Khaya Anthotheca Research Articles

Spacing and Genotype on Height and Diameter Growth of Four Eucalyptus Under Short Rotation

In this paper, the dynamic change in tree height, diameter at breast height (dbh), and ground line diameter (gld) at different density was studied. Trial sites were established in Chepkoilel and Nangili areas of western Kenya. Eight tree species (2 hybrid eucalyptus clones; GC 10 and GC 167), 1 eucalyptus local landrace, 2 agroforestry ( Grevillea robusta and Markhamia lutea ), 1 pure eucalyptus ( Eucalyptus grandis ), and 2 preferred local species ( Maesopsis eminii and Khaya nyasica ) were planted on each site. This paper however focuses on the effect of spacing on the height, dbh, and gld growth of the 4 eucalyptus genotypes viz (2 eucalyptus hybrid clones, 1 eucalyptus local landrace, and 1 pure Eucalyptus grandis). These were planted at 10 different spacings (0.6-, 0.8-, 1.0-, 1.2-, 1.4-, 1.6-, 1.8-, 2.0-, 2.2-, and 2.4-by-1.0 m; these being some of the most common spacings used by farmers) in a Nelder radial experimental design in 4 replications. Measurements of height, dbh, and gld were taken at intervals of 6 months over 3 years. The data was subjected to an analysis of variance to determine if there were statistically significant (p = 0.05) differences in tree growth with spacing levels. The results showed that tree growth was significantly influenced by spacing and genotype with the best spacing being 2.4-by-1.0 m, indicated that the relative growth rates of height dbh, gld, and increased with increasing the distance between trees but decreased with age. After 3 years the best spacing for optimal overall tree growth was 2.4-by-1.0 m and GC10 being the outstanding genotype. Of the 2 sites, trees performed better in Nangili. The results from this study further pinpoint the importance of species-site-matching using improved germplasm and planting trees at the correct spacing for optimal growth. Keywords : tree growth, spacing, eucalyptus hybrid clones, short rotation forestry, species site matching

Restoration of degraded dry semideciduous forest ecosystems in Ghana: Effects of African mahogany species on soil chemistry, tree diversity and the application of leaf morphometrics for provisional seed zonation

The dry semideciduous forest zone is one of the most fragile and highly threatened ecosystems in Ghana. Recurrent bushfires and other anthropogenic disturbances have degraded this forest zone and converted a large proportion to savannah woodland. Moreover, the invasion of weeds following disturbances has impeded natural regeneration. Hence, the likely solution to this problem is restoration through the use of native forest tree species to catalyse natural regeneration. The use of African mahogany species in this regard has been emphasised. This study aims to (i) investigate the levels of phenotypic plasticity and ecogeographic and morphometric variation as well as similarity among populations of Khaya anthotheca and Khaya ivorensis with respect to leaf morphology as a basis for developing a preliminary framework for seed zonation for restoration; (ii) determine the effects of stand structure and native tree density on the recruitment of mahogany species in line-enrichment planting; and (iii) assess the effects of mahogany species on resident or native tree species diversity and soil chemical properties in restorations of degraded semi-deciduous forest ecosystems in Ghana. The results of the study indicated a highly significant phenotypically plastic response of leaf morphology to precipitation, temperature, altitude and latitude in Khaya ivorensis populations. In addition, it was established that leaf size in Khaya ivorensis and K. anthotheca varies inversely with latitude, annual potential evapotranspiration and aridity index. However, leaf traits vary directly with a precipitation gradient among the respective species. The results suggested a south-north clinal relationship to leaf traits, with the southern populations of the two Khaya species having larger leaf sizes than the northern populations. Thus, seeds collected from higher latitudes could be planted in the same zone or moved to lower latitude with high amounts of rainfall. However, the results from Poisson regression modelling indicated that stand basal area, growing space and crown diameter were positively associated with recruitment. However, stand dominant height was negatively associated with recruitment. The results indicated that mixed mahogany species foster the recolonisation of a diversity of native tree species and accelerate the regeneration rate in the restoration of fire-degraded dry semi-deciduous forest ecosystems compared to natural regeneration. Moreover, relatively higher amounts of Ca, Mg, base saturation, CEC, organic C and organic matter and low amounts of Al were recorded in the soils beneath mixed mahogany plantation sites compared to natural regeneration sites.

