Euclea Racemosa Research Articles

Antidiabetic Potential and Chemical Profiling of Chloroform Fraction from Euclea racemosa subsp. schimperi In Vitro

Background: The chloroform fraction (CHCl3 Fr.) of Euclea racemosa subsp. schimperi has enormous interest for its potential therapeutic properties in managing diabetes and oxidative stress-related conditions. This study aimed to evaluate the chemical composition and biological activities of CHCl3 Fr. through LC-ESI-MS/MS and GC-MS analyses. Methods: The CHCl3 Fr. was analyzed using LC-ESI-MS/MS for identification of bioactive compounds, and its inhibitory effects on α-amylase and α-glucosidase were assessed in vitro. Additionally, the impact on insulin secretion, C-peptide levels, and oxidative stress markers (MDA and NO) were measured. Results: Nineteen bioactive compounds, including flavonoids, pentacyclic triterpenes, and monounsaturated fatty acids, were identified in the chloroform fraction (CHCl3 Fr.). It significantly inhibited α-amylase and α-glucosidase, with IC50 values of 21.16 ± 2.13 and 13.49 ± 0.83 µg/ml, respectively. In insulin-resistant Huh7 cells, CHCl3 Fr. reduced glucose levels and increased insulin and C-peptide levels (p < 0.05). While it decreased malondialdehyde and nitric oxide, it did not significantly enhance catalase or total antioxidant capacity (p > 0.05). Compared to metformin, CHCl3 Fr. showed less efficacy but may improve insulin resistance and reduce oxidative stress, likely due to its bioactive compounds. Conclusion: The presence of diverse bioactive compounds contributes to the antidiabetic effects of CHCl3 Fr. from E. r. ssp. shimperi, showed its potential as a natural therapeutic agent for diabetes management and oxidative stress reduction. Further investigations are warranted to explore its clinical applications and underlying mechanisms.

Nutritional Composition and Antinutritional Factors of Five Wild Edible Fruits Grown in the Mekdela District, South of Wollo, Ethiopia.

This study was carried out to determine the mineral content and nutritional properties of five wild fruits Rhus vulgaris, Rosa abyssinica, Rhus natalensis, Euclea racemosa, and Ficus sur. The proximate composition parameters (moisture, ash, crude fiber, crude fat, and crude protein) and antinutritional factors were evaluated using methods of the Association of Official Analytical Chemists and elemental analysis using the atomic absorption spectroscopy technique. Among the five wild edible fruit species, Rhus vulgaris had the highest carbohydrate content (83.3 ± 0.28 g/100 g) and a high total energy (344.5 ± 2.21 kcal/100 g). Euclea racemosa was found to have the maximum ash content (12.8 ± 0.37 g/100 g), protein content (3.22 ± 0.01 g/100 g), and moisture (16.24 ± 0.003 g/100 g), respectively. Rhus natalensis showed the highest fiber content (9.54 ± 0.003 g/100 g). Mineral analysis showed that local wild fruits contained a considerable amount of minerals. The calcium concentration ranged from 99.51 mg/100 g in Euclea racemosa to 160.12 mg/100 g in Ficus sur. Potassium concentration varied from 54.34 mg/100 g in Euclea racemosa to 234 mg/100 g in Rhus vulgaris. Iron ranges from 21.4 mg/100 g in Rosa abyssinica to 41 mg/100 g in Rhus natalensis, and zinc ranges from 2.3 mg/100 g in Rhus vulgaris to 4.2 mg/100 g in Ficus sur. A high saponin content (2.12 mg/100 g) and a low tannin content (0.23 mg/100 g) were obtained in Rosa abyssinica. The phytate content (1.52 mg/100 g) and the oxalate content (0.9 mg/100 g) were high in Rhus natalensis. In conclusion, the present study shows that wild fruits can be used as food supplementation in food in a safe area.

