Lophira Alata Research Articles

The dynamics of ant mosaics in tropical rainforests characterized using the Self‐Organizing Map algorithm

Ants, the most abundant taxa among canopy-dwelling animals in tropical rainforests, are mostly represented by territorially dominant arboreal ants (TDAs) whose territories are distributed in a mosaic pattern (arboreal ant mosaics). Large TDA colonies regulate insect herbivores, with implications for forestry and agronomy. What generates these mosaics in vegetal formations, which are dynamic, still needs to be better understood. So, from empirical research based on 3 Cameroonian tree species (Lophira alata, Ochnaceae; Anthocleista vogelii, Gentianaceae; and Barteria fistulosa, Passifloraceae), we used the Self-Organizing Map (SOM, neural network) to illustrate the succession of TDAs as their host trees grow and age. The SOM separated the trees by species and by size for L. alata, which can reach 60 m in height and live several centuries. An ontogenic succession of TDAs from sapling to mature trees is shown, and some ecological traits are highlighted for certain TDAs. Also, because the SOM permits the analysis of data with many zeroes with no effect of outliers on the overall scatterplot distributions, we obtained ecological information on rare species. Finally, the SOM permitted us to show that functional groups cannot be selected at the genus level as congeneric species can have very different ecological niches, something particularly true for Crematogaster spp., which include a species specifically associated with B. fistulosa, nondominant species and TDAs. Therefore, the SOM permitted the complex relationships between TDAs and their growing host trees to be analyzed, while also providing new information on the ecological traits of the ant species involved.

Neurobehavioural evaluation of Lophira alata (Ochnaceae) stem bark extract in mice.

Stem bark and leaves of Lophira alata (Family: Ochnaceae) have been used traditionally for their anti-psychotic, anti-convulsant and anxiolytic properties. Since no existing data was found on the neurobehavioural properties, this study was carried out to evaluate some neurobehavioural properties of the aqueous extract of the stem bark of L. alata in animal models. The oral mean lethal dose (LD50) of the extract was estimated, and preliminary phytochemical screening was conducted. Lophira alata extract (200, 400 and 800 mg/kg, p.o.) was investigated for antidepressant effect using the forced swim and tail suspension tests, and the anxiolytic potential was assessed using the stair case and hole board tests. Pentylenetetrazole-induced convulsion test was used to investigate the anticonvulsant potential of the extract. The LD50 was estimated to be >5000 mg/kg. Oral administration of L. alata extract produced a significant (p<0.05) non-dose-dependent decrease in the period of immobility in both the forced swim and tail suspension tests. While a significant decrease (p<0.05) in episodes of grooming was recorded in the staircase test, the number of head dips was not significantly reduced (p>0.05) in the hole board test. In the pentylenetetrazole-induced convulsion, a non-dose-dependent increase in onset of tonic-clonic seizures and protection from death was recorded. The results obtained suggest that the aqueous stem bark extract of L. alata possesses neurobehavioural properties which may account for its use in ethnomedicine.

Probabilistic Evaluation of Eurocode 5 Fire Design Criteria of a Timber Portal Frame

Structural reliability analysis for a three-hinge timber portal frame subjected to fire was undertaken. Eight modes of failure were identified for the frame and limit state function was formulated for each failure mode. The limit state functions were based on the Eurocode 5 design criteria. Uncertainties in the timber material properties were generated from laboratory test results performed on five commonly used timber species in Nigeria, namely Alstonia boonei (Ahun), Triplochiton Scleroxylon (Obeche), Terminalia Ivorensis (Idigbo), Terminalia superba (Afara) and Lophira Alata (Ekki). Uncertainties in loading and geometrical properties were obtained from international references. The limit state functions were evaluated using nonlinear constrained optimization technique. The optimization was executed using Genetic Algorithms(GA) based First Order Reliability Method (FORM) algorithm, through a developed computer programme in MATLAB. The results indicated that, the predominant mode of failure for a three-hinged timber portal frame in fire is the failure of the rafter-column connection that resulted to least safety levels for all the considered fire exposure times. Also, it was observed that at the critical mode of failure the portal frame can sustain fire for up to 50 minutes before failure, however, the target safety index of 3.8 recommended in the Eurocode can only be achieved at fire exposure time less than or equal to 25 minutes. http://dx.doi.org/10.4314/njt.v34i1.5