Endophytic fungi isolated from Khaya anthotheca in Ghana

An important African timber tree species, white mahogany (Khaya anthotheca), is heavily exploited and vulnerable. Endophytic fungi are thought to have an important role in plant communities, e.g. by increasing the fitness of the host tree. The aim of the present study was to isolate and characterize endophytic fungi collected from K. anthotheca in Ghana. In total, 64 fungal isolates were obtained from symptomless leaf samples. The fungi were grouped according to their morphology, and subjected to DNA sequence comparisons of the ribosomal ITS region. Based on phylogenetic analyses, the fungal isolates were grouped in Sordariomycetes and Dothideomycetes (Ascomycota). Species of Xylariales were the most common fungi associated with K. anthotheca. The results of this study indicate that K. anthotheca serves as a host to numerous endophytic fungi. These fungi could have significance as a source of novel metabolites, and for the fitness of this tree species.

Water Sorption Isotherm Characteristics of Seeds of Six Indigenous Forest Tree Species in Ghana

The relationship between storage temperature, relative humidity and seed water content was investigated for six indigenous forest tree seed species, namely Garcinia kola, Terminalia superba, Terminalia ivorensis, Mansonia altissima, Entandrophragma angolense and Khaya anthotheca in Ghana. Seeds were equilibrated over a series of lithium chloride solutions with relative humidities ranging from 12 to 93% and silica gel with relative humidity of 3% at 20 ºC. Seeds reached equilibrium with different days depending on seed size and structure, ranging from 13 days for E. angolense to 91 days for G. kola. When seeds equilibrated, moisture contents were determined gravimetrically, and values of moisture contents were then plotted against relative humidity to construct moisture sorption isotherms for the species. Seeds of T. superba, T. ivorensis, M. altissima, E. angolense and K. anthotheca, exhibited a sigmoidal relationship between seed water content and relative humidity indicative of three regions of water binding. Contrarily to other reports, the shape of the isotherm curve for G. kola – a desiccation sensitive species – also showed the reversed sigmoid pattern similar to isotherm curves of orthodox species rather than the monotonic shape. The isotherms showed that seed moisture content increased with increasing relative humidity. Seed samples of G. kola, placed at all relative humidities chambers, lost water(desorption) as the initial water content of 58% was very high and, therefore, possessed a higher water potential than the environments. Seeds of the other species either lost water (desorption) to the relative humidity chambers, or absorbed water from the chambers depending on the relative humidity of the environment they were placed.

Germination résponses of Khaya anthotheca seeds to a range of alternating and constant températures provided by the 2-way Grant’s thermogradient plate

Khaya anthotheca seeds were placed in Petri dishes containing a gel of 1% water agar for germination over a period of 30 consecutive days. Petri dishes were arranged 8 units x 8 units on the 2-way Grant’s thermogradient plate (a bi-directional incubator). The goal of the study was to take a more comprehensive look at germination responses of seeds to a broad range of alternating or constant temperatures on the thermogradient plate. The instrument allows for germination testing of seeds over a wide range of single temperature and alternating temperature regimes over a time continuum, given 64 temperature combinations (regimes) (5 to 40°C). Conditions were 40/40°C (day/night temperature) on the high end of the plate and 5/5 oC on the cool end. Two temperature gradients ranging from 5 to 40°C were used. The first gradient, progressing from left to right on the thermogradient plate in dark, was alternated every 12 hours with the second progressing from front to back of the thermogradient plate with light. The study was repeated twice. Fifteen (15) seeds were used in each replication. The various temperature combinations had significant effect on final germination percentage, mean germination time, time for first germination and rate of germination. Alternating temperatures improved overall germination. The best germination at a constant temperature was at 20/20°C and 30/30°C. The best temperature regimes for seed germination at alternating temperatures were at 5/30°C, 10/30°C,15/30°C, 20/25°C, 20/35°C, 25/15°C, 25/20°C, 25/30°C, 30/20°C, 35/10°C, and 35/15°C.

Chaenothecopsis khayensis, a new resinicolous calicioid fungus on African mahogany

The new species Chaenothecopsis khayensis (Ascomycota, Mycocaliciaceae) is described from Ghana, western Africa, on the resin of Khaya anthotheca and K. ivorensis. The species is distinctive in forming asci without crosiers and in possessing ascospores that are faintly longitudinally striate. Analysis of large subunit rDNA gene sequences positioned this species within a clade corresponding to the Mycocaliciales and identified its closest relative as Sphinctrina leucopoda. Chaenothecopsis khayensis occurs commonly on resin exuding from trees damaged by the larvae of the mahogany shoot borer (Hypsipyla sp.), and we discuss the possible ecological relationship between the fungus and these moths.

Detection of antimicrobial compounds by bioautography of different extracts of leaves of selected South African tree species.

