Milicia Excelsa Research Articles

Iroko wood (Milicia excelsa C.C. berg), a good candidate for high-speed rotation-induced wood dowel welding: An assessment of its welding potential and the water resistance of its welded joints

The objective of this study was to determine the explanatory factors for the cold water resistance of welded joints of Iroko wood (Milicia excelsa C. C. Berg). The welding parameters considered and measured were grain direction, welding time, pre-drilled-hole depth, and rotation speed on welding temperature. The pull-out resistance of joints immersed in distilled water from 10 °C to 20 °C for five periods (7, 14, 21, 28, and 35 days) was also tested. The results show that the maximum welding temperatures (125 °C and 231 °C) were reached in less than 5s for all the dowelled specimens and obtained with the specimens inserted in the tangential direction, at 2100 rpm and 25 mm hole depth. The maximum value of the pull-out strength (3.28 MPa) was obtained with specimens inserted in the radial direction, at 1050 rpm and 20 mm hole depth. However, no significant difference was found between this result and those obtained with specimens inserted in the tangential direction, at 2100 rpm and 25 mm hole depth and bonded with PVAc. Despite the drastic decrease in pull-out strength of the specimens immersed in cold water within each group compared to the G1 reference group, some welded joints showed good maximum pull-out strength, greater than 2 MPa, and no failure after 5 weeks in cold water. MALDI-TOF analysis reveals the presence of inhibitory oligomers of the stilbene class at (379 Da = no Na+, and at 402 Da with Na+) chlorophorin (C24H28O4), and geranyl-trihydroxy-stilbene (364 Da) which remain insensitive to water. In addition, the presence and slow leaching at (381 Da no Na+) of geranyl tetrahydroxy-stilbene, at 380 Da of cudraxanthone I (C23H24O6), and at (377 Da) of neocyclomorusin (C25H24O7) is an additional reason to justify the water stability of the Iroko welded joints. In conclusion, Iroko wood is a good candidate for the wood welding technique.

Simulation of A Solar Drier for Iroko Wood (Chlorophora Excelsa) in A Tropical Environment

In a previous study conducted by Simo Tagne to designing a solar dryer based on mathematical equations for iroko wood in Cameroon, Africa. However, there is no complete simulation of the drying process on the tool, resulting in the lack of detailed elaboration of the iroko wood drying process. The purpose of this study is to simulate in detail the drying process on the tool using an ANSYS simulation. The model used in this simulation still uses the same mathematical model that has been studied before. This research begins by setting up the ANSYS application with the previous mathematical model, environmental conditions, and tool specifications. Furthermore, simulations are carried out using the ANSYS application with measurements of pressure, temperature, velocity and mass transfer. From this simulation obtained results for the distribution of pressure, temperature, velocity, and mass transfer. From all these distributions, it is sufficient to describe the drying process of the tool according to the mathematical model that has been studied previously.

Possibilities of Using Essences Alstonia Congensis Engler, Cynometra Hankei Harms, Cynometra Sessiliflora Harms (De Wild) Lebrun and Milicia Excelsa (Welw.) CC Berg Based on the Analysis of Vulnerability: Case of the Biaro Forest (Ubundu, DR Congo)

A study was carried out in the Biaro forest to determine the vulnerability index of the species Alstonia congenis, Cynometra hankei, Cynometra sessiliflora and Milicia excelsa. Over an area of 50 hectares; 526 trunks of Alstonia congensis, 87 trunks of Cynometra hankei, 482 trunks of Cynometra sessiliflora and 482 trunks of Milicia excelsa were identified by the method of mesuring the diameters of these trees. At the end of the results, all these four species are declared vulnerable in this Biaro forest.