Growth and Yield Performance of Oyster Mushroom (P. ostreatus (Jacq.: Fr.) Kummer) Using Waste Leaves and Sawdust

Mushroom is a fungus growing on decomposing substrates. It is the substrate type that affects the yield and quality of oyster mushroom. It can be cultivated by landless people to alleviate poverty. The objective of this study was to evaluate the growth and yield performance of oyster mushroom in waste leaves and sawdust. Spawn were purchased from YB Plant Micropropagation Plc; Mekelle, Tigray, Ethiopia. Euclea racemosa waste leaves, Cordia africana waste leaves, and sawdust were prepared and inoculated with the spawn. Cotton husks were used as a control. 60 grams of spawn was used for 1000 g of each substrate and supplemented with 3% wheat bran and 1% gypsum. The data were analyzed using SPSS version 20. A one-way ANOVA model was used to indicate significant mean differences at 95% confidence interval between flushes. Treatment means were compared using Turkey’s t test. In the first flush, primordial initiation was fastest and took 6.33 days in Cordia africana waste leaves and provide higher (166 ± 48.49, 131.6 ± 32.71, 49.66 ± 15.53 gram) mean yield and BE (16.6 ± 4.84, 13.16 ± 3.27, 4.96 ± 5.5%) in the 1st, 2nd, and 3rd flushes, respectively. However, in the 2nd and 3rd flushes, a lower (24.66 ± 4.61, 14.66 ± 0.57 gram) mean yield was recorded in Euclea racemosa waste leaves. Higher (10.63 ± 1.00, 7.83 ± 3.92, 6.56 ± 2.26 cm) mean pileus diameter and pileus thickness (8.3 ± 1.47, 7.76 ± 1.32, 4.10 ± 0.85 mm) were noted in sawdust in the 1st, 2nd, and 3rd flushes, respectively. This study confirmed that the waste leaves of Cordia africana and Euclea racemosa could be used as an alternative substrate for the cultivation of oyster mushroom.

Evaluations of the in vivo laxative effects of aqueous root extracts of Euclea racemosa L. in mice

BackgroundManagement of constipation with currently available modern medicines is costly and chances of side effects are high. This limits their clinical usefulness and remain to be solved, and calls for investigations of new and better compounds. The experimental plant, Euclea racemosa L. (E. racemosa L) is among plants, which are used for management of constipation traditionally but its effect is not yet experimentally validated. Therefore, the aim of the present study is to investigate the laxative effects of this plant. MethodsThe laxative effects of aqueous root extracts of E. racemosa L. were evaluated using gastrointestinal motility, laxative activity, and gastrointestinal secretion tests. ResultsIn the laxative test, the 200 and 400 mg/kg doses of plant extract showed a significant increase in percent fecal water content. The plant extract also significantly accelerated the charcoal meal in gastrointestinal motility test of loperamide-constipated mice. Moreover, the experimental plant produced significant Gastrointestinal (GI) transit ratio at all doses but failed to produce a significantly higher fluid accumulation except 400 mg/kg doses of extract in gastrointestinal secretion test. The observed effect of the aqueous root extract might be due to the presence of secondary metabolites. The aqueous root extract of E. racemosa L. revealed the presence of terpenes, saponins, flavonoids and phenols when it was subjected to phytochemical screening. ConclusionThe investigation obtained from this study suggested that E. racemosa L. has a beneficial effect in producing laxative effect and this substantiate the traditional use of the plant for its claimed indication.

Antimicrobial dyeing of cotton from Euclea racemosa root

PurposeThe purpose of this research is to develop an environmentally friendly antimicrobial dyeing of cotton fabric from the root of Euclea racemosa. Textile phytochemical finishing is in high demand worldwide because of its low toxicity, low pollution, ease of availability, renewability, pharmacological effects and non-carcinogenic properties, as well as its multifunctionality, rapid process stages and potential health benefit.Design/methodology/approachThe cotton fabric was dyed with aqueous extracts of Euclea racemosa root dyes. Dyes were extracted for 20 min at pH 7.43 at room and boiling temperatures with material-to-liquor ratios (MLRs) of 1:5, 1:10, 1:15 and 1:20, altering one variable at a time, and the cotton fabric was colored using a post-mordanting procedure at 50°C with an MLR of 1:20. Using a properly cleaned Petri plate, the colored samples were tested in vitro for antibacterial activity. A spectrophotometer was used to assess color strength and shade depth, as well as wash fastness and annual rubbing fastness tests for both wet and dry.FindingsL* = 36.29, a* = 58.56, b* = 32.46 and K/S = 0.51 were the CIELAB values for dye extracted at boiling temperature. L* = 47.14, a* = 42.23, b* = 49.61 and K/S = 0.38 were the CIELAB values for dye extracted at room temperature. The wash and rubbing fastness of the dyed samples were outstanding and the dyed cotton fabrics were found antibacterial against Gram-negative bacteria Escherichia coli.Originality/valueDyes derived from the E. racemosa root could be used to develop a new antibacterial cotton fabric dye.

