Search

Acacia sieberiana DC. Small to medium tree, in wooded savannah, open forest, thicket, and grassy savannah; also wet places. C.N.: mussongue, musonge (kb). Uses: firewood, medicinal. Conservation: LC (Costa et al. 2009, 2019) F.Monteiro 799 (LUAI, LISC), Published as part of Monteiro, Francisca, Costa, Esperança Da, Kissanga, Raquel, Costa, José Carlos & Catarino, Luís, 2022, An annotated checklist of the vascular flora of Quiçama National Park, Angola, pp. 1-67 in Phytotaxa 557 (1) on page 31, DOI: 10.11646/phytotaxa.557.1.1, http://zenodo.org/record/6985699, {"references":["Costa, E., Dombo, A. & Pedro, M. (2009) Plantas Ameacadas em Angola. Centro de Botanica, Universidade Agostinho Neto, Luanda, 154 pp."]}

The present study focused on Physicochemical, proximate and mineral analysis of some underutilized wild edible seeds (Parkia biglobosa,Prosopis africanumandAcacia sieberiana) used as condiments in Nigerian traditional soup and consumed by different tribal communities across the country. The seed samples were all pulverized and their properties determined appropriately. The physicochemical properties of the three seed samples were comparable with each other and the values obtained were similar and fell within the range observed for similar seeds and powdered samples used as condiments or for industrial purposes. Swelling and solubility profiles of the seed samples were quite high and reflected the high water absorption capacity of the pulverized seeds. Proximate analysis of the seed samples revealed a high protein content especially forP. africanumandA. siberianawhileP. biglobosahad a high fat and carbohydrate content. Elemental analysis of the pulverized seeds was also carried out to determine the mineral contents and it was observed that the concentration of the essential elements were within safety limits while the heavy metals were very low with lead and chromium absent in two of the samples which was an indication of little or no toxicity of the seeds. The results of the various analysis carried out on the seed samples p\shows that all the three (3) study seeds are safe for consumption. These lend credence to their use as condiments and indicates that they can be further explored for other uses in the food industry.

Coffee production with shade trees is important to improve growth and quality of coffee, sustain and restore agroecology and nature based agroforestry practices. The trial was conducted at Mechara Agricultural Research Center (on station) in DaroLebu District of West Hararghe Zone, Oromia, Ethiopia. The study was intended to evaluate the influence of coffee shade trees on growth performance, yield and quality of coffee (Coffea arabica L.) under the canopy of Erytherina absinica, Cordia africana and Acacia sieberiana. The design was Randomized complete block design with three replications. The outcome had been observed a significant value at (p0.05) probability level and highly significance value at (p

The study was aimed at evaluating the seeds of a leguminous plant, Acacia sieberiana DC as an alternative source of dietary plant protein for broilers. Five experimental diets containing 0 (control), 5, 10, 15 and 20% Acacia sieberiana seeds (ASS) were formulated and fed to 5 groups of birds during starter (0 - 4 weeks), grower (5 - 8 weeks) and finisher (9. -12 weeks) periods respectively. There were 3 replicates per treatment, with 10 birds per replicate. At the end of the experiment, average weekly live weight gains of 128.90 ± 24.17, 122.68 ± 25.09, 112. 79 ± 22.83, 96.40 ± 21.53 and 99.56 ± 21.53g were obtained for the birds on 0, 5, 10 and 20% ASS inclusion respectively. The average weekly feed consumption values were 413.47 ± 63.63, 408.59 ± 63.82, 304.60 ± 61.70, 347.96 ± 58.0 and 352.83 ± 59.76g for the birds on O, 5, 10, 15 and 20% ASS respectively. The feed efficiencies were 0.289 ± 0.03, 0.272 ± 0.03, 0.264 ± 0.03, 0.248 ± 0.03 and 0.253 ± 0.03 for the birds on 0, 5, 10, 15 and 20% ASS respecfrre!y. The data revealed that in general, the birds on 0, 5 and 10% ASS inclusion performed better (PC < .05) than birds on 15 or 20% ASS. Results of carcass evaluation show that the gizzard, lungs and heads of the control birds had significantly (PC < .05) higher weights than those of birds on 15 and 20% ASS. From these results it can be concluded that up to 10% ASS could be incorporated into poultry diet without deleterious effect on broilers. Keywords: Broilers, Acacia Seeds, Performance, Carcass Evaluation

Understanding the factors controlling tree seedling recruitment is an integral research priority for savanna ecosystems, particularly for the management of woody plant encroachment. We investigated the effects of increased nutrients, fire and grazing on the survival, growth and biomass of Acacia sieberiana using a completely randomized experimental design in the greenhouse. We simulated a typical savanna microhabitat by planting a common savanna grass species, Eragrostis curvula, with seedlings of A. sieberiana. The trees and grasses were allowed to establish for 12 weeks. Thereafter, treatments of fertilizer (100 kg N/ha), simulated grazing and fire were applied. Weekly measurements of relative growth rate (RGRheight and RGRdiameter) were recorded. At the end of 24 weeks, survival, total above- and below-ground biomass, and key functional traits of the trees (specific leaf area and average thorn length) were recorded to assess differences in tree performance. We found that fertilization was beneficial to the grass only, increasing their total biomass. While, the direct removal of grass biomass by grazing in our study revealed no main (statistical) effect on tree seedling growth, we observed decreased survival of tree seedlings with higher grass biomass. Fire increased the tree seedlings’ investment in shoot growth and stem diameter. However, in the absence of grass competition, there were no differences in the post-fire allocation of the resprouting tree seedlings. Higher grass biomass was found to result in decreased specific leaf area of tree seedlings. We conclude that grass competition is important for controlling the encroachment of A. sieberiana.