Ethnobotanical Survey, Antimicrobial and Anticomplement Activities of Guinean Medicinal Plants Traditionally Used in the Treatment of Inflammatory Diseases in Conakry and Dubreka

Based on an ethnobotanical survey related to inflammatory diseases, 67Guinean plant species belonging to 35 botanical families were inventoried. Some plant species frequently used in the treatment of rheumatism, skin diseases and microbial infections were selected and submitted to a biological investigation including antimicrobial and anticomplement activities. At a concentration of 1mg/ml, all the tested extracts were devoid of any activity against the tested fungi viz Candida albicans, Aspergillus niger, and Trichophyton rubrum and showed a cytotoxicity varying from 0.25 to 500 µg/ml which prevented the evaluation of possible antiviral effects against herpes simplexvirus type 1, Coxsackie-B2, Measle Edmondston A, Poliomyelitis virus type 1, Semliki forest L10 and Vesicular stomatitis virus for viruses. At 1mg/ml, only the extracts ofAgeratum conyzoides, Alchornea cordifolia, Acanthospermum hispidum, Erythrina senegalensis, Harungana madagascariensis, Hymenocardia acida, and Lophira alata showed an antibacterial effect against Bacillus cereus and/or Staphylococcus aureus. All the tested extracts exhibited an inhibitory effect on the Alternative Complement Pathway complement except for Bambusa vulgaris. Only the extracts of Ageratum conyzoides and Hymenocardia acida interfered with both activation pathways of the complement system. The results of the present work support the anti-inflammatory traditional use of some selected plant species which could be explained, at least partly, by their anticomplement properties.

Characterization of Selected Nigerian Biomass for Combustion and Pyrolysis Applications

Biomass is the most utilized form of renewable energy, especially in developing nations, and is a possible replacement for fossil fuel in power generation. The most commonly used method for recovering energy from biomass is combustion. Many countries are exploring the utilization of energy crops and indigenous residues to deliver sustainable sources of biomass. For these bio-resources, detailed characterization of the fuel properties is essential in order to optimize the combustion processes. In this study, some potential energy crops and woods from Nigeria, namely Terminalia superba, Gmelina arborea, Lophira alata, Nauclea diderrichii, and also one abundant agricultural residue, palm kernel expellers (PKE), were characterized for their combustion properties. Standard characterization methods such as proximate and ultimate analyses, metals analysis, and ash fusion test were used for this purpose and the results were compared with some U.K. biomass. In addition, their thermal conversion was assessed by thermogravimetric analysis and pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS). Finally, combustion studies were conducted by suspending single biomass particles in a methane flame to obtain information on reactivities and combustion characteristics. Results indicate that the ash fractions in the Nigerian woods were low in K, Si, and Ca, resulting in low calculated alkali indices, hence these fuels are not predicted to cause severe fouling problems. Furthermore, the analysis of the evolved product during devolatilisation from Py–GC–MS suggests that the content of oil is high in Gmelina. Finally, the results from the single particle combustion experiments revealed a longer char burn out rate for Lophira and Nauclea when compared with those of Terminalia and Gmelina.