Woody Plant Species Diversity of Lay Agerit Giorgis Natural Forest, Merabeti District of North Shoa Zone in Amhara Region, Ethiopia

Ethiopia is one of the biodiversity reach areas in the world. This study was conducted in Lay Agerit Giorgis forest is located in Merabeti district of North Shoa zone in Amhara region. This inventory was done with the aimed of woody plant species diversity documentation; determine floristic composition and regeneration status of woody plant species in Lay Agerit Giorgis Natural Forest. Systematic sampling was employed for the purpose of woody plant inventory in this area. The total of 34 quadrates were established with 6 transects in each of them 100meter apart and also 100meter distance in between plots with the sample plot area enumerated as the 10X 50meter. The major forest disturbance factors were recorded 35.16% light and moderate Browsing, 36.26% light and moderate Grazing and 28.57% light and moderate disturbance levels shows by logging /cutting. A total of 48 woody plant species belong to 38 genera and 27 families were recorded. The most frequent genera in the woodland were (Fabaceae), (Capparidaceae), (Celastraceae) and (Tiliaceae), respectively. The species frequency ranges between 2.94 – 76.4% with Dichrostachys cinerea (74.4%), Acacia tortilis (67.6%), each Dodonaea angustifolia and Euclea racemosa (64.7%) are among the top and Gardenia ternifolia, Ficus sur, Commiphora africana, Celtis africana are among the lowest in frequency distribution (2.94%). Setting high priority is needed to conserve these endangered woody plant species following either the ex-situ or field Gene bank or both conservation systems.

Environmental and anthropogenic factors affecting natural regeneration of degraded dry Afromontane forest

Natural regeneration of trees may provide a cost‐effective way to restore degraded tropical dry forests, but the factors predominantly affecting natural regeneration success are poorly understood. We performed a multifactor analysis of natural regeneration in an Afromontane forest in Northern Ethiopia. Inventory plots of 400 m2, each with a nested 9 m2 subplot, were systematically established. All trees larger than 5 cm DBH and natural regeneration were identified and recorded in the plots and subplots, respectively. Variables describing climate, topography, soil, vegetation, and indications of local human degradation were collected. Determinants of regeneration presence and abundance were analyzed using Hurdle negative binomial regressions. Sixty‐nine woody species were represented in the regeneration, with an average regeneration density (SE) of 14,700 (51) ha−1. The presence of regeneration was positively associated with canopy cover (p < 0.001), distance to the road network (p = 0.04), precipitation (p = 0.003) and tree species diversity (p = 0.03), and negatively with Northing (p = 0.003). The regeneration abundance was positively associated with soil quality (p = 0.001), canopy cover (p = 0.04), and precipitation (p = 0.01). Including the abundance of dominant species in the tree canopy and regeneration layers in the regression model did not affect the presence of natural regeneration, but it clearly affected regeneration abundance. In such a model, the regeneration abundance was positively associated with Euclea racemosa seedlings abundance and negatively associated with the basal area of Dodonaea angustifolia (p = 0.02) and Rhus natalensis (p = 0.04). In this model, forest degradation (p = 0.01) negatively affected the late‐successional species regeneration but not the regeneration of the drought‐resistant light‐demanding species. The low representation of late‐successional trees species in the natural regeneration calls for active restoration intervention.