An experimental and theoretical analysis of the dynamic response of solar drying in natural convection under rainy month of Maroua (Cameroon) of three tropical wood species

ABSTRACT This work aims to study and characterize the drying kinetics, the heat mass transfer coefficients, the densities, the thermal effusivities, the thermal diffusivities and Young’s modulus of three tropical kinds of wood: ayous (triplochiton scleroxylon), sapelli (Entandrophragma cylindricum) and iroko (Milicia excelsa). A comparison has been doing between drying using a low expensive solar dryer in natural convection and drying using open-air conditions. The novelty of this work is to use an experimental study during the rainiest period in the city of Maroua, one city in Cameroon with a hard climate. Densities are influenced by the origin of the samples in the plank and increase linearly with the moisture content. At 30&per; of humidity (d.b), average densities of sapelli, iroko, and ayous were equal to 1000, 760 and 600 kg/m3 respectively. Thermal effusivities and thermal diffusivities increase linearly with the moisture content. Thermal diffusivities of the three kinds of wood are very near (2 × 10−7 m2/s at 30&per; of humidity (d.b)) and thermal effusivities increase with the wood densities with values located from 560 to 620 J/(K.m2.s0.5) at 30&per; of humidity (d.b). The heat mass transfer coefficients are influenced by the night and day and vary from 1.5 × 10−8–1.8 × 10−7 m/s for the global mass transfer coefficients, and from 1.8–6.5 W/(m2K) for the heat transfer coefficients. According to the variations of the values of young’s modulus and the drying kinetics, drying in open-air conditions is more rapid and not recommended than one in the solar dryer. The equilibrium humidity of all samples is near 10&per; (d.b).

Impact of thermal modification on color and chemical changes of African padauk, merbau, mahogany, and iroko wood species

Abstract Thermal modification is an environment-friendly technology for improving various wood properties, especially the dimensional stability, decay resistance, and color homogeneity. In this work, four tropical wood species (African padauk, merbau, mahogany, and iroko) were thermally modified by the ThermoWood process. The influence of heat treatment on the color and chemical changes of wood was studied by spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, and wet chemistry methods. As the temperature increased, a decrease in lightness (L*) and a simultaneous decrease in chromatic values (a*, b*) were observed, indicating darkening and browning of the wood surface. As a result of the heat treatment, the relative content of hemicelluloses decreased the most in merbau and mahogany, while the thermal stability of iroko and African padauk was higher. All examined wood species showed a strong correlation between the lightness difference value (ΔL*) and the content of hemicelluloses (r = 0.88–0.96). The FTIR spectroscopy showed that the breakdown of C═O and C═C bonds in hemicelluloses and lignin plays an important role in the formation of chromophoric structures responsible for the color changes in the wood.

Physical and Combustion properties investigation of hybrid briquettes from tropical Sawdust: Case study of Iroko (Milicia excelsa) and Padouk (Pterocarpus soyauxii)

In the wood processing industry, sawmills generate huge amounts of sawdust as a renewable energy source. This paper aims to describe the production process and investigate the physico-chemical properties of mixed briquettes from two tropical sawdust species, including Iroko (Chlorophora excelsa) and Padouk (Pterocarpus soyauxii) and starch binder. The sawdust from each wood was dried, mixed in the ratios of 100:0; 75:25; 50:50; 25:75; 0:100 and then carbonised in the pyrolyser. The biochar was ground, mixed in the combinations of 75:25; 50:50; 25:75 and compacted using a manual hydraulic press. Proximal and ultimate analyses were applied to determine the combustion characteristics of the briquettes produced according to ASTM standards and Van Kreleven models. The results of briquette production showed that pure Padouk sawdust (P) has a high yield (18.4%), while mixed sawdust (C’) has a lower yield (12.4%). The density varies from 0.28 g/cm 3 to 0.53 g/cm 3 and the ash content from 3.48% to 7.46%. The gross calorific value of the briquettes produced varies from 22.623 MJ/kg to 24.719 MJ/kg. The highest Gross Calorific Values (GCV) obtained on Padouk briquettes indicates their high content of extractables. Ultimate analysis of the samples showed that the briquettes were highly carbonaceous. The Van Krevelen diagram shows an atomic H/C ratio of less than 1.5 and an O/C ratio of less than 0.8 which indicate that the briquettes are highly flammable. The briquettes produced are suitable as an environmentally friendly alternative energy source as they have low moisture and ash content (below 10%), and high calorific values.