Les espaces pastoraux subissent des régressions et des conquêtes de par le monde. Ceux-ci occasionnent la diminution assez large de la quantité et de la qualité des fourrages encore disponibles. Cette étude a été réalisée dans le but d’évaluer qualitativement les espèces fourragères présentes au sein du département de la Bénoué. La méthode utilisée pour l’identification des espèces fourragères (herbacées et ligneuses) se base sur les différents entretiens menés auprès des éleveurs de ruminants, par le suivi des bovins, caprins et ovins au pâturage et par l’utilisation des clés d’identification disponibles. Les résultats montrent que les zones de pâturages existantes, diffèrent en qualité floristique et selon la localité où l’on se retrouve. En plus, plusieurs essences fourragères existent et appartiennent à environ 41 espèces. Parmi la vingtaine d’espèces fourragères appréciées par le bétail, 05 ligneuses le sont encore plus (Prosopis africana, Daniella oliveri, Acacia sieberiana, Stereospermum kunthianum et Balanites aegyptica). Il en est de même des 02 herbacées : Acroceras amplectens et Pennisetum pedicellatum. Plus d’une dizaine se retrouve en voie de disparition/menacées de nos jours. Si rien n’est fait, dans quelques années on observera une diminution de la richesse floristique en termes de ressources fourragères dans les différentes localités. Par ailleurs, une étude portant sur les éléments nutritifs et une étude quantitative de ces espèces fourragères rencontrées doivent être menées, pour mieux enserrer les espèces à conserver et les meilleurs espaces offrant de meilleures ressources fourragères.Mots clés : Zones de pâturage, richesse floristique, éleveurs de ruminants, clés d’identifications. English Title: Qualitative assessment of fodder species present in the Bénoué division (North Cameroon)Pastoral land (areas) worldwide are undergoing rapid decline as a result of urbanization (development). This often leads to a large decrease in the quantity and quality of available fodder. This study was aimed at evaluating quantitatively the various fodder species present within the Bénoué division. The method used for identification of fodder species (herbaceous and ligneous) was through interviews (surveys), conducted with animal-grazers (breeders) pasturing their flocks (cattle, goats and sheep) in the field and using available keys for fodder for pinpointing. The existing pastoral areas (zones), varies in quality and quantity of flora depending on the location where it is found. Several fodder species exist, belonging to about forty-one (41) classes of species. Among the twenty (20) fodder species best valorized by livestock, five (5) ligneous are most preferred (Prosopis africana, Daniella oliveri, Acacia sieberiana, Stereospermum kunthianum et Balanites aegyptica). As for the herbaceous, same is true for two (2) species, Acroceras amplectens et Pennisetum pedicellatum. More than a dozen species happen to be endangered. Thus, if nothing is done in a few years in order to conserve and preserve these endangered species they might become threatened as a result of gradual reduction in terms of their flora abundance within the different localities. In addition, a study relating to the nutritive elements and a quantitative study of these fodder species met must be undertaken, for better enclosing the species to be preserved and best spaces offering of better fodder resources.Keywords: Pastoral areas, flora abundance, livestock grazers, keys of identifications.

Trypanosomiasis has been recognized as a scourge in sub-Saharan Africa for centuries and chemotherapy of the disease still remains unsatisfactory. This study is to explore an alternative source of antitrypanosomal agents from the stem bark of four Acacia species; Acacia nilotica, Acacia sieberiana, Acacia geradii and Acacia hockii. Dried stem bark of each plant was pulverized and extracted with 98% methanol by maceration. Phytochemical screening was carried out followed by in vitro testing of extracts on the motility of Trypanosoma congolense maintained in Ringer solution. Motility assessment of trypanosome was carried out after exposure with varied concentrations of the extracts for 2 hours. Thereafter, infectivity test was carried out using albino mice. Seventy-two mice, divided into twenty-four (24) groups of three animals were each inoculated with 100µl of the mixture containing the varying extract concentrations intraperitoneally. Berenil was used as standard drug control. Establishment of infection and subsequent Parasitaemiawere monitored in the animals for 60 days. The Phytochemical assay revealed the presence of anthraquinones, tannins, glycosides, cardiac glycosides and terpenes in all the extracts. Saponin was only present in Acacia nilotica and Acacia geradii. Incubation of parasites with each of the four acacia species recorded cessation in parasite motility which was concentration dependent. The highest concentration 20 mg/ml showed the highest effect within fifteen (15) minutes of incubation which was similar to the Berenil incubated control. However, lower doses (0.005 and 0.00005) mg/ml did not show difference from the non extract incubated negative control. Incubation of T. congolense with Acacia nilotica, Acacia sieberiana, Acacia geradii and Acacia hockii at 20, 10 and 1 mg/ml inhibited the ability of the parasites to establish infection in the albino mice as compared the standard control drug. The results indicate that the methanolic stem extracts of the four acacia species possess antitrypanosomal activity with potentials for the treatment of trypanosomiasis.

Partial migration is a common movement phenomenon in ungulates, wherein part of the population remains resident while another portion of the population transitions to spatially or ecologically distinct seasonal ranges. Although widely documented, the causes of variation in movement strategies and their potential demographic consequences are not well-understood. Here, we used GPS telemetry data and individual-based photographic surveys to describe evidence for the partial migration of giraffe (Giraffa camelopardalis) in the tropical savanna habitat of Murchison Falls National Park, Uganda. Seasonal movements in giraffe have been described but have not been systematically investigated within the framework of partial migration. We characterized movement behaviors of eight female GPS tracked giraffe across one full year using a model-driven approach of net-squared displacement metrics. To further evaluate these space use patterns at the population-level, we used closed robust design multi-state capture recapture models derived from individually based photographic surveys collected seasonally over three years. We also characterized environmental conditions associated with seasonal space use by conducting ground-based vegetation surveys and analyzing remotely sensed phenology data. Our results from both individually based telemetry models and population-level multi-state models suggest intra-population variation in seasonal space use strategies with three dominant movement classes: (1) Residents in deciduous savanna characterized by Acacia sieberiana, Acacia senegal, Harrisonia abyssinica, and Crateva adansonii in the far western end of the park. (2) Residents in the broadleaf savannas characterized by Pseudocedrela kotschyi, Stereospermum kunthianum, Termalia spp., and Combretum spp. in the central sector of the park (3) Male-biased migrants that transitioned seasonally between the acacia savanna in the wet seasons and the broadleaf savanna in the dry seasons. Our results offer insights into how giraffe navigate spatiotemporally dynamic environments at both individual and population levels, providing ecological mechanisms for the emergent population dynamics of these large-bodied topical browsers.