Anti‐depressant, cognitive, anxiolytic and anti‐convulsant evaluation of Lophira alata (Ochnaceae) stem bark in mice (LB629)

Background: Stem bark and leaves of Lophira alata (Family: Ochnaceae) have been used traditionally for their anti‐psychotic, anti‐convulsant, analgesic and sedative properties.Objective/Aim: The study was carried out to evaluate some neuropharmacological properties of the aqueous extract of the stem bark of Lophira alata in animal models.Methods: Anxiolysis, depression, anti‐convulsion, memory and cognition were evaluated using animal models of these central nervous system indices.Results: Oral administration of Lophira alata extract (200‐800mg/kg) caused a significant (p&lt;0.05) non‐dose dependent increase in the period of vigorous activity in both the forced swim and tail suspension tests. In the novel object recognition test, administration of the extract resulted in a positive discrimination index score; spontaneous alteration performance was slightly enhanced in the Y‐maze test. While significant decrease (p&lt;0.05) in upwards climbs in the staircase test was recorded, number of head dips were not significantly reduced (p&gt;0.05) in the hole board test. In the Pentylenetetrazole induced convulsion, a non‐dose dependent increase in onset of tonic‐clonic seizures and modest protection from death was recorded. These effects were comparable to standard drugs‐Imipramine, Diazepam, Scopolamine and Phenobarbitone.Conclusion: The results obtained suggest that the aqueous stem bark leaf extract of Lophira alata possesses neuropharmacological properties which may account for its use in Ethnomedicine.Grant Funding Source: Supported by personal funds

Diagnosing the demographic balance of two light-demanding tree species populations in central Africa from their diameter distribution

The diameter distribution of a tree species population in a natural forest reflects its demographic dynamics and the impact of past disturbances. A modal diameter distribution can be the mark of a demographic imbalance or it can be the consequence of a particular growth pattern. By comparing the observed diameter distribution with the one that follows from a reference growth model under the hypothesis of demographic balance, we diagnosed demographic balance. In a forest concession in Gabon before logging, an unbalanced diameter distribution was found for Aucoumea klaineana, a long-lived pioneer species and also a valuable commercial species. The Aucoumea klaineana population consisted of old trees without meaningful recruitment, thus indicating an ageing, declining population. In contrast, in the same concession, a balanced diameter distribution was found for Lophira alata, a pioneer to moderate light-demanding species. The history of this forest concession, once heavily populated and subsequently depleted from human perturbation (shifting cultivation), can be used to interpret these demographic statuses. These results reinforce the view of a forest that is constantly changing and shaped by past human perturbations, with the implication for its conservation that some kind of perturbation should be maintained.

Cytotoxic, Antimutagenic, and Antioxidant Activities of Methanolic Extract and Chalcone Dimers (Lophirones B and C) Derived From Lophira alata (Van Tiegh. Ex Keay) Stem Bark

The cytotoxic, antimutagenic, and antioxidant activities of methanolic extract and lophirones B and C derived from Lophira alata stem bark were evaluated. The extract and lophirones B and C significantly (P < .05) reduced the viability of Ehrlich ascites carcinoma cells. There were concentration-dependent reduction in 4-nitro-o-aminophenylenediamine and benzo[a]pyrene-induced frame shift mutation as well as aflatoxin B1-induced base pair substitution by the extract and lophirones B and C. The extract and lophirones B and C concentration dependently scavenged DPPH radical, superoxide anion radical, hydrogen peroxide, hydroxyl radicals, and reduced ferric ion in the potassium hexacyanoferrate III reducing system. The results obtained from this study revealed that methanolic extract and lophirones B and C derived from Lophira alata stem bark posses anticancer, antimutagenic, and antioxidant activities, with lophirone C producing the best anticancer, antimutagenic, and antioxidant activities. The acclaimed anticancer activity of Lophira alata may be attributed to lophirones B and C.