SPATIALLY EXPLICIT ASSESSMENT OF THE SUITABLE AREAS FOR THE THREATENED IROKOS (MILICIA EXCELSA [WELW.] C.C. BERG) CONSERVATION IN BENIN: A COMBINATION OF GEOSTATISTICS AND ECOLOGICAL NICHE MODELING

Although Iroko (Milicia excelsa) is listed endangered and has a great socioeconomic and cultural importance in Benin, there have been few attempts to definition of sustainable conservation strategies for the species. This study explored the spatial patterns of the species and tested if the species distribution may be affected under future climates forecasts. Moran index was used to measure the spatial autocorrelation of the abundance of Iroko. For the niche modeling, records of the species were added to bioclimatic variables (current and future conditions) and soil layers in the maximum entropy algorithm. Results showed overall a spatial dependency between Iroko population according to the density (P < 0.001). The population density seems similar between 0 and 3 km but differ from 3 to 150 km. A slight increase was noted from the present-day distribution to the future forecasts (4.71 % and 6.95 % respectively following the scenarios RCP4.5 and RCP8.5). Urgent conservation actions are needed to safeguard the remnant populations of Iroko in Benin.

An Investigation into the Strength Properties of Three Reclaimed Structural Timber Joist Within the University of Ibadan Community

Background and Objective: The investigation presents the results of selected test assessment on physico-mechanical properties of three selected wood residues within the University of Ibadan Campus, Oyo State, Nigeria. Often, reclaimed planks were considered as useful material for heating and energy production, hence, potential re-usability of these residues for plate rack production were determined. Materials and Methods: Four planks of the selected three wood samples each were collected from the University of Ibadan community. The 12 pieces wood samples were cleaned, plained, and converted into required dimension; samples were dried to about 12%moisture content before tests. Selected physico-mechanical properties test (moisture content, volumetric shrinkage, modulus of elasticity, and modulus of rupture were carried out according to ASTM standards. The data obtained were subjected to analysis of variance (ANOVA). Results: The results of mean density show that <i>Gliricidia sepium, Milicia excelsa </i>and <i>Funtumia elastica </i>had 1032±0.97kg/m³, 548±0.57kg/m³ and 613±0.33kg/m³, respectively. The mean value for moisture content of <i>G. sepium, M. excelsa and F. elastica</i> ranges from 12.47±1.21, 20.84±1.21 and 18.13±1.21, respectively. While, volumetric shrinkage of <i>G. sepium, M. excelsa and F. elastica </i>ranged from 20.55±2.79, 7.48±2.79 and 11.43±2.79. The <i>G. sepium, M. excelsa and F. elastica </i>had MOE values of 8793.13±643.43 N/mm², 8083.64±643.43 N/mm² and 4299.54±643.43N/mm². The mean values for MOR of <i>G. sepium, M. excelsa and F. elastica </i>ranges 404.69±12.362 N/mm², 434.27±12.36N/mm² and 388.34±12.36N/mm². Conclusion: <i>Gliricidia sepium </i>wood had the highest mean density, low shrinkage value and modulus of elasticity. Therefore, it was found most suitable wood slab for plate rack production from reclaimed wood joist.

Milicia excelsa (Moraceae) reversed the effects of letrozole-induced aromatase inhibition in rats with polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is an endocrinopathy affecting 5-20% of women of childbearing age.There is no single drug for the treatment of PCOS and current therapies have significant side effects. This study evaluated the ability of Milica excelsa to improve PCOS symptoms in rats. Induction of PCOS was achieved using letrozole (areversible aromatase inhibitor; 1mg/kg; given orally for21days). From day 22, PCOS rats received the aqueous extract of M.excelsa roots (14 and 140mg/kg). Clomiphene citrate (1mg/kg) was administered to the positive control. The negative and the normal controls received the vehicle (5%DMSO). Treatments were given orally for 7 or 14days. Vaginal smears were scrutinized daily during the experiment. Body weight was measured hebdomadal. Animals were sacrificed after the two treatment periods for biochemical and histological analyses. Aromatase inhibition caused hyperandrogenism (p<0.001), overweight (p<0.001) and fat accumulation (p<0.001). It also blocked the estrous cycle at the diestrus phase and altered ovarian dynamics as evidenced by the accumulation of cystic (p<0.001) and atretic (p<0.001) follicles. In contrast, M.excelsa induced weight loss (p<0.001), reduction in fat weight (p<0001), and lower serum androgen and LH levels (p<0.001). It also restored the estrous cycle andimproved ovarian dynamics by increasing the amount of Graafian follicles (p<0.001) and corpora lutea (p<0.001), and decreasing that of cystic and atretic follicles (p<0.001). Milica excelsa corrected hyperandrogenism and overweight in PCOS animals, and reduced cyst formation and follicle atresia in their ovaries.