Pastoral nomadic communities of East Africa’s drylands are gradually shifting towards a sedentary type of production. However, successful animal production under such settings demands for integrated on-farm management of the various animal feed resources. The objective of this study was to characterize feed resources of goats in the pastoral area of Karamoja sub-region, a dry land area in northeastern Uganda. Structured interviews were conducted involving 300 randomly selected households. Results revealed seventy plant species distributed in 31 families were fed to goats. The species were dominated by browses (trees and shrubs) 54%; herbs 21%; grasses 19%; climbers and hedges 5%. Balanites aegyptica, Grewia similis, Acacia sieberiana, Acalypha fruticosa, Acacia albida and Cadaba farinosa were the most frequently mentioned browse species. Farmers also use these species for other purposes notably building, human and livestock medicine, fencing, firewood and as vegetables during the dry season. Browses were available throughout the year unlike grasses and crop residues that were available seasonally. Since browses were available throughout the year in addition to being multipurpose, it is recommended that current efforts to actualize a sedentary lifestyle among Karamoja pastoralists integrate the planting and management of the most reported browse species in this study.

A study on effect of age, sex and seasonal variation in forage preference of camel was conducted in the Sudano-Sahelian zone of north western Nigeria. A total number of 12 camels were used in the study. Data were collected at an interval of 5 min for each category of animal for 3 consecutive days in dry and rainy seasons using scan sampling method. Based on the observation, the number of plants preferred in this study by young camel calves was less than that preferred by matured camel. Matured animals consume mostly diversified, thorny and taller plant species which might not be easily accessed by the camel calves. Leptadania hastata was found to be the most preferred forage during the rainy season, while Ziziphus mauritiana was the preferred forage during dry season with mean feeding time of 87.33 and 46.66 min/day, respectively; while the least preferred forage during the rainy and dry seasons were Acacia sieberiana and Bauhinia rufescens with mean feeding time of 0.11 and 15.00 min/day, respectively. Browse species found in the study area are extremely important as feed for camels. Key words: Camel, preference, forage, grazing.

During the dry season, most plants and grasses dry up and ruminants are left with fewer plants to graze on. The plants available during such periods have relatively lower moisture contents and higher antinutritional factors because of the dry nature of the soil and prevalent atmospheric conditions. Increased levels of antinutritional factors above acceptable values, could have a detrimental effect on the metabolic and health status of animals grazing on such plants. This research work sought to determine the phytochemicals present and the levels of some antrinutritional factors in plants (Acacia senegal, Parkia biglobosa, Anogeissus leiocarpus, Acacia sieberiana, Vitellaria paradoxum, Tamarindus indica, Ficus carica, Ziziphus spinachristi Dichrostachus cinerea, Ziziphus mucronata) commonly grazed upon by ruminants in this region, to educate farmers and policy makers on the safety of these plants for ruminant nutrition. The plants were collected and identified, while phytochemical and anti-nutritional profiles were analyzed using standard spectrophotometric procedures. Quantitative antinutritional factors analysis showed that the level of oxalate varied from 15 to 180 mg/100 g, phytic acid from 23.51 to 53.41 mg/100 g and tannins from 0.486 to 1.850 mg/100 g, which are within internationally accepted permissible limits. Results of qualitative phytochemical analysis showed that flavonoids, tannin, cardiac glycosides and steroids were present in all the plants, while anthraquinones were absent. The results suggest that the browse plants in this location contain anti-nutrients at relatively low levels which make these plants safe for ruminant consumption. Key words: Plants, antinutritional factors, phytochemicals, grazing ruminants

Although the rumen microbiome has been reported to synthesize a rich source of symbiotic enzymes (exocellulase, endocellulase, hemicellulase and cellobiase), the digestion of tropical C4 grasses and browses by ruminants is still limited. Therefore, this study aimed to unveil potential fibrolytic microbial ecosystems from giraffe, kudu, impala and consortia (A1 [giraffe + kudu], A2 [giraffe + impala], A3 [kudu + impala], and A4 [giraffe + kudu + impala]) browsing tanniferous plants, which can be used to improve forage utilization in domesticated goat. Crude protein enzyme extracts (CPZ) from fresh faecal samples were precipitated by 60% ammonium sulphate and assayed for exocellulase, endocellulase and hemicellulase by incubating with crystalline cellulose, carboxymethyl cellulose and xylan at 38 °C with optimum pH of 5.5 to 6.5 for 1, 2, and 48 h, respectively. Enzyme specific activities were defined as μg of reducing sugar/mg CPZ. In vitro fermentation study was done by transferring 33 mL of fresh faecal inoculum into 67 mL of salivary buffer containing 1 g Acacia sieberiana and incubating for 72 h at 38 °C. Apparent degradability (APDeg), true degradability (TD), neutral detergent fibre degradability (NDFdeg), acid detergent fibre degradability (ADFdeg), microbial yield (MY), metabolizable energy (ME) and total gas emitted (Gas) were measured. Exocellulase activities were higher (P

This study aims to determine the composition and thermal behavior of three acacia gums, namely, Acacia sieberiana, Acacia gerrardii, and Acacia tortilis (ATR) from Sudan. The results showed high percentages of carbon and oxygen and a low percentage of sulfur in all samples. Thermal behavior was studied using differential scanning calorimetry and thermal gravimetric analysis. Differential scanning calorimetry thermal profiles showed early intensive endothermic peak at temperature 100°C (peak temperature) associated with negative enthalpy and specific heat values, and intensive exothermic peak at temperature about 300°C (peak temperature) associated with positive specific heat and enthalpy values for all samples. Thermal gravimetric analysis curves showed three decomposition stages for both A. sieberiana and ATR gums and two decomposition stages for A. gerrardii; the major decomposition occurred at temperature around 280°C for all samples. The overall results of the present study reveal that all gum samples studied are thermally stable, and they possess the potential to be used as food modifiers.

In the animals in general and nonhuman primates in particular self-medication has been widely reported; however, little is still known about the pharmacological activity of the extracts present in their daily diet. Thein vitroantibacterial activity of the stem, root bark, and leaf extracts of three selected plants on which yellow baboons feed in an unusual manner in Mikumi National Park, Tanzania, was evaluated. Crude plant extracts were tested against Gram positive and Gram negative bacteria of medical and veterinary importance employing a modified agar well diffusion method and Minimum Inhibitory Concentration (MIC) technique. The lowest MIC value for Gram positive strains was 0.31 mg/ml demonstrated byCassia abbreviatassp.abbreviataagainstStaphylococcus aureus(ATCC 25923). The highest susceptibility to the ethanol plant extracts was exhibited byPseudomonas aeruginosa,Escherichia coli,andStaphylococcus aureus,examples of microbes that affect both human and nonhuman primates. These findings demonstrate that the plant extracts fromSterculia africana,Acacia sieberiana,andCassia abbreviatassp.abbreviatahave antibacterial activity and may be used as feed for their prophylactic benefits. Remarkably, the lowest MIC of 0.16 mg/ml was only 16-fold weaker than Gentamicin, a standard drug.