Un modèle de croissance pour l'azobé, Lophira alata, au Gabon

L'azobé, Lophira alata, est un important bois d'oeuvre d'Afrique centrale classé vulnérable dans la liste rouge de l'UICN. Bien que de nombreuses mesures de croissance aient été faites pour cette espèce, aucun modèle de croissance ne semble exister actuellement. L'objectif de ce travail était de faire la part, dans la croissance de l'azobé, entre l'effet de la taille de l'arbre et celui de la compétition locale. Un modèle de croissance a été ajusté pour l'azobé en utilisant les données de quatre sites de mesures au Gabon. Ce modèle de croissance a été conçu pour être utile à l'aménagement forestier, c'est-à-dire qu'il ne repose que sur des variables qui peuvent être calculées à partir des données d'inventaire forestier. Un modèle log-normal avec une réponse négative à la densité du peuplement et à sa surface terrière a été sélectionné. La relation entre la croissance et la taille de l'arbre était unimodale avec un maximum à 60 cm de diamètre à hauteur de poitrine. Un effet résiduel significatif du statut social de l'arbre a été trouvé (avec une croissance plus lente pour les arbres dominés) tandis qu'aucun effet résiduel du site n'a été trouvé.

Correlates of the yield of chemical pulp, lignin and the extractive materials of tropical hardwoods

The aim of this investigation is to correlate the percentage yields of pulp of twenty tropical hardwood species with their lignin and extractive contents. The hardwoods studied include Abura (Hallea ciliata), Afara (Terminalia superba), Agba (Entada gigas), Akomu (Pycnanthus angolensis), Akun (Uapaca guineensis), Eki-Eki (Lophira alata), Erimado (Ricindendron heudelotii), Erun-obo (Erythropleum suaveolens), Iroko (Milicia exelsa), Itako (Strombosia pustulata), Itara (Sacoglottis gabonensis), Mahogany (Khaya ivorensis), Masonia (Masonia altissima), Obeche (Triplochiton scleroxylon), Odoko (Ipomoea asarifolia), Ofun (Avicennia germinans), Okilolo (Symphona globulifera), Opepe (Nauclea diderrichii), Oporoporo (Pterygota macrocarpa) and Some (Ceiba pentadra). Hardwood species such as H. ciliata, T. superba and S. globulifera that gave pulp yield of 50% were found to have the lowest lignin contents in the range of 19.0 to 28.4% and extractives contents of 4.8 to 6.0%. The results obtained showed that there is significant negative correlation (p < 0.01 and r = -0.84) between the percentage pulp yield and the lignin contents as well as between percentage pulp yield and contents of extractive materials (p < 0.01, r = -0.811). However, a significant positive correlation (p < 0.01, r = 0.649) between the percentage lignin contents and the extractive components of the wood samples was observed. The chemical integrity of the pulp, lignin and extractive contents of the wood samples was confirmed by infra-red (i.r.) spectroscopic studies. Key words: Tropical hardwood species, pulp yield, lignin content, extractives.

The effects of different concentrations of indole-3-butyric acid (IBA) on leafy stem cuttings of four tropical timber species

The effects of different concentrations of indole-3-butyric acid (IBA) on the rooting of leafy stem cuttings of Albizia zygia, Blighia welwitschii, Lophira alata andPterocarpus soyauxii were investigated using non-mist propagators. Four hormone concentrations were used; 16000, 8000, 4000 and 0 µg ml-1 (control). Results indicated that Albizia, Blighia and Lophira cuttings rooted best when treated with 16000 µg ml-1 IBA (80, 100 and 40% respectively) and their control cuttings did not root. Pterocarpus stem cuttings treated with 8000 and 4000 µg ml-1 had 100% rooting while those treated with 16000 µg ml-1 and control was 80%. The highest root number was noted in cuttings of the various species treated with 16000 µg ml-1IBA and there were significantly differences only from treatments of Blighia andPterocarpus species. Stem cuttings treated with IBA at 16000 µg ml-1 also gave the fastest rooting time which ranged from 18 to 78 days. Stem cuttings of Blighia,Albizia and Lophira species treated with16000 µg ml-1 IBA also had the longest roots (2.48, 1.23 and 1.45 cm respectively). The longest root length of Pterocarpuswas observed in cuttings treated with 8000 µg ml-1 of IBA (3.72 cm). Vegetative production of seedlings of these species is essential for reforestation programmes. Key words: Timber species, indole -3- butyric acid, leafy stem cuttings, rooting time, percentage rooting.

