Searsia Lancea Research Articles

Nutraceutical and Ethnopharmacological Properties of Searsia lancea (L.f.) F.A.Barkley (Family Anacardiaceae): A Narrative Review.

<i>Searsia lancea </i>(L.f.) F.A.Barkley is an evergreen tree well-known for its edible fruits and is also widely used in traditional medicine. The current study was aimed at documenting medicinal and traditional uses of <i>S. lancea</i> and its phytochemical and pharmacological properties. Research articles on nutraceutical and ethnopharmacological properties of <i>S. lancea</i> were searched from online databases such as PubMed<sup>®</sup>, Web of Science, SciELO, Google Scholar, ScienceDirect<sup>®</sup>, SpringerLink<sup>®</sup> and Scopus<sup>®</sup> and also pre-electronic literature obtained from the university library. <i>Searsia lancea</i> is used as ethnoveterinary medicine and as traditional medicine for fever, measles, sores, wounds, diabetes, sexually transmitted infections, gastrointestinal problems and skin and respiratory infections. Chemical compounds identified from <i>S. lancea</i> include alcohol, alkane, amide, flavonoids, naphthalene, alkaloids, terpenoids, phenols, tannins, steroids, anthraquinones and volatile compounds. <i>Searsia lancea </i>crude extracts demonstrated anthelmintic, antibacterial, antimycobacterial, antifungal, anticancer, anticholinesterase (AChE), anti-inflammatory, antioxidant, cytotoxicity and nematicidal activities. This review highlights the need for detailed nutraceutical and ethnopharmacological studies of <i>S. lancea</i> focusing on its nutritional, phytochemical, biological and toxicological properties, <i>in vivo</i> and clinical studies.

Antifungal and antioxidant properties of medicinal plants used against fungal infections

Background: Antioxidants present in plant extracts prevent free radicals from causing chronic diseases in humans.Aim: The study investigated 12 medicinal plants (Kleinia longiflora DC., Berchemia discolor [Klotzsch] Hemsl., Persea americana Mill., Sansevieria hyacinthoides [L.] Druce, Dichrostachys cinerea [L.] Wright Arn, Withania somnifera Dunal [Ashgandh], Momordica balsamina L., Lonchocarpus capassa, Pappea capensis, ‘Rhus lancea L. fil’ with ‘Searsia lancea (L.F.) F.A. Barkley’ Peltophorum africanum, Maytenus heterophylla [Eckl. Zeyh.] Robson) for antioxidant activity using the qualitative and quantitative 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay.Setting: The plant species were selected from the ethnomedicinal plant database of over 300 medicinal plants used for therapeutic purposes in Limpopo province.Methods: The plant materials were extracted with solvents of various polarities such as acetone, dichloromethane (DCM), methanol, hexane, and water. The qualitative and quantitative DPPH methods were used to determine the antioxidant activities of plant extracts.Results: The yellow bands revealed the presence of antioxidant compounds against the purple background on the Thin Layer Chromatography (TLC) plates. Methanol, hexane, and water extracts of L. capassa were the most active radical scavengers in the DPPH assay among the six medicinal plants screened. Plant extracts of P. africanum showed strong antioxidant activity by inhibiting DPPH, compared with the standard ascorbic acid.Conclusion: The findings indicate that some extracts can be used as an easily accessible source of natural antioxidants.Contribution: The findings revealed that the plant species investigated displayed noteworthy antioxidant activity, which provides scientific evidence for their utilisation by traditional health practitioners to treat fungal infections.