Because of technical difficulties in measuring soil properties at a large scale, little is known about the effect of soil properties on the spatial distribution of trees in grasslands. We were interested in the associations of soil properties with the phenomenon of tree encroachment, where trees increase in density at the expense of grasses. The spatial variation of soil properties and especially soil texture may modify the properties of hydraulic conductivity, and the availability of soil water and mineral nutrients, which in turn may affect the spatial distribution of encroaching trees. Through the development of a geophysical method (Slingram) using an electromagnetic device EM38 and Bayesian inversion, we were able to accurately map soil electrical conductivity (EC) of a Luvisol in a grassland of South Africa. EC measured at the 08 to 2m depth on a 15ha area is a proxy for clay content and was correlated with the spatial distribution of four size classes of the encroaching Acacia sieberiana. Tree location (all sizes considered) was significantly correlated with EC. Tall acacias (>3m height) were totally absent from patches with EC >24mSm(-1). For all other size classes from medium trees to seedlings, tree density decreased with increasing EC. This suggests that high clay contents at depth associated with high EC values may prevent the establishment and/or survival of trees and influence the spatial distribution of A.sieberiana. This result also shows that geophysical tools may be useful for demonstrating important ecological processes. Copyright (c) 2014 John Wiley & Sons, Ltd.

Termites are considered to be ecosystem engineers because they modify their biophysical environments. We tested the effects of soil-nutrient alteration in termite-enriched soils compared with termite-free open savannas. We also tested whether non-nutrient alterations (soil disturbance) induced by termites led to changes in tree-seedling growth. Soil samples taken from termite-enriched soils and adjacent open savanna sites in KwaZulu-Natal, South Africa were analyzed for nitrogen, pH, organic carbon and water-holding capacity. Seeds from three dominant tree species, Acacia sieberiana, Celtis africana and Ziziphus mucronata, were grown in soils taken from termite-enriched soils and adjacent savannas. Overall, organic carbon and nitrogen content were higher in termite-enriched soils than in adjacent savannas. We found that these differences in nutrients did not directly affect seedling growth rates or final height. However, C. africana had increased growth rates in compacted termite-enriched soils, while A. sieberiana seedlings were taller in non-compacted soils. We conclude that the indirect effects of disturbance by termites may be as important as the direct effects of increased nutrients for growth of savanna trees.

Organic matter degradation of Acacia nilotica, Acacia sieberiana, Annana senegalensis, Balanites aegyptiaca, Cassia sieberiana, Combretum leati, Faidhebia albida, Maerua angolensis, Prosopis africana and Vitex doniana using two different techniques: (i) the in sacco nylon bag degradation and in vitro gas production techniques. Samples were incubated in sacco and in vitro for 24, 48, 72 and 96 h. In sacco and in vitro OM degradation kinetics were described using the equation Y=a+b(1-e -ct ). The dry matter (DM) and crude protein (CP) were relatively high ranging from 934.00 to 984.60 g Kg -1 DM and 122.50 to 174.80 g Kg -1 DM in Cassia sieberiana and Acacis nilotica had the highest value (216.60 and 910.30 g Kg -1 DM for as and organic matter (OM) The highest value for neutral detergent fibre (NDF) and acid detergent fibre (ADF) was observed in Vitex doniana. The acid detergent fibre was generally high ranging from 86.40 to 144.70 g Kg -1 DM. The OM disappearance increases with increasing incubation time in all the browse forages ranging from 28.56 in Balanites aegyptiaca at 24 h to 76.53 in Combretum leati at 96 h. The OM degradation constant (a, b, a+b, lag T and ED) were all significantly different (P

The variation among tree species in their sapling responses to disturbances such as fire, herbivory and grass competition results in different probabilities of recruitment into savanna communities. A sapling’s ability to persist under these disturbances depends on its investment in growth, defences and stored reserves, based on soil available nutrients. We examined the survival and investments in growth and defence of the saplings of four Acacia species, in the presence of competing grasses, under varying soil nutrient levels. We also have evaluated the effects of fire on these saplings. We performed the study in a greenhouse at the UKZN Botanical Garden, Pietermaritzburg, South Africa. Nutrients had no significant effect on the survival of tree saplings regardless of fire treatment. Only 22.5 % saplings survived after fire treatment compared with 84 % of control saplings. Acacia sieberiana showed the highest resprout survival, while A. karroo did not survive the fire. Growth in A. nigrescens increased only at intermediate levels (0.5N, 1N) of the fertiliser provided. Condensed tannins in A. karroo also decreased at an intermediate level (1N) of fertiliser. Resprouts grew faster in stem height than in diameter and did not invest in chemical defences. No treatment had an effect on the proportion of root and shoot dry biomass. In conclusion, African acacias are not dependent on soil nutrients for their survival and differ in their ability to resprout after fire. Intermediate levels of nutrient availability are beneficial to sapling development as opposed to zero and high nutrient levels, due to nutrient-grass dynamics. The benefits of post-fire grass removal and an increase in nutrients can be effectively utilised by only a few species of acacias.

An experiment was conducted to determine preference intake and relative palatability indices of Acacia karroo, Acacia nilotica, Acacia tortilis, Acacia sieberiana and Acacia rhemniana in sheep and goats using a completely randomized design. The size of Experimental Farm from which the browses were harvested was 1842.75 ha. The leaf samples were randomly collected from various young trees. The samples were analysed for proximate composition, measured for intake and relative palatability indices of sheep and goats. Dry matter (DM) content ranged from 917.4 to 936.8 g/kg DM and organic matter from 822.9 to 892.2 g/kg DM. All acacia species contained crude protein content (CP) of more than 7–17% required for grazing animals. The content of neutral detergent fibre (ADF) and acid detergent fibre ranged from 372.8 to 658.1 and 150.0 to 464.6 g/kg DM, respectively and were significantly (P < 0.05) different among the species. All of the acacia species had low levels (0–5.57 g/kg DM) of condensed tannins. The intakes of all feeds except A. karroo and A. rhemniana were high in both sheep and goats. The leaves from A. sieberiana had the highest palatability indice (Pi) while those of A.rhemniana had the lowest Pi in both sheep and goats. It was concluded that there was an effect of acacia species on intake and relative palatability indices. Species A. sieberiana, A. nilotica and A. tortilis have potential as livestock fodder, based on moderate to high CP value, low ADF, low tannins, high intake and relative palatability indices.