Plant extract-loaded bacterial cellulose composite membrane for potential biomedical applications

Bacterial cellulose (BC) has been extensively explored as biomaterial for various biomedical applications owing to its non-toxic nature and unique structural morphology and impressive physico-chemical and mechanical properties. However, its high production cost and lack of antimicrobial activity have restricted its large-scale production and therapeutic applications. Therefore, the current study is aimed to devise a strategy for low-cost BC production and develop its composite with bioactive materials to bless it with antimicrobial activity. Herein, 5 mm thick reticulated fibrous and highly porous BC was produced by utilizing the wasted rotten tomatoes as the production medium. The produced bacterial cellulose waste (BCW) (i.e., produced from wastes) was ex-situ modified with bioactive plant extract (PE) obtained from Euclea schimperi, and the bactericidal activity of the developed BCW/PE was evaluated against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli through disc diffusion and colony forming unit (CFU) count methods. The BCW/PE composite showed high bactericidal activities against S. aureus and produced clear inhibition zone whereas negligible activity was observed against E. coli, indicating its bactericidal activity mainly against the Gram-positive bacterium. Overall, this study illustrates that there is a huge potential for developing valuable biomaterials from food wastes and utilizing their liquid holding capabilities for value-added applications in medical and pharmaceutical fields.

Effects of stone mining on woody plant species diversity and selected soil properties in northern Ethiopia

BackgroundStone mining is one of the main livelihood activities in areas close to major cities in Ethiopia. Mining tends to make a notable impact on woody plant species and soil properties. Information regarding the effect of stone mining on woody plant species diversity and soil properties is limited in Ethiopia. It is also less known how people perceive the impact of stone mining on existing natural resource in the watershed after mining. Therefore, this paper analyzed the effect of stone mining on woody plant species diversity, selected soil properties and perception of nearby community on mining in northern Ethiopia.MethodsVegetation and soil sampling were conducted using 6.32 ha sample plots. Samples were randomly selected from mining and adjacent unmined areas. Species abundance, density, basal area, selected soil physical and chemical properties were analyzed. The differences in species diversity and soil physical and chemical properties between the mined and unmined areas were analyzed using independent t test. Household survey was also conducted to assess the view of the local people regarding the effect of mining on ecology.ResultsA total of 35 species representing 19 families in the mining site were recorded while 43 species representing 27 families were recorded in the unmined site. Abundance and density of species were higher in unmined than in mining areas. The most abundant species in the mining and unmined sites were Euclea racemosa subsp. schimperi, Senna singueana, Maytenus arbutifolia, Calpurnia aurea and Buddleja polystachya. Woody species diversity at mining (1.97) was significantly different from that unmined (2.49) site (p = 0.0005). Bulk density significantly varied between the mined (1.9 g cm−3) and unmined (1.38 g cm−3) sites (p < 0.0005). Furthermore, significantly higher TN and AvP was recorded at unmined areas as compared to the mining areas (p < 0.05). Discussion with communities is mandatory before deciding a site for mining. Respondents argued that mining negatively affects the vegetation and other resources that brought devastating effect on the downstream farms. The communities’ were recommended for immediate rehabilitation of abandoned lands to restore it and reduce the negative impact of mining.ConclusionsStone mining causes an adverse impact on plant species and soil physico-chemical properties. Discussion with communities at the planning stage, immediate restoration activities and monitoring are crucial to reduce the negative impacts of stone mining for further sustainable natural resources development and management.

Suitability of selected vegetable tannins traditionally used in leather making in Tanzania

Abstract The use of chromium salt has dominated in tanning industry worldwide due to its high versatility in quality leather production. However, Environmental concerns of chromium have shifted the interest of current research to chrome-free and greener chemical processing options. Vegetable tannins, especially when used in combination with some benign metals, have been proven to be environmentally safe and manageable, while producing good quality leather with similar shrinkage temperature as that of chromium tanned. As such, shortage of vegetable tannin supply necessitates characterization of non-commercialized sources locally available to feed cottage tanneries. In the present work, extracts from Acacia mearnsii, Acacia xanthophloea, Euclea divinorum and Euclea racemosa, leached by simple technique at 30–80 °C temperature range were characterized for extract yield, tannin, total flavonoid and phenolic contents, crosslinking ability as well as properties of tanned leather. Results indicate that at 50 °C extraction temperature, A. xanthophloea bark gave extract with properties similar to that of A. mearnsii (commercialized source of tannin). Extract from E. divinorum bark contain fairly less extract yield, tannin, total flavonoid and phenolic contents than that of A. mearnsii, but had good crosslinking ability and tanning performance similar to that of A. mearnsii when used in combination with Aluminium Sulphate [Al2(SO4)3]. The 2% Aluminium Oxide (Al2O3) equivalent was established to be optimal dose of Al2(SO4)3 for extract pre-treatment. E. racemosa barks have high extract yield, but very low crosslinking ability, making it not suitable as a tannin source. This work provides useful information on the potential source of tannins for cottage leather industries in Tanzanian and beyond.