CHARACTERIZATION OF THE NATURAL FLORA OF THE UNDERSTORY OF THE RUBBER PLANTATIONS IN SOUTHERN COTE D’IVOIRE: CASE OF THE RUBBER PLANTATIONS OF THE CNRA ANGUEDEDOU

Objective: The study was conducted in the rubber plantations of the National Agricultural Research Centre (CNRA) of Anguédédou in the south of Côte d'Ivoire, to characterize the natural biodiversity of the undergrowth of rubber plantations, through the floristic composition and the evolution of the number of species according to the age of the plantations. Methodology and results: The methodology focused on the surface inventory. Thus, 36 surveys of 20 m x 10 m, or 200 m², were installed and inventoried through the rubber plantations of different age classes ([1 to 5 years], [6 to 10 years], [11 to 20 years] and [21 to 40 years]), abandoned rubber plantations and secondary forest. Regeneration was evaluated in plots with a 5 m (25 m²) coastline. The results have shown that rubber plantations are rich in 130 natural plant species. With the exception of rubber plantations from 1 to 5 years and especially of abandoned rubber plantations, the influence of this crop on the natural flora is felt in plantations from 6 to 10 years, with only 34 species. However, this flora evolves with the aging of the plantations. In abandoned plantations, 75 species were inventoried with a good presence of endemic species such as Chlamydocarya macrocarpa, Angylocalyx oligophyllus, Chassalia kolly, Mussaenda tristigmatica. There are also some rare and/or endangered species such as Albizia adianthifolia, Baphia nitida, Commelina benghalensis, Culcasia scandens, Gloriosa superba, Greenwayodendron suaveolens, Millettia zechiana and Milicia excelsa. The floristic similarity between abandoned rubber plantations and secondary forest, indicates a shift from abandoned rubber plantations to forest formations with high regeneration density, mainly in abandoned plantations. Conclusion and application: The study showed that the impact of rubber culture is felt on the natural flora of young rubber plantations. However, when plantations are abandoned, the environment becomes secondary forest. This investigation deserves to be carried out in other rubber plantations of other ecological zones of Côte d'Ivoire.

Correlation between dry density and shrinkage in eight tropical hardwood species

Eight tropical hardwood species were assessed for their density and radial, tangential and volumetric shrinkage, after which the relation between the density and different shrinkages was checked through correlation and regression. The results showed that the highest mean density was observed in Milicia excelsa with 900.63±50.13 kg/m³, followed by Afzelia africana, Nesogordonia kabingaensis and Nauclea diderichii with 831.25±41.67 kg/m³, 808.75±20.88 kg/m³ and 801.88±46.40 kg/m³, respectively. The mean density for Cassia simea was 781.88±27.71 kg/m³, Mansonia altissima 593.13±65.98 kg/m³, and Sterculia tragacantha 481.25±111.73 kg/m³, while the least density was observed in Treculia africana with 463.75±67.88 kg/m³. The highest volumetric shrinkage was observed in Nesogordonia kabingaensis with 14.71±2.28%, and the least in Cassia simea with 5.11±2.65%. It is concluded that there exists positive but weak correlation between density and the shrinkages in the eight tropical hardwood species.