As with many grasslands globally, the Highveld grasslands of South Africa are tree-less, despite having a climate that can support tree growth. Models predict that fire maintains these grasslands. The question arises as to why fire-tolerant savanna trees do not survive in these ecosystems? Savanna tree survival in mesic areas is restricted by demographic bottlenecks, specifically limitations to sapling-escape from fire. It was hypothesised that ancient highly leached soils from grassland areas would prevent saplings from growing fast enough to escape the fire-trap. Growth rates of savanna tree seedlings (Acacia karroo Hayne and Acacia sieberiana Burtt Davy) were measured in a common garden experiment using soils from ten sites collected along a savanna-grassland continuum. Soils from grassland sites were relatively nutrient-poor compared to those from savannas with lower pH, and associated cations. A. sieberiana growth rates responded to pH and these nutrients, whereas A. karroo growth was less strongly linked to specific nutrients. Even so, both species accumulated more biomass when grown in soils from savanna sites compared to grassland sites. An exception was a low elevation low nutrient savanna site that resulted in poor growth, yet sustains high tree biomass in situ. Differences between growth in grassland and savanna soils were small. They may contribute to, but are unlikely to explain, the treeless nature of these grasslands.

Aims In spite of the importance of African acacias in vegetation succession and provision of goods and services, little is known about life-history variations within and among species. Much of the work done on African acacias has focused on seed predation and germination and seedling establishment, especially of Acacia tortilis, Acacia nilotica and Acacia karroo. The primary aim of the present work is to investigate differences in the demography of Acacia polyacantha and Acacia sieberiana and the relationship between life-history characteristics and population size. A secondary objective is to assess how fire, an important ecological factor in savanna vegetation, might modify the growth and demographic dynamics of the two acacias. Methods The study was conducted at the Makeni savanna plot in central Zambia, southern Africa. Seedling emergence from both non-scarified and scarified seeds sown at different times in the wet season and the fate and growth of seedlings and saplings were monitored over a period of 4 years. Annual growth of permanently marked sample trees in annually burnt and fire-protected blocks was recorded over a 6-year period (2002–08) in order to assess inter-specific differences and how fire modifies tree growth patterns. Censuses of natural saplings and trees were conducted periodically in sample blocks to determine recruitment into these life-history stages. Important findings Seedling emergence and sapling survival rates were much higher in A. sieberiana than in A. polyacantha. However, both seedling and sapling growth rates were higher inA.polyacantha than in A. sieberiana but tree growth rates were similar in the two species. Under fire protection tree growth was significantly influenced by tree size and year while under annual burning only tree size significantly affected tree growth. The dominance of A. sieberiana over A. polyacantha at the study site was attributed to higher seedling emergence rate, higher sapling survival rate and a large sapling bank that forms a reliable source of tree recruitment. The life-history stage characteristics of A. polyacantha suggest that this is an early successional species.

We conducted a study on how Acacia sieberiana respond to repeated burning in the Kidepo National Park in northeastern Uganda. The study was conducted to understand effects of common burning regimes (early dry season, late dry season, and no burn [control]) in the area on Acacia sieberiana. The three treatments were applied for three consecutive years to 14 replicate blocks in a randomized block design. All A. sieberiana trees were number tagged and monitored for height and girth (diameter at breast height) growth. All fires were set as head-fires and attained intensity ranging between 422 and 5693 kW · m −1 . Both early and late dry season burning increased the number of small ( A. sieberiana trees after 2 yr. Burning did not affect the growth rates. Although the number of trees 250 cm in the third year. Mortality attributed to elephant browsing was important in all treatments but a substantial portion of mortality could not be attributed to any particular cause. In the late burn, fire was the most important mortality factor. Thus, 2 yr of burning may be used as a tool to stimulate recruitment of A. sieberiana , but additional years of late dry season burning will increase the mortality of older trees.

Dry and mature tree fruits are a potential source of protein for goats in the semi-arid areas of southern Africa, but their chemical composition and feeding value is largely unknown. This study presents the chemical composition and in vitro fermentation of indehiscent whole fruits and separated seed and hull fractions from Acacia nilotica, Acacia erubescens, Acacia sieberiana, Acacia erioloba, Piliostigma thonningii and Dichrostachys cinerea trees. Results indicate that the N contents of whole fruits ranged between 13.5 g/kg DM (A. nilotica) and 27.1 g/kg DM (A. erubescens). Seeds had a higher N content than hulls for all tree species. A. nilotica, D. cinerea and P. thonningii fruits had high levels of extractable phenolics (758, 458 and 299 g/kg DM, respectively). Soluble phenolics (SPh) and ytterbium precipitable phenolics (YbPh) levels were negatively correlated to in vitro gas production but positively correlated to in vitro organic matter degradability (iOMD). Partition factors for whole fruits at 48 h ranged between 3.6 mg/ml for A. erioloba and 7.8 mg/ml for A. nilotica. Seeds of A. erioloba, A. erubescens and P. thonningii were consistently fermented more efficiently throughout the incubation period compared to their whole fruits or hulls. Estimating in vitro degradability of phenolic-rich substrates through filtration procedures can give erroneous results due to the loss of soluble phenolics, which are not necessarily degradable. The feeding value of fruits from D. cinerea and A. nilotica tree species may be reduced due to the presence of high levels of phenolics.