Investigation of antioxidant and antimicrobial activities of Euclea schimperi leaf extracts

BackgroundBioactive components from medicinal plants are said to be responsible for the antioxidant and antimicrobial effects of plant extracts. It was the main purpose of this paper to evaluate the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant and antimicrobial activities of leaf extracts of Euclea schimperi.ResultsStrong evidence was found when a positive correlation was found between TPC or TFC and antioxidant power. To put it differently, TPC of the E. schimperi leaf extracts varied between 748.78 ± 3.11 mgGAE/100 g of dry extract (methanol) and 40.45 ± 0.66 mgGAE/100 g of dry extract (chloroform) while TFC varied from 3.306 ± 0.142 mgQE/100 g of dry extract (methanol) to 0.334 ± 0.002 mgQE/100 g dry extract (chloroform). Similarly, all extracts exhibited significant amount of antioxidant and antimicrobial activities. Ferric reducing power was ranged between 312.145 ± 1.542 mgAAE/100 g extract (methanol) and 48.177 ± 0.286 mgAAE/100 g (chloroform). DPPH radical scavenging activity (%) lied between 83.4% (methanol) and 58.5% (chloroform). The voltammetric analysis of the crude extract gave three different sharp peaks at the oxidation potential side. Finally, the reducing agent capacity of the extracts was further confirmed by synthesizing silver nanoparticles from AgNO3 solution and the plant crude extracts. Crude extracts of E. schimperi leaves showed various degree of antimicrobial activity towards different standard strains with mean zone of inhibition ranging from 0 to 20.67 mm. Both solvent leaf extracts of E. schimperi exhibited MIC ranging from 62.5 to 125 mg/mL towards most bacterial species.ConclusionsEuclea schimperi leaf extracts were found to contain high amount of total phenolic and small amount of flavonoid compounds which play a major role in controlling oxidation. In general, therefore, the results prove the effectiveness of the plant for its excellent antioxidant and antimicrobial activities. Accordingly, the positive values of the plant in traditional medicines have been confirmed.

Mixed-species allometric equations and estimation of aboveground biomass and carbon stocks in restoring degraded landscape in northern Ethiopia

Accurate biomass estimation is critical to quantify the changes in biomass and carbon stocks following the restoration of degraded landscapes. However, there is lack of site-specific allometric equations for the estimation of aboveground biomass (AGB), which consequently limits our understanding of the contributions of restoration efforts in mitigating climate change. This study was conducted in northwestern Ethiopia to develop a multi-species allometric equation and investigate the spatial and temporal variation of C-stocks following the restoration of degraded landscapes. We harvested and weighed 84 trees from eleven dominant species from six grazing exclosures and adjacent communal grazing land. We observed that AGB correlates significantly with diameter at stump height D30 (R2 = 0.78; P < 0.01), and tree height H (R2 = 0.41, P < 0.05). Our best model, which includes D30 and H as predictors explained 82% of the variations in AGB. This model produced the lowest bias with narrow ranges of errors across different diameter classes. Estimated C-stock showed a significant positive correlation with stem density (R2 = 0.80, P < 0.01) and basal area (R2 = 0.84, P < 0.01). At the watershed level, the mean C-stock was 3.8 (±0.5) Mg C ha−1. Plot-level C-stocks varied between 0.1 and 13.7 Mg C ha−1. Estimated C-stocks in three- and seven-year-old exclosures exceeded estimated C-stock in the communal grazing land by 50%. The species that contribute most to C-stocks were Leucaena sp. (28%), Calpurnia aurea (21%), Euclea racemosa (20.9%), and Dodonaea angustifolia (15.8%). The equations developed in this study allow monitoring changes in C-stocks and C-sequestration following the implementation of restoration practices in northern Ethiopia over space and time. The estimated C-stocks can be used as a reference against which future changes in C-stocks can be compared.