The hexane, acetone, dichloromethane and methanol extracts of Combretum vendae A.E. van Wyk (Combretaceae), Commiphora harveyi (Engl.) Engl. (Burseraceae), Khaya anthotheca (Welm.) C.DC (Meliaceae), Kirkia wilmsii Engl. (Kirkiaceae), Loxostylis alata A. Spreng. ex Rchb. (Anacardiaceae), Ochna natalitia (Meisn.) Walp. (Ochnaceae) and Protorhus longifolia (Bernh. Ex C. Krauss) Engl. (Anacardiaceae) were screened for their antimicrobial activity. The test organisms included bacteria (Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus), and fungi (Aspergillus fumigatus, Candida albicans, Cryptococcus neoformans, Microsporum canis and Sporothrix schenckii). A simple bioautographic procedure, involving spraying suspensions of the bacteria or fungi on thin layer chromatography (TLC) plates developed in solvents of varying polarities was used to detect the number of antibacterial and antifungal compounds present in the extracts. All the extracts had antimicrobial activity against at least one of the test microorganisms. This activity was denoted by white spots against a red-purple background on the TLC plates after spraying with tetrazolium violet. Twenty seven TLC plates; 9 for each solvent system and 3 different solvent systems per organism were tested in the bioautographic procedure. Of the bacteria tested, S. aureus was inhibited by the most compounds separated on the TLC plates from all the tested plants. Similarly, growth of the fungus C. neoformans was also inhibited by many compounds present in the extracts. Loxostylis alata appeared to be the plant extract with the highest number of inhibition bands when compared with other plants tested against both bacteria and fungi. This species was selected for in depth further study.

Evaluation of selected South African plant species for antioxidant, antiplatelet, and cytotoxic activity

The antioxidant, antiplatelet, and cytoxoxic effects of seven South African plant extracts, namely, Combretum vendae A.E. van Wyk (Combretaceae), Commiphora harveyi (Engl.) Engl. (Burseraceae), Khaya anthotheca (Welm.) C.DC (Meliaceae), Kirkia wilmsii Engl. (Kirkiaceae), Loxostylis alata A. Spreng. ex Rchb. (Anacardiaceae), Ochna natalitia (Meisn.) Walp. (Ochnaceae), and Protorhus longifolia (Bernh. Ex C. Krauss) Engl. (Anacardiaceae), were evaluated using established in vitro assays. All the extracts showed comparably low toxicity except for the extract of C. harveyi that showed high hemagluttination assay titer value, which indicates toxicity. The extracts of P. longifolia, K. wilmsii, O. natalitia, L. alata, C. harveyi, and C. vendae exhibited antioxidant properties in the qualitative assay using DPPH. In the quantification of antioxidation using ABTS, only the extracts of P. longifolia, L. alata, and C. vendae showed antioxidant activity with respective TEAC values of 1.39, 1.94, and 2.08. Similarly, in the quantitative DPPH assay, L. alata (EC50, 3.58 ± 0.23 µg/mL) and K. wilmsii (EC50, 3.57 ± 0.41 µg/mL) did not differ significantly (p ≤ 0.05) from the control. K. anthotheca showed a higher EC50 (176.40 ± 26.56 µg/mL) value, and differed significantly (p ≤ 0.05) from all the other extracts and control. In addition, the extracts of C. vendae and C. harveyi showed significant (p ≤ 0.05) antiplatelet activity and did not differ from the control (aspirin) with EC50 of 0.06 ± 0.01 µg/mL and 0.19 ± 0.00 µg/mL, respectively. Lower EC50 values in the antioxidant and antiplatelet studies are indicative of superior activity of the plant extract against oxidation and platelet aggregation.

Evaluation of several tree species for activity against the animal fungal pathogen Aspergillus fumigatus