Diversity and conservation prioritisation of plant species utilised by communities living in the forest areas managed by the Benin National Timber Office

The diversity of forest resources is threatened in its current form of exploitation by rural communities. In order to contribute to the sustainable use of forest resources, this study aimed to assess the diversity of ‘utilitarian’ plant species (those that are useful to humans) among communities living in the 11 classified forests managed by the National Timber Office of Benin (Office National du Bois du Bénin, ONAB) and to identify priority species for conservation. Semi-structured interviews were conducted with 385 riparian residents of the forests using a simple random sampling method. The data collected focused mainly on plant biodiversity. The ecological parameters of habitats, such as the number of genera and species according to families, were calculated. In addition, the prioritisation method used four approaches and eight criteria that made it possible to identify priority species for conservation. Overall, the study revealed the existence of 97 utilitarian species divided into 33 families and 76 genera in the forest areas. The ten priority species for conservation, in order of priority as per the point score procedure, are: Khaya senegalensis, Afzelia africana, Khaya grandifoliola, Pterocarpus erinaceus, Anogeissus leiocarpa, Milicia excelsa, Albizia zygia, Vitex doniana, Antidesma laciniatum and Bombax costatum. This study provides scientific support for conservation planning and as a decision-making tool for the socio-economic conservation of these species.

Assessment of choice of wood species for construction purpose by smallholder furniture makers and carpenters in Ibadan Metropolis, Oyo State

This study assessed the preference of wood species used for furniture making and roofing in Ibadan metropolis, Nigeria. A cross-sectional assessment study, which employed questionnaire and on-site observations, was used. A sample of 100 respondents was ramdomly selected from wood users comprising mixtures of active furniture makers and carpenters in five local government areas out of the 11 local government areas of Ibadan metropolis. Data were analyzed using descriptive statistics and correlation to establish relationship between education, year of experience and choice of wood species. From the study, 18 and 17 species were found to be available for the production of furniture and roofing respectively in the study area. Gmelina arborea (41%,) follow by Khaya senegalensis (14%), Mansonia altissima (13%), Milicia excelsa (11%), Cordia millenii (11%) and Celtis zenkeri (10%) are the prominent and the most prefer wood species for furniture making. While Anogeissus leiocarpus (52%) follow by Milicia excelsa (20%) and Cola acuminate (15%) and Spent Elaeis guineensis wood (9%) were the most prominent prefer wood species for roofing.100% of the respondent are into furniture making while 96% of the respondent are into furniture making and carpenters. The preference criteria of species for furniture and roof making are strength (29%), good finished(24%), visual appearance(17%), durability(10%), easy machining(12%), availability(2%) and the knowledge of the wood species(6%). concerted effort through reforestation and afforestation for continuous supply of the preferred wood species to forest industries need to be carried out.

The influence of planting orientation and ecotype on sprouting and survival of stem cuttings of African teak (Milicia excelsa (Welw.) in Kenya

African teak (Milicia excelsa (Welw.) is a giant deciduous forest tree which belongs to the Moraceae family and is now threatened by extinction due to over exploitation. This study determines the influence of planting orientation and ecotype on sprouting and survival of cuttings of African teak. The cuttings were collected from the Coastal and Western regions of Kenya. A Randomized Complete Block Design was used. The cuttings were planted in three positions (horizontal, vertical, and slanting angle) in the nursery containers covered with the polyethene sheet and the planting medium was composed of river sand. Data were collected monthly on the number and height of sprouts while the cutting survival was done at the end of the experiment which was five months). Data were subjected to analysis of variance using GENSTAT 15th Edition while separation of means was performed using the Standard Error of Difference (SED). The results showed that planting orientation was significant on the sprouting of cuttings df=2, F=117.93, p-value=0.001 as well as the survival of cuttings at the end of the experiment, the cuttings which were planted vertically and slanting were higher compared with those planted in horizontal orientation. The ecotypes had a significant effect on the number of sprouts obtained by stem cuttings df=1, F=6.99, p-value=0.012 and the cuttings from the Western region were performed better than those from Coast. It was concluded that vertical or slanting orientations and Western ecotype should be considered before planting this species.

Seed dispersal by duikers in selectively logged rainforests: Overlooked dispersal of an important animal community