Floristic Composition and Community Analysis of Berbere Forest, Bale Zone, South East Ethiopia

The study was conducted on Berbere forest in Bale Zone of Oromia National Regional State, South east of Ethiopia with the objective of determining the floristic composition and community type of the forest. Systematic sampling method was used to collect vegetation data. Seventy two quadrat size of 400 m² (20 m x 20 m) for trees, shrubs and lianas and five 1 m² (1 m x 1 m) for herbs one at each corner and one at the center of the main plot were used. In each of these quadrants, all vascular plant species were collected and brought to National Herbarium, Addis Ababa University for identification. Vegetation classification was performed using PC-ORD software packages. Sorensens’s similarity coefficient and Shannon-Wiener diversity index were also used to detect similarities among communities and to compute species richness and evenness between the plant communities’ respectively. A total of two hundred one plant species in 157 genera and 65 families were identified from the forest. Fabaceae and Asteraceae are the dominant families in terms of species richness. Based on the results of vegetation classification, three plant communities (Terminalia brownie-Psydrax schimperiana, Warburgia ugandensis - Podocarpus falcatus, and Euclea racemosa subsp. schimperi-Combretum molle) were recognized and described. Ethnobotanical studies to explore indigenous knowledge on the diverse uses of plants, and sound management and monitoring as well as maintenance of biodiversity that promote sustainable use of the forest and its products are recommended.

The in vitro anthelmintic properties of browse plant species against Haemonchus contortus is determined by the polyphenol content and composition

The aims of the present study were to (a) evaluate the anthelmintic activity of 10 East African browse plant extracts, (b) examine their role in inhibition of Haemonchus contortus larval exsheathment, (c) establish relationship between inhibition of larval exsheathment and browse plant extract polyphenol composition. Acetone/water (70/30%) extracts of air dried leaves of Acacia etbaica, Cadaba farinosa, Capparis tomentosa, Dichrostachys cinerea, Dodonaea angustifolia, Euclea racemosa, Maerua angolensis, Maytenus senegalensis, Rhus natalensis and Senna singueana were used. The larval exsheathment inhibition assay (LEIA) was applied using H. contortus third stage larvae (L3) and browse plant extract concentrations of 0, 150, 300, 600, 1200μg/ml in phosphate buffered saline (PBS). Data were analysed using the PROC MIXED procedure of SAS. Polyvinylpolypyrrolidone (PVPP) was used to evaluate whether polyphenols were involved in L3 exsheathment inhibition. All browse plant extracts significantly (P≤0.001) inhibited larval exsheathment in a dose dependent manner. The dose required to inhibit 50% of the larvae (EC50) was highest in C. farinosa and lowest in E. racemosa and M. senegalensis. Significant differences (P<0.001) between the control and PVPP treated A. etbaica, C. tomentosa, M. angolensis, R. natalensis and D. cinerea indicates that larval inhibition was largely due to non-phenol compounds. For E. racemosa, M. senegalensis, D. angustifolia and S. singueana, PVPP treatment reversed inhibition activity and in these extracts, inhibition was mostly attributable to tannin and other polyphenols (kaempferol, quercetin and myricetin based glycosides). Overall, the browse plant extracts have anthelmintic property against H. contortus and larval inhibition resulting from the presence of phenolic and non-phenolic compounds.

Preference of goats (Capra hircus L.) for tanniniferous browse species available in semi-arid areas in Ethiopia.