Susceptibility patterns of Escherichia coli and streptococcal isolates from bovine mastitis cases to antibiotics and selected South African plant extracts with known antibacterial activities

Bovine mastitis, an inflammatory condition affecting the mammary glands of dairy cattle, poses a significant economic burden on the dairy industry. Staphylococcus species, Streptococcus species and Escherichia coli are common pathogens. Managing mastitis typically involves antibiotics, but antimicrobial resistance (AMR) is a growing concern, promoting further research exploring alternative treatments including plant extracts. This study aimed to determine the antibiotic resistance of E. coli and streptococcal isolates from mastitis cases, and to investigate four indigenous South African plants for their selective antibacterial activities against these pathogens. The antimicrobial susceptibility of the bacterial strains was determined using a standard disc diffusion method. Minimum inhibitory concentration (MIC) values of acetone and ethanol extracts of Searsia lancea, Indigofera frutescens, Erythrina caffra and Antidesma venosum were determined against the bacterial isolates using a serial microdilution assay, and cytotoxicity was also investigated. The results showed that 82.14% of the clinical isolates tested were resistant to at least one antimicrobial agent used, and 52.17% of the antibiotic resistant isolates were multidrug resistant. All plant extracts had antibacterial activity against all the bacterial isolates, but S. lancea demonstrated higher efficacy compared to other plants. The MIC values ranged from 0.01 to 2.50 mg/mL, with the lowest range obtained with the acetone extract of S. lancea (0.01 to 0.57 mg/mL). Furthermore, the extracts were relatively non-cytotoxic to bovine dermis and Vero cells, with the highest mean selectivity index value of 25.70 recorded with S. lancea. This study highlights the growing concern of AMR in livestock management, and demonstrates the promising therapeutic potential of the selected plant species, particularly S. lancea, in treating bovine mastitis. Further exploration of S. lancea is recommended to develop novel alternative or complementary formulations for mastitis management.

Chemical profiling and inhibitory effects of selected South African plants against phytopathogenic bacteria and fungi of tomato

Soilborne pathogens are economically important, causing great losses in agricultural production globally. The high cost and toxicity of antibiotics, coupled with the development of drug-resistant bacteria, has awakened interest in finding alternative methods of plant-pathogen control. This study aimed to screen extracts of selected plants against phytopathogenic bacteria and fungi that infect tomatoes, and to profile their chemical constituents. The antimicrobial activity of acetone, water and dichloromethane: methanol (DCM/MeOH = 1:1) extracts from leaves of ten plants was examined against five phytopathogenic bacterial strains and one fungal strain using a serial microplate dilution method to determine the minimal inhibitory concentration (MIC) values. Gas chromatography-mass spectrometry (GC–MS) was used for profiling constituents in the acetone and DCM/MeOH extracts. The MIC values indicated weak antibacterial activity of all the water extracts against tested bacterial strains. Acetone and DCM/MeOH extracts of Leucosidea sericea and Searsia lancea had very good to outstanding antibacterial activity against most of the tested bacteria with MIC values ranging between 19.5 and 78 µg/mL. All extracts were not active against Fusarium spp. except for the acetone extract of Cotyledon orbiculata and the water extract of Leonotis leonurus which inhibited the growth of F. oxysporum with MIC = 39 and 97.5 µg/mL after 24 h, with further incubation resulting in MICs of 156 and 469 µg/mL respectively. The GC–MS analysis of the acetone and DCM/MeOH extracts indicated the major peaks of 9-octadecenamide, (Z)-, octadecanoic acid and dodecanamide which were present in almost all the extracts. The 9-octadecenamide was found to be the most highly concentrated compound in most extracts. Leucosidea sericea and S. lancea, therefore, contain bioactive compounds that may be used as broad-spectrum antimicrobials against phytopathogenic bacteria and fungi.

Diet Mixing and Supplementation Present an Opportunity to Increase the Use of Encroaching Woody Plants by Goats.