Growth response of Pterocarpus soyauxii and Lophira alata seedlings to host soil mycorrhizal inocula in relation to land use types

Deficiency in mycorrhizal inoculum in soils due to land use types (LUT) can be alleviated by quantity and quality inoculum addition. A bioassay was carried out to determine how host soil mycorrhizal inoculum influenced mycorrhizal colonization, carbon allocation and partitioning of seedlings of two native timber species of Cameroon humid forest. Seedlings ofPterocarpus soyauxii and Lophira alata were raised for six months on surface soils (0 - 20 cm) collected from early secondary forests and LUT derived from slash-and-burn agriculture and selective logging. Mycorrhizal inoculation effect (MIE) was derived. Seedlings were mainly colonized by members of the Glomaceae and Gigasporaceae, respectively, as shown by molecular typing. They generally performed poorly in soils with indigenous inoculum. But addition of soil inoculum from P. soyauxii trees favored nodulation, significantly increased mycorrhizal colonization and total biomass but decreased root-to-shoot ratios, resulting in large and positive MIE, irrespective of LUT. ln contrast, host soil inoculum of L. alata did not affect fractional mycorrhizal colonization but significantly increased total biomass and resulted in high carbon allocation to roots in low and sometimes negative MIE. Therefore, seedlings' responses to mycorrhizal inoculum depend on host soil inoculum and that could be critical for successful rejuvenation of tropical trees. Key words: Arbuscular, mycorrhiza-host, soil, inoculum-Iand use types, Pterocarpus soyauxii, Lophira alata, Cameroon.

Growth response of &lt;i&gt;Pterocarpus soyauxii&lt;/i&gt; and &lt;i&gt;Lophira alata&lt;/i&gt; seedlings to host soil mycorrhizal inocula in relation to land use types

Deficiency in mycorrhizal inoculum in soils due to land use types (LUT) can be alleviated by inoculum addition. Inoculum effects may depend both on quantity and on quality of inoculum applied. A greenhouse bioassay was carried out to determine the effect of host soil mycorrhizal inoculum on mycorrhizal colonization, carbon allocation and partitioning of seedlings of two native timber species of Cameroon humid forest, raised on surface soils (0-20 cm) collected from early secondary forests, LUT derived from slash-and-burn agriculture and selective logging. Host soil mycorrhizal inoculum was collected from the root zones of con-specific tree species. Mycorrhizal inoculation effect (MIE) was estimated as percent difference of average total biomass between seedlings grown on inoculated and non-inoculated soils. Six months-old seedlings of Pterocarpus soyauxii and Lophira alata were mainly colonized by members of the Glomaceae and Gigasporaceae, respectively, as shown by molecular typing. They generally performed poorly in soils with indigenous inoculum. But addition of soil inoculum from P. soyauxii trees favored nodulation, significantly increased mycorrhizal colonization and total biomass but decreased root-to-shoot ratios, resulting in large and positive MIE, irrespective of LUT. ln contrast, host soil inoculum of L. alata did not affect fractional mycorrhizal colonization but significantly increased total biomass, resulted in high carbon allocation to roots, in low and sometimes negative MIE. Therefore, seedlings' responses to mycorrhizal inoculum depend on host soil inoculum and that could be critical for successful rejuvenation of tropical trees. Key words. Arbuscular mycorrhiza-host soil inoculum-Iand use types- Pterocarpus soyauxii-Lophira alata -Cameroon

Isoflavonoid Derivatives from Lophira alata Stem Heartwood

Six isoflavonoid derivatives among which three are new have been isolated from the stem heartwood of Lophira alata. The structures were elucidated from spectroscopic and chemical evidences. Two have unusual carbon skeletons, possibly resulting from a variant of isoflavonoid biogenesis. The two compounds form the first members of a new subclass of flavonoid compounds which we call "isobiflavonoids". The presence of these isoflavonoid compounds in this plant of the Ochnaceae family has important chemotaxonomic implications since it modifies the botanic distribution of isoflavonoid compounds in non-leguminous plants.