The study aimed at determining the population status of the different Acacia tree species producing gum arabic in the undisturbed, grazed and cultivated habitats in the Karamoja region, Uganda. A total of 135 sample plots each measuring 20 × 20 m2 (0.04 ha) with each habitat having 45 plots were selected and established in the seven counties using a simple random sampling technique. The tree species present, their abundances and sizes were recorded. Twelve Acacia species were identified and a total of 5535 recorded in the sampled area. Out of these, five were gum-producing acacias. Acacia senegal dominated the acacias in all the seven counties and in all habitats of Karamoja with Acacia nilotica (72.3%), Acacia seyal (13.4%), Acacia sieberiana (4%) and Acacia gerrardii (2.6%). Non-gum-producing acacias constituted 7.19% of the total abundance. The tree densities increased with increase in tree size in the undisturbed and grazed habitats but decreased in the cultivated habitat. Most Acacia trees were of large size, an indication of old age and poor regeneration that could affect their future population status. It is recommended that further investigations be carried out into the causes of poor regeneration of Acacia species.

Cyanogenic glycosides are anti-nutritional components capable of liberating hydrogen cyanide, a respiratory poison that has been reported to be responsible for the death of livestock that browse some Acacia species containing these compounds. The objective of the study was to improve the nutritive value of the pods of Acacia sieberiana by reducing their contents of cyanogenic glycosides through ensiling, and to examine the influence of various levels of added molasses and urea on the aerobic stability of the silage. In experiment 1, laboratory silages, prepared by mixing ground pods with water in two ratios (60:40 and 40:60 w/w pod material:water), were put into 250 ml polythene bottles, ensiled for 4, 7, 14, 21, 28 or 35 days and analyzed for cyanide. In experiment 2, silages prepared as described above but using only one of the ratios (40:60), and with the addition of molasses (0, 30 or 60 g kg−1) and urea (0, 2.5 or 50 g kg−1) were included in a 3 × 3 factorial design, to study the effects of these additives on the stability of the silage. The period of ensilage was 14 days. In experiment 3, the concentrations of molasses and urea were modified to 0, 45 or 90 g kg−1 and 0, 7.5 or 15 g kg−1, respectively, and the period of ensilage was extended to 45 days. The parent material contained 130.6 mg CN kg−1 DM and ensiling the material for 35 days reduced the concentration to 18.1 mg CN kg−1 DM. Moisture content at ensiling significantly (P < 0.001) affected the concentration of cyanide in the stored silages. Silages opened after 14 days were unstable irrespective of the use of additives. However those with combined urea and molasses exhibited a slow rate of deterioration and low fungal counts. Extending the period of ensiling to 45 days improved the aerobic stability of all the silages. The addition of urea significantly (P < 0.001) increased the pH, crude protein content, gross energy and fermentation acids while molasses treatment increased (P < 0.001) the lactic acid and ash content of the silages. Ensiling ground pods for 45 days was enough to reduce the cyanide content to non-toxic levels and produced a silage which was aerobically stable, while the inclusion of additives further improved the quality of the silages. Copyright © 2004 Society of Chemical Industry

Thin Layer Chromatography (TLC) was investigated as a potential tool with which medicinal bark products used in South African traditional healthcare may be authenticated. Dried bark products are difficult to identify, and misidentification or adulteration increasingly affect their appropriate use and accurate documentation of their trade. A traditional medical practitioner pinpointed eight bark species used in KwaZulu-Natal, South Africa, that are difficult to identify. These were Ekebergia capensis (Meliaceae), Harpephyllum caffrum (Anacardiaceae), Rapanea melanophloeos (Myrsinaceae), Schotia brachypetala (Caesalpiniaceae), Croton sylvaticus (Euphorbiaceae), Albizia adianthifolia, Acacia sieberiana and Acacia xanthophloea (Mimosaceae). Three reference bark samples of each species were extracted in ethanol or hexane, separated on silica gel in petroleum spirit : ethyl acetate : chloroform : formic acid (8:7:5:1), and treated with anisaldehyde or vanillin reagents. TLC proved useful for showing similarities in the phytochemical fingerprints of a single species, but less so in distinguishing between the phytochemical fingerprints of different species. The technique assisted in confirming the identity of several medicinal bark products.

In the first of a two-phased study, changes in rumen pH and concentrations of VFA were evaluated on diets based on pasture straw (negative control) or straw supplemented with alfalfa (Alfalfa diet), pods of Acacia sieberiana (Sieberiana diet), Acacia nilotica (Nilotica diet) or Leucaena leucocephala (Leucaena diet) for South African Merino rams. In the second phase, the effects of the same diets on the degradation of extracted straw in nylon bags and activities of microbial enzymes were investigated. The pH and total concentration of VFAs in rumen fluid ranged from 6.2 to 6.5 and 30–53 mmol l −1 , while degradation of DM and NDF varied from 126 to 269 g kg −1 DM and 233–309 g kg −1 NDF, respectively, among diets. Variations in pH were not significant ( P >0.05), but diet influenced ( P

Two experiments were designed to investigate the effect of legume tree-pods and ensiling on the intake and relative palatability of six feeds by goats and sheep. In the first experiment, the feeds offered were pasture hay (Themeda triandra), alfalfa (Medicago sativa), pods of Acacia sieberiana, Acacia nilotica and Leucaena leucocephala. In the second, silage from the pods of A. sieberiana was included as the sixth feed in order to examine the effect of ensiling on intake and palatability since this process was devised as a means of detoxifying cyanogenic glocosides known to be present in the leaves and pods of this species. Intake (Ti) and relative palatability (Pi) were determined using 3 goats and 3 sheep in each experiment. Since the feeds had different dry matter contents, intake was expressed as a ratio of the quantity offered (Ti/Ai). Using the hay offered (A1) and intake (T1), as standard, relative palatability indices were calculated as Pi = (Ti/Ai)/(T1/A1) where i represented the other feeds. In experiment 1, goats consumed more hay than alfalfa or pods. Sheep consumed more leucaena than all the other feeds. In experiment 2, the intake of all feeds except nilotica increased over time. Hay and leucaena had the highest Pi for goats and sheep, respectively, in experiment 1. In experiment 2, silage from pods of A. sieberiana had the highest Pi while the ranking for goats remained unchanged. The nilotica meal had the lowest Pi in both experiments. Pi was affected (p > 0.0001) only by feed type in experiment 1 but in experiment 2, feed type, animal species and weight significantly (p > 0.01) affected Pi. The results show that the pods of L. leucocephala and A. nilotica were the most and least preferred by goats and sheep, respectively, and that ensiling significantly improved the intake and palatability of the pods of A. sieberiana. However, some feeds that are least preferred in times of abundance and variety could be relished during periods of scarcity and severe feed shortages, based on animal survival instinct.