Along with the woody plant expansion that is predicted to continue at the expense of the grassy layer is the increasing societal demand for animal protein and livestock products. Unless concerted efforts by land users, ecologists, and animal scientists are made to increase the utilization of trees and shrubs as forage, it will be impossible to meet future demand for meat and meat products. We conducted two short-term pen experiments to determine the effects of (1) supplementation with polyethylene glycol (PEG-a polymer purported to bind and neutralize the negative effects of tannins), a high-protein source (soybean meal), and a high-energy source (yellow maize grain) and (2) diet mixing (single-species vs. multispecies diets) on the intake of condensed tannin-rich woody plants (i.e., Searsia lancea, S. pyroides, and Euclea crispa) by goats. While all three forage species were used in the diet mixing experiment (Exp. 2), only E. crispa was used in the supplementation experiment (Exp. 1). Supplementing goats with energy- and protein-rich sources significantly increased the intake of E. crispa (p < 0.05), 713.4 g ± 13.5 and 760 g ± 28.9, respectively, whereas those on the control diet maintained their intake at 540.32 g ± 11.2. Although PEG tended to increase the consumption of E. crispa by goats, the observed increase was not significant (p > 0.05) from that observed in other treatments. In the diet mixing experiment, goats offered a combination of all three forage species attained substantially higher dry matter intakes compared to the goats offered these species individually (p < 0.05). While longer-term field experiments are needed in the African savannas, we postulate from the current results that management strategies that provide animals with (1) a variety of species in the diet vs. monocultures and (2) a combination of nutrient-rich and tannin-rich species may improve the ability of goats to consume chemically defended woody plants.

In vitro Evaluation of Sersia Lancea Root Extract for the treatment of Common Microbial Infections

Searsia lancea (SL) has been exploited by native healers in the Southern African region for the treatment of various bacterial and fungal infections. This study was aimed to analyze the antimicrobial activity and the minimum inhibitory concentration of SL root extract against Candida albicans, Candida glabrata, E.coli and Staph aureus. The maceration technique was used as the extraction method. The antifungal and antibacterial activity was determined by the agar well diffusion method. The agar dilution method was used for estimating the minimum inhibitory concentration (MIC). The biological investigations in this study clearly demonstrate the antibacterial and antifungal potential of SL aqueous and organic extract. The aqueous and organic Sersia Lancea root extract achieved zone of inhibition from 17.1-40.2mm against the tested organisms. The order of susceptibility of the pathogens to the tested extracts was found to be S.aureus&gt;Candida Albicans&gt;E.coli&gt;Candida Glabrata. The results of the MIC experiment demonstrate that Candida Albicans and E.Coli were susceptible to the MIC of 3.12mg/mL for the SL distilled water root extract . The MIC of the aqueous extract against Candida glabrata and Staph Aureus were 6.25 and 12.5mg/mL respectively. All the microrgaisms were susceptible to MIC 6.25mg/mL for the DCM extract except for Candida Glabrata with MIC of 12.5mg/mL. The current work has not performed any isolation or structural elucidation studies for the potential compounds responsible for the antimicrobial activity. This is the first report to demonstrate the antibacterial and antifungal property of SL root extract. The results in this work provide scope for future studies to elucidate the structure of potential actives in SL root extract and to test their potential as possible antibacterial and antifungals.

In Vitro Antibacterial Activity of Selected South African Plants against Drug-Resistant Staphylococci Isolated from Clinical Cases of Bovine Mastitis

Bovine mastitis in dairy livestock production is a serious economic problem causing milk production losses and increased management costs. Staphylococcus aureus and non-aureus staphylococcus (NAS) are important causes of bovine mastitis. Antimicrobial resistance can limit the control of mastitis pathogens. Antibacterial and cytotoxic activities of acetone and ethanol extracts of nine South African plants were determined against reference and drug-resistant staphylococci isolated from clinical cases of bovine mastitis. The nine plants, namely, Antidesma venosum, Elaeodendron croceum, Erythrina caffra, Indigofera frutescens, Pleurostylia capensis, Searsia lancea, Searsia leptodictya, Trichilia emetica, and Ziziphus mucronata, were chosen for research material. The antibacterial activity of extracts was determined using a serial microdilution method, while a tetrazolium-based assay was used to determine their cytotoxicity against Vero cells. The values of antibacterial minimum inhibitory concentration (MIC) obtained were promising, with MIC ranging between 0.01 and 1.41 mg/mL. Generally, acetone extracts of most plants had better activity than their ethanol counterparts. The S. aureus strains were more susceptible to all the extracts than the NAS strains. The plant extracts’ half-maximal toxicity (LC50) was higher than 0.02 mg/mL, which is the recommended cytotoxic cut-off concentration. The ethanol extract of E. caffra, which showed better MIC values than its acetone extract, had the highest mean selectivity index (SI) of 8.30. Among the plants tested, S. lancea exhibited the most potent antibacterial activity, suggesting its potential usefulness as a broad-spectrum antibacterial agent against staphylococci associated with bovine mastitis, at relatively non-cytotoxic concentrations. Therefore, it is recommended for further investigation.

