least average weekly weights as compared to all other diets. Average weekly weight gains for goats fed with 60 % A. karroo and 100% A. karroo diets rapidly increased in week 2 with those fed 100% A. karroo diets recorded a highest gain of 915.75 ±59.888 g and results were significantly different (p&amp;lt;0.001) between treatments. Farmers are recommended to use 60-100% A. karroo diets when pen fattening goats.