The study evaluated the synergism between wheat bran and tanniferous feeds (dry meal or silage from pods of Acacia sieberiana ) on intake and digestibility of various nutrients as well as weight gain in sheep fed a basal diet of veld hay ( Cynodon dactylon ). Dietary treatments comprised veld hay given ad libitum and supplemented with: 270 g of wheat bran (WB) alone (T 1 ), 203 g of WB plus 83 g of silage (T 2 ), 135 g of WB plus 165 g of silage (T 3 ), 330 g silage without WB (T 4 ) or 306 g of dry pods without WB (T 5 ). The silage was prepared by mixing ground pods with water in a ratio of 40:60 (weight of pod:weight of water) and ensiling in 200-l drums for 35–45 days. Thirty young South African Merino sheep (15 males and 15 females), averaging 24 kg liveweight and 8 months of age, were blocked by sex and weight and within block, randomly distributed to the dietary treatments. A growth study was followed by a metabolism phase. All animals were slaughtered at the end of the trial to evaluate the weight of the dressed carcasses and some body organs. Faecal samples were examined at the beginning and at the end of the trial in order to evaluate the effect of tannins on endoparasites. Dry matter intakes for treatments 1, 2, 3, 4 and 5 were 1017, 1087, 1169, 1238 and 1214 g, respectively. Average liveweight gains (ADG) were 97, 114,114, 132 and 123 g in the same order. The addition of silage increased ( P P >0.05) on liveweight gain and feed conversion efficiency. Increasing the levels of silage in the diet linearly ( P P >0.05) among treatments but the WB diet promoted higher N digestibility. The pod and silage diets increased ( P P P >0.05) among treatments and the organs had no lesions. The results show that combining WB and silage did not show significant synergism but condensed tannins present in the silage and pod supplements produced beneficial effects probably by forming tannin–protein complexes which by-passed the rumen and were digested at the lower segments of the gastro-intestinal tract. The results of the study have shown that the pods of Acacia sieberiana can constitute an important source of nitrogen to livestock and the liveweight gains are indications that, if legume pods are well managed, they can reduce weight loss in animals grazing low quality rangelands and enhance production.

This study evaluated the effects of feeding alfalfa and pods of tree legumes on rumen pH and ammonia concentration as well as in sacco degradability of dry matter and fibre constituents of maize stover, alfalfa hay and their neutral detergent extracts. The feeds were incubated in the rumens of five South African Merino sheep fed individually in an incomplete (5 × 4) Latin square design using five diets. The diets comprised equal proportions of pasture hay and either alfalfa (Alfalfa diet) or pods of Acacia sieberiana (Sieberiana diet), Acacia nilotica (Nilotica diet) or Leucaena leucocephala (Leucaena diet). The fifth diet was composed of pasture hay alone (Hay diet) and served as a negative control. Supplementation of hay with either legume pods or alfalfa significantly (p 0.05) the degradability constants lag time (LT), slowly degradable fraction (B), potential degradability (PD), effective degradability (ED) and rate of degradation (C) of dry matter (DM) but significantly (p

The host specificity, infection process and effectiveness of nodules produced by several African sinorhizobial strains on different Acacia and Prosopis species (Leguminosae, Mimosoideae) were studied. Sinorhizobium arboris strain HAMBI 1552T, S. kostiense strains HAMBI 1489T and HAMBI 1493, S. saheli strain HAMBI 1496 and S. terangae bv. acaciae strain ORS 1058 induced nitrogen fixing nodules on seedlings of the following African or Latin American species (marked with *): A. angustissima * , A. mellifera, A. nilotica, A. oerfota (synonym A. nubica), A. senegal, A. seyal, A. sieberiana, A. tortilis subsp. raddiana, P. chilensis * , P. cineraria, P. juliflora and P. pallida * . All strains increased plant yield significantly compared with uninoculated seedlings watered with nitrogen-free medium, but none appeared to be superior. The sinorhizobial strains were unable to effectively nodulate Sesbania rostrata (Papilionoideae). All roots had hairs, but particularly in the case of Acacia spp. they were often sparse. After inoculation root hairs were deformed and, in general, infection in Acacia spp. occurred through short root hairs and in Prosopis spp. through longer ones. After entry, the rhizobia filled infection pockets in the root hair, which later expanded into sac-like structures. When infection threads occurred, they usually started from sac-like structures. Elongation and ramification of the nodules indicated that Acacia spp. and Prosopis spp. have indeterminate nodules. A persistent apical meristem, which is the characteristic feature of the indeterminate nodule type, was much clearer in Prosopis spp. than in Acacia spp. Sinorhizobial strains formed tumour-like structures with undifferentiated cell tissue on the Australian acacia A. holosericea and ineffective, nodule-like structures on the African P. africana.

This study determined nitrogen degradability and digestibility of rumen undegradable nitrogen using mobile nylon bag (MNB) and pepsin/ pancreatin in vitro technique (IV) of 40 browse species. Thirty Ethiopian highland sheep fitted with rumen cannulae were used in nitrogen (N) degradability studies. Six steers fitted with rumen cannulae were used in preparation of 16-h and 24-h ruminal undegraded residues and four steers fitted with distal abomasal cannulae were used in MNB technique. The browses varied widely in nitrogen solubility (15-468 g kg -1 ), potential degradability (223-976 g kg -1 ), rate of degradation (0.13-24% h -1 ) and effective degradability (135-821 g kg -1 ). The apparent N digestibility (ND) of the rumen undegraded residues differed significantly (P 0.05) was observed in ND of 16-h and 24-h residues. The ND of the 16-h residue varied from -218 to 759 g kg -1 and 169 to 851 g kg -1 for MNB and IV methods, respectively. Browse species with high tannin contents such as Acacia hockii, A horrida, A melanoxylon, A persiciflora, A salicina, A saligna and Flemingia macrophylla had high rumen by-pass and a low ND, while Sesbania spp and A nilotica with low tannin contents underwent rapid and extensive dry matter and nitrogen degradation in the rumen. Acacia sieberiana, Chamaecytisus palmensis, Erythrina spp, Gliricidia sepium, Samanea saman and Enterolobium cyclocarpum had high proportions of protein escaping rumen degradation (BP) and with a high proportion of the by-pass protein digested in the intestine, therefore these browses had a high potential as protein supplements. The ND measured with the MNB were significantly lower (P < 0.001) than by the IV method. The correlation between MNB and IV was high and significant (R 2 = 0.89, P < 0.0001) as also indicated by the regression equation (SE in parentheses): MNB = -22.8 (4.55) +1.0 (0.08)IV (RSD = 10.56, R 2 = 0.79, n = 40, P < 0.001). The intercept of the linear relationship obtained was different from zero while the slope was not different from unity. Multiple regression analysis suggested that some of the unexplained variation could be accounted for by either nitrogen, acid detergent fibre, total phenolics or neutral detergent fibre bound tannin levels in browses. The IV method is accurate for estimating digestibility of ruminally undegradable N, and hence its use would considerably reduce the need for delicate surgery and the elaborate procedures involving the MNB technique.