Seasonal effects of Rhus lancea and Celtis africana on intake, preference, and physiological responses in South African indigenous goats

This study investigated the seasonal effects of Rhus lancea and Celtis africana leaves on preference, intake, weight, and serum metabolites in South African indigenous, mature, male goats. Twelve mature, male goats weighing 34 ± 5.9 kg (mean ± SD) were randomly allocated to two groups of six and kept in metabolic crates for periods of 21 days in October 2015 and March, May, and August of 2016. A browser diet of R. lancea and C. africana and a control diet (lucerne and concentrates) were randomly allocated to each group. Measurements taken included nutritional composition of browse per season, and browse preference, intake, weight changes, and serum metabolites in the goats. The acid detergent fibre (24– 36%) and neutral detergent fibre (26.9–70.4 %) in R. lancea over the months were greater than in C. africana (50.3–53.2% and 49.4–55.4%, respectively). In the preference study, the goats preferred C. africana more in October (51.2 vs 48.8%), March (51.4 vs 48.6%), and May (54.3 vs 45.7%). Goats on the browser diet lost weight in March, May, and in August whereas those on the control diet gained weight. The serum urea concentration of goats consuming browser diets in May and August (1.8–3.3 mmol/l) was lower than the normal range, consistent with animals failing to derive their protein requirements from the diet. Goats prefer to browse C. africana more than R. lancea. The study also indicated the need for supplementation to meet maintenance requirements in animals fed R. lancea and C. africana.

Recycling of Trees Planted for Phytostabilization to Solid Fuel: Parametric Optimization Using the Response Surface Methodology and Genetic Algorithm.

Biomass resources are gaining attention to address environmental issues, ensure energy efficiency, and ensure long-term fuel sustainability. The use of biomass in its raw form is known to present a number of issues, including high shipping, storage, and handling costs. Hydrothermal carbonization (HTC), for example, can increase the physiochemical properties of biomass by converting it into a more carbonaceous solid hydrochar with enhanced physicochemical properties. This study investigated the optimum process conditions for the HTC of woody biomass (Searsia lancea). HTC was carried out at varying reaction temperatures (200-280 °C) and hold times (30-90 min). The response surface methodology (RSM) and genetic algorithm (GA) were used to optimize the process conditions. RSM proposed an optimum mass yield (MY) and calorific value (CV) of 56.5% and 25.8 MJ/kg at a 220 °C reaction temperature and 90 min of hold time. The GA proposed an MY and a CV of 47% and 26.7 MJ/kg, respectively, at 238 °C and 80 min. This study revealed a decrease in the hydrogen/carbon (28.6 and 35.1%) and oxygen/carbon (20 and 21.7%) ratios, indicating the coalification of the RSM- and GA-optimized hydrochars, respectively. By blending the optimized hydrochars with coal discard, the CV of the coal was increased by about 15.42 and 23.12% for RSM- and GA-optimized hydrochar blends, respectively, making them viable as an energy alternative.

Seed dispersal phenology of encroaching woody species in the Free State National Botanical Garden, South Africa

AbstractWe investigated seed dispersal phenology of bird‐dispersed and encroaching woody species in the Free State National Botanical Garden (FSNBG), South Africa, over a 12‐month period. Results from defecated seeds' collection in 17 roosting sites show that a total of 22,161 seeds belonging to 14 woody species under 11 families were eaten and dispersed by foraging birds with seeds of six species being frequently dispersed. The native species had a larger number of dispersed bird‐ingested seeds than the alien and invasive species. Seeds' collection suggested that out of five fruiting species, birds mostly preferred the red (Ziziphus mucronata, Ehretia rigida and Viscum rotundifolium) and black fruits (Olea europaea subsp. africana and Diospyros lyciodes). Ziziphus mucronata and O. subsp. africana seeds were dispersed in significantly higher numbers between March and July (mean ± SE: 47.1 ± 11.6; 51.4 ± 9.0), while Searsia lancea and E. rigida were mostly dispersed between August and December (221.6 ± 74.1; 373.6 ± 91.5)—a dichotomy that could minimise competition for dispersal agents while sustaining the resident bird species. Over 480 h of camera trapping, 22 bird species were captured, of which seven displayed high foraging frequency, and were resident in behaviour, while six species were migratory and colonial avian frugivores, including two alien bird species. We conclude that the reported bush encroachment is a likely result of high propagule pressure by resident frugivorous birds and colonial wintering birds in FSNBG, together with low fruit diversity in the grassland habitat.