Isoflavonoid Derivatives from Lophira alata Stem Heartwood

Isoflavonoid Derivatives from Lophira alata Stem Heartwood

Isoflavonoid Derivatives from Lophira alata Stem Heartwood

Isoflavonoid Derivatives from Lophira alata Stem Heartwood

Properties Of 10 Ghanaian High Density Lesser-Used-Species Of Importance To Bridge Construction – Part 2: Mechanical Strength Properties

Logs from sixty trees of ten high density Lesser Used Species (LUS) of potential importance to bridge construction were extracted from four forest reserves - Bobiri, Pra-Anum, Nueng, and Subri River in four different ecological zones. The logs from the trees were converted on a horizontal bandmill to 27 and 53 mm thick boards. One-half of the boards were used in the green state and the other half air dried. Mechanical strength test specimens were prepared and tested in accordance with the British Standard BS 373:1957. The range of mean strength values in N/mm2 in the ‘green’ [and dry] conditions for the ten wood species were as follows: - Modulus of Rupture: 69-132 [104-188], Modulus of Elasticity: 7,970-13,740 [9,740- 17,620], Compression parallel to grain: 31-63 [54-92], Shear parallel to grain: 8.8-22.1 [15.1-15.1], and Hardness in kN: 3.5-11.3 [5.1-17.0]. The 10 species in decreasing order of strength was as follows: Lophira alata (Kaku) > Cynometra ananta (Ananta) > Strombosia glaucescens (Afina) > Celtis mildbraedii > Nauclea diderrichii (Kusia) = Celtis zenkeri ~ Piptadeniastrum africanum (Dahoma) > Nesogordonia papaverifera (Danta) > Combretodendron africanum (Essia) > Sterculia rhinopetala (Wawabima). Mean ratios of dry to ‘green’ MOR and MOE were 1.44 and 1.28. There was a good correlation (84.4~98.2%) between the Density (X) and the various mechanical strength values (Y). Regression equations in the form: Y = aXb were derived with R2 values of 0.72-0.93.Keywords: High Density Species, Bridge Construction, Mechanical Strength Properties

Properties Of 10 Ghanaian High Density Lesser-Used-Species Of Importance To Bridge Construction – Part 1: Green Moisture Content, Basic Density And Shrinkage Characteristics

Sixty trees of ten high density Lesser Used Species (LUS) of potential importance to bridge construction were extracted from four forest reserves - Bobiri, Pra-Anum, Nueng, and Subri River (in four different ecological zones). Logs from the trees were converted on a horizontal bandmill to 27 and 53 mm thick boards. Specimens were prepared from the green boards for the determination of the green moisture content, basic density, and dimensional shrinkage of each of the ten species: Celtis mildbraedii, Celtis zenkeri, Combretodendron africanum (Essia), Cynometra ananta (Ananta), Lophira alata (Kaku), Nauclea diderrichii (Kusia), Nesogordonia papaverifera (Danta), Piptadeniastrum africanum (Dahoma), Strombosia glaucescens (Afina), and Sterculia rhinopetala (Wawabima). Mean green moisture content was lowest in Kaku (45%) and highest in Celtis zenkeri (93%). Mean basic density was highest in Kaku (840 kg/m3) and lowest in C. zenkeri (560 kg/m3). Mean green moisture content and mean basic density of the species negatively correlated with a correlation coefficient of -0.87. Mean total tangential shrinkage varied from a low of 6.2% for Dahoma to a high of 9.9% for Kaku. Based on the mean tangential shrinkage from green to 12% moisture content the dimensional shrinkage of the species were classified as ‘small’ for Dahoma, Kusia, Ananta and Danta; ‘medium’ for Celtis mildbraedii, Afina, C. zenkeri, Essia and Kaku; and ‘large’ for Wawabima. Tangential to radial shrinkage (T/R) ratio was ‘very low’ in Kaku, ‘low’ (or fairly close to 1.5) in Danta, Afina, C. zenkeri and C. mildbraedii, ‘pronounced’ (> 1.5) in Ananta and Dahoma; and ‘very pronounced’ (>> 1.5) in Kusia, Wawabima and Essia. The pronounced differential shrinkage ( = 1.5) in these woods is likely to cause wide splits, checks and distortions if precautions are not taken during the kiln drying of these heavy wood species. Total longitudinal shrinkage was excessive and exceeded the normal figure of 0.2% in all ten species, and was higher than the rare figure of 0.4% in Kaku and Ananta.Keywords: High Density Species, Bridge Construction, Green Moisture Content, Basic Density, Shrinkage