The objectives were to determine browse species preference of goats using dry matter intake (DMI) as a proxy, to compare preference when offered in combination with polyethylene glycol (PEG) and to establish relationships between browse species intake and chemical compositional data. Air-dried leaves of Acacia etbaica, Cadaba farinosa, Capparis tomentosa, Dichrostachys cinerea, Dodonaea angustifolia, Euclea racemosa, Maerua angolensis, Maytenus senegalensis, Rhus natalensis and Senna singueana were used. Two cafeteria trials, each lasting 10days, were conducted using four local mature male goats of 2-2.5years receiving a daily ration of grass hay (4% of body weight) and 200g wheat bran. In trial 1, goats were offered 25g of each browse species for a total of 30min with intake, time spent on consumption and the number of visits to specific browse species recorded at 10-min intervals. In trial 2, the same procedure was followed except that 25g of PEG 4000 was added to the daily wheat bran ration. Crude protein and neutral detergent fibre in browse species ranged from 69.0-245.5 to 159.8-560.6g/kg dry matter (DM) respectively. Total phenols and total tannins contents ranged between 3.7-70.6 and 2.5-68.1mg tannic acid equivalent/g DM, respectively, and condensed tannins 1.7-18.4 Abs550nm /g DM. Preference indicators measured in the first 10min of browse species intake differed significantly among browse species and with PEG (p<0.0001). Principal components explained 69.9% of the total variation in browse species DMI. Despite the high tannin levels, D.cinerea, R.natalensis and A.etbaica were the most preferred species regardless of PEG presence. Tannin levels at the observed browse species DMI did not determine preference, instead, preference appeared to be based on hemicellulose. Determining browse species preference is essential to exploit them to improve nutrient utilization and control parasites in goats.

Light availability drives tree seedling success in a subtropical coastal dune forest in South Africa

In subtropical coastal dune forests of South Africa, the microenvironment of tree seedlings is largely influenced by a pervasive understorey woody herb, Isoglossa woodii. We examined whether the additional shading by I. woodii explains the competitive response of tree seedlings from these forests. Seedlings of four common mid- to late-successional tree species (Diospyros natalensis, Euclea racemosa, Sideroxylon inerme and Apodytes dimidiata) were grown at three densities of I. woodii in a common garden experiment under greenhouse conditions. The seedlings were grown at 1.6% and 13.5% of full sunlight and supplied with 1% and 10% nitrogen in half-strength Hoagland's nutrient solution. Total biomass and biomass allocation parameters were used to measure the competitive response of the seedlings. Seedlings attained maximum biomass at high light and high nutrient levels and showed species- and light-specific responses to biomass of I. woodii neighbours. Seedlings' allocation to roots increased with increasing light levels but decreased at higher nutrient levels. The leaf mass fraction (LMF) response to light and nutrient levels was opposite to that shown by root allocation. Specific leaf area (SLA) and leaf area ratio (LAR) decreased with increasing light conditions but were not responsive to manipulation of nutrients. The presence of I. woodii neighbours reduced LMF whilst the responses of SLA to neighbours depended on the light level and species. Leaf trait responses to manipulation of light conditions, I. woodii neighbour density and soil nutrient concentration are complex but overall demonstrate an overwhelming role of light in influencing seedling establishment in coastal dune forests. The competitive response of these seedlings to low irradiance reiterates the notion of phenotypic clustering at the seedling stage amongst shade tolerant tree species, which promotes seedling persistence and gradual transition into the tree layer. Our results highlight the role of additional understorey shading by the herb stratum in influencing tree recruitment dynamics and ultimately tree community structure in many of Africa's tropical lowland forests.

Removal of hexavalent chromium from aqueous solutions using barks of Acacia albida and leaves of Euclea schimperi

Removal of hexavalent chromium ions (Cr(VI)) from aqueous solutions by adsorbents prepared from barks of Acacia albida of Fabaceae family and leaves of Euclea schimperi of Ebenaceae family has been studied by batch adsorption technique. Double-beam UV-visible spectrophotometer was used to monitor the concentration of Cr(VI). The influence of contact time, initial chromium ion concentration, pH and adsorbent dose on the efficiency of adsorption process was studied. Among the studied parameters, pH was found to be the most influential. At the optimum pH (pH 2), 98.47 and 97.39 % removal of Cr(VI) was achieved using the adsorbents prepared from barks of A. albida and leaves of E. schimperi, respectively. After determining the optimal conditions for maximum adsorp- tion, the applicability of the biosorbents was tested on real samples. The results indicate that these adsorbents can be employed as low-cost alternatives to commercial adsor- bents for the removal of Cr(VI) from effluents. Adsorption isotherms and kinetic parameters were also studied. The results showed that the adsorption of Cr(VI) by these adsorbents follow Langmuir adsorption isotherm. The kinetics of the adsorption process follows the pseudo-sec- ond-order kinetic model.