Effects of browse legume species addition on nutritional composition, fermentation characteristics and aerobic stability of Opuntia cladodes silage

Forage legumes are commonly used as an absorbent additive in high-moisture silages. Thus this study was carried out to assess the nutritive value, fermentation characteristics and aerobic stability of Opuntia–legume browse mixed silages. Five browse legume species (Leucaena leucocephala, Acacia mellifera, Searsia lancea, Prosopis velutina, and Grewia flava) were mixed with Opuntia cladodes. The silage mixture was formulated at a ratio of 60 Opuntia cladodes: 40 leguminous browse species and ensiled in polythene bags and kept in a laboratory for 42 days to determine chemical composition and fermentation characteristics. Silage samples were also subjected to an aerobic stability test. One-way analysis of variance in a completely randomised design was used to analyse the data. The pH values for silages made from Opuntia cladodes with L. leucocephala, A. mellifera and G. flava were lower than 4.8, which is considered an indicator of good-quality silage. The water-soluble carbohydrates content of silages made with Opuntia cladodes and S. lancea and G. flava was within the range of 8–12 g/kg dry matter, which is sufficient for good fermentation. The highest CO2 production, which signifies poor aerobic stability, was recorded for the control silage (Opuntia) compared to all Opuntia–legume mixed silage treatments. The addition of legume browse leaf-meal to Opuntia cladodes improved nutritive value, fermentation characteristics, and silage quality. Therefore, despite some limitations, Opuntia–legume browse silages, particularly Opuntia–G. flava and Opuntia–L. leucocephala, proved to be beneficial for livestock, as they meet the nutritional requirement of a ruminant. Significance:This study underlines the importance of co-ensiling Opuntia cladodes and high protein legume browse hay to offer an alternative feeding strategy for ruminant livestock and ensure sustainable provision of high-quality feed during dry periods.

Khoekhoe Lexical Borrowing in Regionalised Afrikaans

This brief paper aims to draw attention to the widespread and ongoing phenomenon of lexical borrowing from Khoekhoe-branch languages into regional Afrikaans. A case study of one Afrikaans plant name loaned from Khoekhoe-branch languages, karee (Searsia lancea, Searsia spp.), is used to demonstrate how post-shift phonological attrition can lead to lexical conflation, and hence to semantic extension. This paper strongly recommends that public-facing scientific organisations take greater care when providing linguistic information to lay communities, and also motivates increased study of the behaviour of click consonants in a post-shift context in order to develop a clearer understanding of Khoekhoe-branch language history.Keywords: Language history, loanwords, phonological attrition, semantic reanalysis, Khoekhoe, Afrikaans

Effects of Searsia lancea hydrochar inclusion on the mechanical properties of hydrochar/discard coal pellets

The utilization of biomass as a solid fuel for co-firing has received great attention from boiler manufacturers as a clean coal technology (CCT) option. This research aimed to produce biocoal pellets, as a clean energy fuel, using hydrochar from trees planted to rehabilitate acid mine drainage (AMD) water and fine coal discards. The hydrochar was synthesized by hydrothermal carbonization of Searsia lancea harvested from AMD-contaminated land at a temperature of 280°C and a residence time of 90 minutes. It was blended with discard coal (-1 mm) at ratios of 25% and 50% hydrochar to produce different forms of solid pelletized biocoal (BC). The physicochemical and mechanical properties of each of the biocoal pellet blends were determined. The 100% hydrochar had the highest calorific value of 29.99 MJ/kg, while the raw discard coal had a calorific value of 16.73 MJ/kg. The ash content decreased from 42% in the discard coal to 25% in the blend of 50% coal and 50% hydrochar biocoal pellets. Biocoal pellets comprising 25% hydrochar and 75% discard coal (BC25HC/75COAL) displayed the best mechanical properties (compressive strength 3.06 MPa) of all the fuels, but the physicochemical properties were inferior to the BC50HC/50 COAL pellets. This research has demonstrated that hydrochar synthesized from a tree species planted for hydraulic control of AMD has the capability to act as a binder for improving the mechanical properties and energy characteristics of fine discard coal.