Natural Regeneration Potentials Of Some Indigenous Timber Species In An Exploited Plantation Site At Sapoba, Benin City, Nigeria

Seedlings and saplings of economic timber species encounted within an area of 4,000m2 at Sapoba, Edo State (which was previously a plantation site for Entandrophragma cylindricum, Khaya ivorensis and Lovoa trichilodes, established between 1930 and 1932, but were completely exploited between 1990 and 1992) were assessed in order to find out the economic timber species that had regenerated naturally within that land space. The results showed that only 18 choice timber species were encounted within the land area. Gossweilerodendran balsamifera, was significantly (p ≤ 0.05) the most abundant species (42.0%), while the Meliaceae and the Leguminaseae were significantly the most abundant families (p ≤ 0.05)encounted. These were Meliaceae: Entandrophragma angolense(16.5%), Lovoa trichiliodes(8.3%), khaya ivorensis (5.2%) , Entandrophragma cylindricum(3.4%), Guarea cedrata(2.0%), and G. thompsonii(1.0%) and Leguminosae. Albizia ferruginea (3.0%), A. lebbeck (0.6%), Berlinia grandiflora (1.0%), Daniela ogea (0.9%). Piptadeniastrum africana (4.2%) and G. balsamiferam (42.0%). Other species in other families encounterted were Antiaris africana (3.2%), Celtis zenkeri (0.8%), Diospyros mespiliformis (1.00%), Lophira alata (3.2%), Pycannthus angolensis (3.5%) and Terminalia ivorensis (0.5%). Collar diameter correlated significantly and positively with height (r =0.77), showing that generally, the taller the individual stem the larger the collar diameter. The significance of these findings in relation to conservation and management of the choice indigenous timber species to restore them to their pride of place both in Nigeria and abroad.

Timber Production In The Dense Humid Forest Of Cameroon

About 60% of all timber exploited in Cameroon is made of a few species, namely, Triplochiton scleroxylon (Ayous), Entandrophragma cylindricum (Sapelli), Lophira alata (Azobe), Baillonella toxisperma (Moabi), Afzelia bipindensis (Red Doussie) and Afzelia pachyloba (White Doussie).Triplochiton scleroxylon is the most highly exploited timber species in Cameroon reaching a volume of 608,599m3 from the East province in 2004, followed by Entandrophragma cylindricum (403,942m3 in 2001) still from the East Province. For the period 1998 to 2004, the volume of timber of these species exploited fluctuated from year to year, with no steady increase or decrease. This was probably as a result of the uncertainty of their availability even though logging companies open up unexploited areas in search of more timber. The highest volume of timber for most of these species came from the East province, followed by the South and then Centre, except Afzelia pachyloba with highest volumes for this period (24,396m3 in 1999) coming from the Centre province. It is possible that these species have been logged out in areas closer to the ports of export and, so logging companies go further (East and South provinces) to find timber of these species.