Seed dispersal by frugivores is a key process which is necessary for the regeneration of plant communities. The decrease in the abundance of fruit-eating mammals due to anthropogenic pressures impacts on the proper functioning of forest ecosystems.In this study, for the first time we evaluate seed dispersal by duikers (Bovidae, frugivores and the most hunted animals of the rainforests of central Africa: Congo basin), using germination trials of seeds contained in their dung and rumen. The influence of selective timber harvesting on this dispersal was also examined by comparing duiker community occupancy between a logged and an unlogged site.Our results revealed a community of four duiker species Cephalophus silvicultor, Philantomba congica and two species of ‘red’ duiker (C. callipygus and C. castaneus). A total of 79 plant species (5481 seedlings) were found in the dungs of all duikers and a total of 37 species (5225 seedlings) were observed in the rumens of red duikers and P. congica. Phyllanthus sp. and Musanga cecropioides were the dominant taxa in dung and rumen contents respectively. Taxa of high commercial value such as Erythrophleum suaveolens, Milicia excelsa and Nauclea diderrichii were also observed. The lack of a clear difference between the plant communities dispersed by the duiker species (assessed by β-diversity) showed that they play redundancy rather than complementary dispersal roles.Duikers play an underestimated role in the restoration of environments disturbed by logging or shifting cultivation as most of the species observed are pioneer colonizing species. Furthermore duiker communities appear to be affected little by selective logging.

Determination of Optimal Drilling Parameters of Massive Wooden Edge Glued Panels (EGP) and Medium Density Fiberboard using Taguchi Design Method

In this paper, the optimization of computer numerical control (CNC) drilling parameters was conducted using the Taguchi design method on the drilling holes’ inner surfaces roughness (Ra) massive wooden edge-glued panels (EGP) made of spruce (Picea Orientalis Link.), beech (Fagus Orientalis Lipsky), Iroko (Chlorophora excelsa) and Medium Density Fiberboard surfaced with synthetic resin sheet (MDFlam). Three drilling parameters and their effects on Ra were evaluated. These parameters included spindle speed, feed rate, and cutter type. Surface roughness measurements according to ISO 4287 were performed on the inner surfaces of the holes, and Ra values were obtained. An analysis of variance (ANOVA) was performed to identify the significant factors affecting the Ra. Optimum drilling parameter combinations were acquired by analyzing the signal-to-noise (S/N) ratio. It is shown that the most ideal result was obtained with a two flutes cutter (cutter number 2) at 18000 rpm and feed of 1750 mm/minute for in-hole roughness values of the MDFlam test sample. In the drilling operations performed with a double-entry cutter, the lowest roughness values were obtained in all materials.

Characterisation of the Chemical Composition of Aningeria robusta: A. Chev WOOD

The study was carried out to assess the chemical composition of Aningeria robusta wood. Two stands of Aningeria robusta were purposely sampled for felling at The National Forestry Resources Research Institute (NAFORRI), Kifu, Uganda. From each felled tree, samples were taken at the base, middle and top portions of the merchantable height and were later partitioned into core wood, middle wood and outer wood across the radial plane. A split plot statistical method was used to test the significance of the variability in the wood chemical components examined at a 5% level of probability. A followup Duncan Multiple Ranged Test was also carried out to further examine the extent of significance. The results showed that the mean value for cellulose content was 46.78%, with a consistent pattern of variation occurring both along the tree and across the radical plane. Also, a significant effect was noticed radially and axially. The lignin content had a mean value of 22.20%. It ranged from 20.48 to 23.04%, with an increasing pattern of variation from base to top and core wood to outer wood. The extractive content mean value was 5.0%. It ranged from 4.25 to 5.65%, increasing steadily from base to top and from core wood to outer wood. There was significant effect at P=0.05, both along and across the tree. The results obtained from the research study shows that the percentage chemical composition of Aningeria robusta is satisfactory for a typical hardwood species. The chemical components in the main vary in a consistent pattern both in axial and radial directions. The rich cellulose base of A. robusta wood makes it a good potential resource for paper-making furnishing. Therefore, wood Aningeria robusta should be explored for the chemical production of pulp for papermaking. The significant content of extractive in A. robusta also suggests conferment of natural durability to the wood. Hence, A. robusta wood can be recommended for structural application as suitable substitute for such known wood species as Milicia excelsa and Tectona grandis that are fast going into extinction due to over-exploitation.