Interspecific competition in germination of bird-dispersed seeds in a habitat with sparse tree vegetation in South Africa

BackgroundBy transporting and scarifying the seeds during ingestion, avian frugivores reduce the competition with siblings, and may improve the germination which is critical for dispersal effectiveness and population recruitment. However, generally, there is limited knowledge on how deposited seeds interact/compete in the new microsite. We tested the hypothesis that the bird-dispersed seeds benefit from improved germination after their passage through the bird’s gut; and we investigated the potential impact of seed density on competition at the microsites by determining whether seed density and species diversity influence germination in the Free State Province, South Africa.ResultsOverall, the results partly supported the hypothesis. Germination trials with defecated seeds of five plant species compared with the manually depulped seeds showed that only Searsia lancea had significantly higher seed germination success and improved germination speed after passage through the bird gut while Ziziphus mucronata only benefited rapid germination. There was a significant correlation between seed size and the germination of bird-ingested seeds except in Olea subsp. africana possibly due to possession of extremely hard protective seed cover. Seed competition experiments pointed to Z. mucronata and O. subsp. africana having significant germination performance that was positively correlated to seed density and seed size while Ehretia rigida did not germinate at all. Seed species diversity in the germination trays did not have a significant impact since the seeds of two former plant species consistently displayed significantly higher germination across the competition levels.ConclusionsWe conclude that different plant species respond differently to seed ingestion by birds, and that further long-term tests for germination physiological responses of the seeds’ samples used in this study are required since poor germination observed in other tree/shrub species cannot be attributed to competition solely.

Potential nematicidal properties of plant extracts against Meloidogyne incognita

Among the most destructive pests affecting plant growth and yield worldwide are root-knot nematodes (Meloidogyne spp.). Currently, the shift from the use of chemical nematicides is trangressing globally towards choices such as organic nematicides extracted from plant substances. Plant secondary metabolites have been identified as compounds responsible for nematicidal activities in different plant species and are favored nematicidal agents because of their safe environmental record and affordability. Phytochemical screening, DPPH● scavenging capacity and nematicidal properties of eight different plant extracts under in vitro and greenhouse conditions were investigated against the egg mass hatching of the nematode, M. incognita. Four concentrations (0.2, 0.4, 0.6 and 0.8 mg/mL) with distilled water serving as a control were replicated three times and arranged in a completely randomized design (CRD) in an incubator at 25 ± 3 °C. The phytochemical analysis showed that the highest total flavonoids, condensed tannins and phenolic contents were found in Vernonia colorata (88.71 mg/g QE), Searsia lancea (406.16 mg/g CCE) and Pelargonium sidoides (175.95 mg/g GAE), respectively, with DPPH● scavenging IC50 values of 84.94, 14.40 and 6.64 µg/mL respectively. Our results further revealed that all treatments with increasing concentrations suppressed egg mass hatching after 72 h. Cucurbita maxima methanolic crude extract with DPPH● scavenging IC50 value of 168.20 µg/mL significantly reduced egg mass hatchability by 77–96% after 72 h. Under greenhouse conditions, results showed a significant (P < 0.01) inhibition of 97% on second-stage-juveniles penetration/establishment on tomato roots, with 100% root gall development inhibition on seedlings treated with V. colorata methanolic crude extract. In conclusion, all eight plant extracts showed promising nematicidal activity at 0.8 mg/mL.