International audience; Woody plant encroachment in grasslands is a worldwide phenomenon. Despite many studies, the consequences of woody plant encroachment on sub-canopy vegetation and soil properties are still unclear. To better understand the impacts of trees on grassland properties we examined the following questions using a mountainous sub-tropical grassland of South Africa encroached by an indigenous tree, Acacia sieberiana as a case study: (1) Do trees increase sub-canopy herbaceous diversity, quality and biomass and soil nitrogen content? (2) Do large trees have a stronger effect than medium-sized trees on grass and soil properties? (3) Does the impact of trees change with the presence of livestock and position of trees in a catena? We studied grass and non-graminoid species diversity and biomass, grass quality and soil properties during the wet season of 2009. Nitrogen in grass leaves, soil cation exchange capacity and calcium and magnesium ion concentrations in the soil increased under tall Acacia versus open areas. Medium-sized Acacia decreased the gross energy content, digestibility and neutral detergent fibre of grasses but increased the species richness of non-graminoids. Tall and medium Acacia trees were associated with the presence of Senecio inaequidens, an indigenous species that is toxic to horses and cattle. The presence of livestock resulted in a decrease in herbaceous root biomass and an increase in soil carbon and leaf biomass of grass under Acacia. Tree position in the catena did not modify the impact of trees on the herbaceous layer and soil properties. For management of livestock we recommend retaining tall Acacia trees and partially removing medium-sized Acacia trees because the latter had negative effects on grass quality.

Effects ofA. sieberianatrees on soil properties and plant diversity were investigated in Songa pastures, Rwanda. Tree characteristics and crown architecture ofA. sieberianawere studied. Soil properties were assessed and plants were identified under and away from tree crowns. Counts of individual plants/species were done only under tree crowns. Nitrogen, P, and K were analysed in the soil, grass, andA. sieberianaleaves. Plant diversity was determined using Simpson's diversity index. Data were subjected to ANOVA. Soil organic carbon (SOC), cation exchange capacity (CEC), Ca2+, N and pH, and plant diversity were higher in soils under tree canopies than in open areas. Tree leaves were significantly richer in N and poorer in P and K as compared to grasses. Tree crowns grew wider and horizontal and developed intertwined secondary branching, reducing light intensity to as low as 38% under tree canopies compared to the open pasture. At 3 trees/ha stocking,A. sieberianatrees shaded 0.18 ha and herbaceous plants and grasses unpalatable to livestock dominated under tree canopies. A tradeoff ofA. sieberianatree value versus the loss of palatable grass due to tree presence needs to be assessed to decide whether the trees should be included in pastures and if yes, the apporpriate stocking identified.

The effects of heat treatment and fire on seed germination of Acacia sieberiana D.C. and Acacia gerrardii Benth. were studied. Dry heat and fire were studied separately. Seeds treated with dry heat were set to germinate in petri-dishes under laboratory conditions. Other seeds were planted in plots at the Uganda Institute of Ecology, Mweya, which were then burnt, and subsequent seedling emergence was monitored. The effect of heat treatment on seed germination depended on heat intensity and duration of exposure. Higher intensities reduced the germination capacity of Acacia seeds. Short exposure of seeds stimulated germination but prolonged exposure rapidly reduced seed viability. A. sieberiana had a higher heat resistance than A. gerrardii. The survival and germination of seeds after fire increased with depth of burial and A. sieberiana survived better than A. gerrardii. The germinability of seeds of A. gerrardii was not significantly increased by fire.

This study evaluated differences in gas production of leaves gathered from a range of multi-purpose trees (MPT) of Acacia, Cajanus, Chamaecytisus, Leucaena, Ricinus, Sesbania and Veronia species and the effect of their digesta (obtained by fermenting MPTs for 24 h) on gas production of Napier grass (Pennisetum purpureum. Schumach) (Napier GP ) and neutral-detergent fibre (NDF) extracted from Napier grass (NDF GP ). Fresh samples of MPTs were incubated in triplicate or quintuplicate in a medium prepared from sieved rumen liquor harvested from two rumen-fistulated cows fed native pasture hay ad libitum and 2.0 kg cottonseed cake per head day -1 . There was a wide variation in the volume of gas produced by the MPTs. With the exception of the leaves of R. communis (castor oil plant) and L. pallida (14189), the MPTs produced less (P < 0.05) gas than Napier grass. Sesbania goetzei (1279 and 15007), and C. cajan (12842) produced gas at a slower (P < 0.05) rate than Napier grass. The digesta of MPTs induced rates of Napier GP that ranged from 0.63 to 0.83 the value obtained with the Napier grass digesta. With the exception of S. sesban (10865), C. palmensis and R. communis leaves, the MPT digesta induced Napier GP similar to or slightly higher than the Napier grass digesta. The digesta of S. sesban (10805), A. siberiana (pods), C. cajan (11443, 12842) and C. palmensis depressed the cumulative extent of NDF GP relative to Napier grass digesta. The MPT digesta prolonged the lag phase that precedes NDF GP . The results are discussed in relation to the effect of MPT digesta on aspects of cell wall fermentation and are corroborated with results obtained in vivo. It was concluded that the major effect of antifermentation factors in the MPTs would be manifested in vitro in prolonged lag phase preceding the onset of NDF GP and in slowed rate of Napier GP .