Management and protection of large old tree species in farmlands: Case of Milicia excelsa in southern Benin (West Africa)

Agroforestry systems are the last refuge habitats for many large old trees. This study assessed the management and the protection of Milicia excelsa (Iroko) trees in agricultural landscape of Dogbo district in southern Benin. A socio-economic survey with 288 respondents combined with an inventory of M. excelsa trees in agricultural lands were carried out. A total of 404 Iroko's trees were geolocated in 10 stands ranging in size from 102 to 1476 ha. The pair correlation function has been used to assess the spatial patterns of Iroko trees. The density of Iroko trees varies moderately from 1.69 ± 0.19 to 0.07 ± 0.02 stems/ha respectively in farmland and landscape with a spatial distribution ranging from gregarious to random - gregarious - random. The diametric structure of Iroko trees presents a bell-shaped appearance with a left asymmetry. The vertical structure shows a bell-like appearance centered on the modal class made up of individuals of height between 14 and 16 m. Timber exploitation (14%), rarefaction of the species and its attribute of sacred tree (98%) are the main motivations for protecting plants in agricultural lands. The medicinal use of the plant parts of Iroko is mainly based on the bark (33%) and leaves (24%). Except the socioeconomic conditions of farmers, the cultural foundations contribute the most to the preservation of M. excelsa in the agricultural lands. Thus, a participatory reforestation program integrating the endogenous values of local populations in the use of agroforestry systems as biological corridors could be successfully implemented. It would allow the preservation of large old trees from the increasing pressure on their populations in the future.

Selected shade tree species improved cocoa yields in low-input agroforestry systems in Ghana

CONTEXTCocoa agroforestry systems differ in the diversity of shade tree species composition. Though cocoa benefits from shade, there is a lack of species-specific information on shade trees that enhance soil fertility and yield. OBJECTIVEWe examined how soil characteristics and cocoa yield were affected by eight commonly retained forest tree species, compared with unshaded control plots over a 3-year period. METHODSUsing 74 circular plots from 10 cocoa farms in the Western region of Ghana, we sampled soils from two random points within each plot. Soil nutrients at the beginning and end of the study were analyzed, and yield was expressed as number of harvested pods and dry weight of beans per hectare. RESULTS AND CONCLUSIONSLevels of soil K and Ca were below recommended values. Although soil available phosphorus (P) was higher in control plots than under shade trees, yield around shade trees were higher than on unshaded plots. Cocoa yield differences between shade tree species and control plots were significant only in the major crop season, but not in the minor crop season. Cocoa yields under Cedrela odorata, Khaya ivorensis, Terminalia superba and Milicia excelsa were significantly higher than on control plots. Hence, the inclusion of specific shade tree species in cocoa agroforestry systems is important to maintain high yields in cocoa systems with low inputs. SIGNIFICANCETo our knowledge, this study presents one of the first attempt to assess the impacts of specific shade tree species on soil characteristics and cocoa yield.

Review of Deforestation in Ugandan Tropical Rainforest Reserves: A Threat to Natural Medicine

Deforestation in Ugandan Tropical Rainforest Reserves as threat to natural medicine is still undocumented. In this study, we reviewed literature on deforestation most especially from 1990-2020 in the Tropical Rainforest Reserves. We examine the trend of deforestation, impact of deforestation on medicinal plant species’ and threatened medicinal plant species in the Tropical Rainforest Reserves in Uganda. Secondary data from National Forestry Authority on deforestation (1990-2020) was analysed to determine the trend of forest deforestation while PubMed®, Google Scholar, and SCOPUS databases were also used to provide information on the threatened medicinal plants. Our results show that there has been an annual incredible decline of 17% in the trend of deforestation both in Tropical Rainforest Reserves (low-stocked and well-stocked). The results of the review also noticed a 0.86 strong positive correlation in the decline of both Tropical Rainforest Reserves. This review also documented 13 medicinal plants as the most threatened in the Ugandan Tropical Rainforest Reserves. The medicinal plants in Uganda include Dioscorea bulbifera, Cytropsis articulata, Prunus africana, Warburgia ugandensis, Entandrophragma utile, Irvingia gabonensis, Spathodea campanulate, Aloe ferox, Vernonia amygdalina, Erythrina abyssinica, Moringa oleifera, Hoslundia opposita Vahl and Milicia excelsa. Our study articulates human activities that are affecting medicinal plants include agricultural expansion, timber harvesting, charcoal burning, firewood harvesting, weak forest policies and laws, un clear forest boundaries infrastructure development e.g., roads.