Effects of Fire Frequency on Woody Plant Composition and Functional Traits in a Wet Savanna Ecosystem

The objective of this study was to assess the effect of fire frequency on vegetation taxonomic and functional diversity in a wet savanna ecosystem, eastern Zimbabwe. The study area was stratified into three fire frequency regimes using a 15-year fire history (2000–2014) across the landscape: high (HFF: burnt every 1-2 years), medium (MFF: burnt every 3-4 years), and low (LFF: burnt every 5-6 years). Data were collected from a total of 30 plots measuring 20 m × 20 m each between March and May 2018. In each plot, we recorded tree maximum height (Hmax), woody plant density, basal diameter, resprouting capacity, and bark thickness. We calculated species evenness, diversity, functional richness (FRic), Rao’s Quadratic Entropy (RaoQ), functional redundancy, and relative bark thickness. We recorded 1,031 individual trees belonging to 24 species across the three fire regimes. Significant differences across the three fire regimes were recorded for Hmax, woody plant density, and relative bark thickness P &lt; 0.05 . Hmax and woody plant density were higher in LFF than HFF regimes while relative bark thickness was higher in HFF than in the LFF regimes. Species evenness was significantly higher in HFF and MFF regimes than LFF regime P &lt; 0.05 , while FRic and functional redundancy significantly increased with decreasing fire frequency P &lt; 0.05 . However, no significant differences were recorded for resprouting capacity, species richness, taxonomic diversity, and RaoQ P &gt; 0.05 . Species like Cassia petersiana, Cussonia spicata, Vachellia spp., and Rhus lancea were associated with LFF, while species like Protea gaguedi, Brachystegia utilis, and Vangueria infausta showed a strong association with HFF to MFF. Our study demonstrated that a combination of taxonomic and functional diversity metrics is adequate to evaluate the response of savanna vegetation to fire. We recommend a further assessment on vegetation composition using other elements of fire regimes.

Effects of soil type on density of trees and nutritive value of tree leaves in selected communal areas of South Africa

This study aimed to describe the distribution and nutritive value of woody species growing in clay-loamy and red-brown sand from selected localities of North West, South Africa. Three 2.2 km transects, radiating from homesteads, which served as replicates, were established at each of four selected grazing areas. Nine 10 × 10 m homogenous vegetation units (HVU), 20 m apart, were marked in each transect. Woody plant density, height and canopy cover (CC), were recorded, and chemical properties and degradability via in vitro ruminal fermentation of harvested leaves were measured. Raisin bush (Grewia flava), Buffalo thorn (Ziziphus mucronata) and Camel thorn (Vachellia erioloba) were the common species across both soil types. Soil type influenced (P &lt;0.05) plant density, CC, total tree equivalent (TTE) and plant height. Areas with red-brown sandy soil had higher (P &lt;0.05) total plant density (827.7 plant/ha), CC (9.6%) and TTE (2886.4 TTE/ha) than those with clay-loamy soil. Vachellia erioloba leaves in clay-loamy soil had the highest (P &lt;0.05) crude protein content (151.2 g/kg DM). Leaves of Searsia lancea species that were harvested from both the clay-loamy and red-brown sandy soils had the highest (P &lt;0.05) amounts of condensed tannins (0.915 AU550/200 mg and 0.917 AU550/200 mg, respectively). Searsia lancea leaves had the lowest (P &lt;0.05) in vitro ruminal nitrogen degradability values in both soil types. The leaves of Z. mucronata and G. flava leaves have potential as protein supplements for ruminants owing to their higher crude protein content and in vitro ruminal N degradability.&#x0D; Keywords: canopy cover, feeding value, plant height, semi-arid, species diversity, tree equivalent