Evaluation of the adaptability and response of indigenous trees to assisted rehabilitation on the degraded hillsides of Kuriftu Lake Catchment (Debre Zeit, Ethiopia)

Removal of trees and shrubs from hillsides exposes a site to erosion that threatens soil aggregation and stability. The present study aimed at evaluating the performance of five indigenous tree species in rehabilitation of degraded hillsides of Kuriftu Lake Catchment and the role of water harvesting structures. Adaptability varied by tree species and water harvesting structures significantly augmented seedling establishment for some tree species. Height of Acacia abyssinica planted on steeper slopes (18%–27%) without infiltration pits was lower than for conspecifics planted with infiltration pits. Dodonaea angustifolia was proved to be best adapted to the site and showed no need for water harvesting regardless of planting position across the degraded hillside. Planting of Acacia seyal should be restricted to gentler slopes (0–17%) with infiltration pits: tree height declined significantly on steep slopes without infiltration pits. Olea africana performed better on gentle slopes with pits but also grew well on steeper slopes with pits. Euclea schimperi was proved to be least effective of the species evaluated in this study.

Density Effects of a Dominant Understory Herb, Isoglossa woodii (Acanthaceae), on Tree Seedlings of a Subtropical Coastal Dune Forest

Suppression of tree seedlings by the understory is an important ecological filter with implications for tree diversity and dynamics. In a greenhouse competition experiment, we used seedlings of four canopy species from coastal dune forest (Diospyros natalensis, Euclea racemosa, Sideroxylon inerme and Apodytes dimidiata) to examine the relative competitive effects of the dominant understory herb Isoglossa woodii on seedling performance. We manipulated I. woodii density, light and nutrient levels and measured growth responses. Total seedling biomass decreased with density of I. woodii. The magnitude of biomass suppression with competitor density was similar among tree species. Consequently there was no discernable hierarchy of competitive ranking among tree species. The relative growth rate of seedlings decreased at higher densities of I. woodii and increased at higher nutrient levels but was unaffected by variation in light conditions. Aboveground biomass decreased at higher densities of I. woodii and at higher light levels but increased at higher nutrient levels. Size asymmetric competition for light and nutrients may be the major driver of aboveground interactions between tree seedling and I. woodii. While tree species showed no hierarchy of competitive ability their seedlings exhibited equivalent responses to competition from an understory dominant, permitting species coexistence and the maintenance of species diversity.

Genetic structure of Euclea schimperi (Ebenaceae) populations in monsoonal fog oases of the southern Arabian Peninsula

Euclea schimperi, a widespread Afromontane shrub or tree, occurs in the Arabian Peninsula in fragmented, semi‐evergreen or evergreen woodland refugia in wet escarpment localities of the western and southern mountain chains. In the southern coastal mountains, the (semi‐) evergreen woodland with E. schimperi is close to its ecological limit and consequently today very rare, with the exception of the monsoonal fog oases of east Yemen and south Oman in the central south coast of the Arabian Peninsula. Due to the steep precipitation gradient from the centre to the western edge in this monsoon affected area, E. schimperi is found in two different habitat types: in continuous woodland belts in the Hawf and Dhofar mountains, and in isolated, scattered woodland patches in the Fartak Mountains. Ten populations (138 individuals) from across the southern Arabian distribution area of the species were analysed using chloroplast microsatellites and AFLP fingerprinting to a) reconstruct the phylogeographical pattern of E. schimperi on the southern Arabian Peninsula and b) to evaluate the consequences of population fragmentation on the genetic diversity harboured in isolated patches vs cohering stands. Phylogeographical reconstructions show that the distribution area of E. schimperi in the southern Arabian Peninsula is characterised by a geographical split that separates the southwestern populations (representated by material from Jabal Eraf and Jabal Uthmar), from the southcentral populations, which themselves are split from each other into a western (Ras Fartak) and an eastern refugium (Hawf/Dhofar). The analysis of the within‐population genetic diversity in E. schimperi populations resulted in a slightly, but not significantly higher genetic variation in small and isolated woodland patches (HS=0.302) compared to larger, cohering stands (HS=0.291).