Co-combustion of Searsia lancea and Tamarix usneoides with high ash coal

This study utilized two indigenous South African trees, Searsia lancea and Tamarix usneoides, which had been planted for phytostabilisation of heavy metal and Acid Mine Drainage (AMD) contaminated in soils on AngloGold Ashanti mining properties. After twelve years of growth, the two species were harvested from four different trial sites, and divided into different plant components including root, wood, twigs and leaves. These components were analysed for their physicochemical properties, both individually and in combination, with specific emphasis on their properties for direct combustion and co-combustion with coal. Significant differences in fuel characteristic were found between both tree species and their divided plant COMPONENTS and the coal used in the cofiring tests. Searsia lancea leaves possessed a calorific value of 19.21 MJ/kg compared to 16.73 MJ/kg from the coal utilized. All the Searsia lancea blends, irrespective of trial site location, possessed lower ash contents (3.77–6.60%) relative to Tamarix usneoides plant blends which were found to have ash contents of 7.48–8.98%.The Derivative curve (DTG) obtained from the combustion tests conducted on the two tree species indicated that both exhibited relatively low ignition temperatures and high reactivities. Raw 100% Tamarix provided the highest combustion efficiency of all the samples tested. The emission test conducted on the combustion of the Searsia lancea samples, from the Madala site, along with its coal blends, shows a clear trend in the reduction of the SOX and NOX emission between the raw 100% Tamarix, its blends and the coal utilized. This preliminary test shows that both indigenous tree species are capable of being used as a suitable and compatible valuable source of biomass for combustion and co-combustion with South African high ash coal although minor qualitative and performance characteristics occur between them.

Bioassay-guided purification, GC-MS characterization and quantification of phyto-components in an antibacterial extract of Searsia lancea leaves

Phytocompounds in an aqueous methanol (70% MeOH) leaf extract of Searsia lancea were separated using liquid-liquid partitioning techniques and gravity-assisted column chromatography. The resultant fractions were screened for antibacterial properties (minimum inhibitory concentration, MIC) against four bacterial strains (Enterococcus faecalis, Klebsiella pneumoniae, Neisseria gonorrhoeae and Staphylococcus aureus). Bioactive fractions were purified using preparative thin layer chromatography (TLC) and subjected to further antibacterial screening. Phytocompounds in antibacterial sub-fractions were characterized and quantified using Gas Chromatography-Mass Spectrometry (GC-MS). An ethyl acetate sub-fraction purified from the aqueous methanol extracts of the leaves demonstrated potent antibacterial properties (MIC range: 31-61 µg/ml against E. faecalis and S. aureus). Based on GC-MS analysis, 81.5% of the sub-fraction consisted of broad-spectrum antibacterial compounds namely tetracosanol (43.98%) and nonadecanol (37.5%). Current research findings support the traditional use of S. lancea leaves to manage gastro-intestinal disorders and gonorrhoea.

Stem volume and tree biomass harvested by different thinning intensities from dense and sparse karee stands in Central Bushveld, South Africa

The aim of this study was to determine the aboveground stem volume and tree biomass of the multi-stemmed karee tree (Searsia lancea) for its potential use for producing wood chips and/or pellets. A stratified random sampling was done, by selecting two blocks with both sparse and dense Karee stands. In each block, three sparse and three dense karee stands were identified. Within each block, three thinning treatments of only karee stems (no cutting, 50% cutting and 100% cutting by number of stems) were randomly allocated to the selected stands. The average moisture content of karee wood was 35.43%. A 50% cutting in sparse stands produced a total dry biomass of 8.51 ± 3.63 t ha−1 and stem volume of 11.92 ± 6.28 m3 ha−1, and in dense stands it produced a total dry biomass of 16.05 ± 2.42 t ha−1 and stem volume of 22.97 ± 4.38 m3 ha−1. The 100% cutting (clear-felling) in sparse stands produced a total dry biomass of 10.02 ± 4.48 t ha−1 and stem volume of 14.10 ± 4.01 m3 ha−1, and in dense stands it produced 33.80 ± 2.25 t ha−1 and 60.64 ± 22.97 m3 ha−1. Thus, the clear-felling biomass was significantly higher than that of 50% cutting, which was supported by ANOVA results for tree biomass (p = 0.0078). In contrast, in terms of stem volume, the p-value was 0.08, indicating that 100% cutting was not significantly higher than the 50% cutting treatment. Dense stands were significantly higher than sparse stands in both tree biomass and stem volume comparisons. Generally, this study showed that there is a great potential to utilise stems of karee for biomass.