Aspergillus fumigatus causes severe problems in poultry production systems. Seven South African tree species were selected from the database of the Phytomedicine Programme based on its antifungal activity against the fungus Cryptococcus neoformans. The acetone leaf extracts of the selected species had minimum inhibitory concentrations (MICs) of 0.16 mg/ml and lower in the preliminary screening. The antibacterial and antifungal activities of hexane, dichloromethane, acetone and methanol extracts of the leaves were determined using a two-fold serial microdilution method against a range of commonly encountered animal pathogenic fungi ( A. fumigatus, Candida albicans, C. neoformans, Microsporum canis and Sporothrix schenckii) and four nosocomial bacteria ( Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa). The plant species investigated were Combretum vendae (A.E. van Wyk) (Combretaceae), Commiphora harveyi (Engl.) Engl. (Burseraceae), Khaya anthotheca (Welm.) C.DC (Meliaceae), Kirkia wilmsii Engl. (Kirkiaceae), Loxostylis alata A. Spreng. ex Rchb. (Anacardiaceae), Ochna natalitia (Meisn.) Walp. (Ochnaceae) and Protorhus longifolia (Bernh.) Engl. (Anacardiaceae). All the extracts had activity against at least one of the test organisms over an incubation period of 24 or 48 h. The MIC values of the non-polar and intermediate polarity extracts of O. natalitia, K. anthotheca, C. vendae, C. harveyi, and P. longifolia had MICs as low as 0.08 mg/ml against at least one of the tested bacteria. Furthermore, the acetone extracts of L. alata, K. wilmsii, O. natalitia and C. vendae had antifungal activities with MIC values ranging from 0.04 to 0.08 mg/ml against at least one of the tested fungi. The average MIC values of the plant extracts against the different bacteria ranged from 0.17 to 2.11 mg/ml, while the range was 0.23–1.98 mg/ml for fungi. The Gram-positive bacteria ( S. aureus and E. faecalis) were more susceptible to the plant extracts than the Gram-negative bacteria ( E. coli and P. aeruginosa). E. faecalis was the most susceptible microbe and C. vendae extracts were the most active against nearly all the bacteria tested. The acetone extract of L. alata was the most active against fungal pathogens, with activity against at least 3 fungal organisms. L. alata was selected for further work to isolate compounds active against A. fumigatus and other fungal pathogens.

Properties of Manilkara Discolor (Sond.) Hemsl.): a lesser-known timber species from Kilindi District Tanzania

This work was conducted to determine some physical and mechanical properties of Manilkara discolor , a lesser-known and lesser-utilized timber species from Kilindi District Tanzania. Three large trees free from visible defects were selected, felled and small sample pieces of 20 mm x 20 mm x 60 mm for compression, 20 mm x 20 mm x 20 mm for shear, 20 mm x 20 mm x 45 mm for cleavage and 20 mm x 20 mm x 300 mm for static bending, comprising 72 pieces for each test were prepared. The sample pieces were tested in laboratory using standard methods. The wood was brownish and attractive, fine textured with appealing figure and attaining good finish when plained. The results showed the species to have wood basic Density of 765 kg m-3, Modulus of Elasticity of 14,341 N mm-2, Modulus of Rupture of 119.48 Nmm-2, Work to Maximum Load of 0.132 mm Nmm-2 and Work to Total Fracture of 0.284 mm Nmm-2. The Compression parallel to grain was 41.69 Nmm-2, Shear parallel to grain was 18.65 Nmm-2 and Cleavage Strength was 34.97 Nmm-2. Manilkara discolor wood was found to have desirable values and can be used to substitute other species which are currently in danger of over-exploitation. Key words: Basic density – Tanga - Khaya anthotheca - Pterocarpus angolensis

Plant communities of a semi-deciduous tropical rainforest in north-western Uganda: role of soil and anthropogenic factors

Forest plant communities were described using two floristic data sets (accompanied by data on soil and former management practices) from the Budongo Forest Reserve (BFR), Uganda – a semi-deciduous tropical rainforest. The first data set featured species basal-area data for woody species, while the other data set featured abundance for woody plants of stem diameter ≥ 2.0 cm. Four forest community types: Pseudospondias microcarpa Swamp Forest, Funtumia elastica–Pouteria altissima Forest, Lasiodiscus mildbraedii–Khaya anthotheca Forest, and Cynometra alexandri–Rinorea ilicifolia Forest were distinguished. Each community is characterised by a group of species, however there are a considerable number of species shared by all four communities. The forest communities show clear separation along gradients of screened soil characteristics (i.e. Organic matter, Na, N, Ca, Mg, and Si), corroborating the results suggested by the canonical correspondence analysis (CCA). For the species basal-area data, Axes 1 and 2 of the CCA explained 18 % in species, and 34 % of the variance in species-environment relations. Whereas, for the abundance data, the amount of information accounted for by the first two axes was 25 % and 44 %, in species variance and species-environment relations, respectively. Axis 1 of CCA was strongly correlated with soil nutrients, while Axis 2 was correlated with logging and arboricide treatment. Accordingly we interpret Axis 1 as an edaphic gradient, while Axis 2 is depicting an anthropogenic disturbance gradient.

Key roles of leaves, stockplant age, and auxin concentration in vegetative propagation of two African mahoganies: Khaya anthotheca Welw. and Khaya ivorensis A. Chev

Leaf area, IBA concentration and age of stockplants were all found to be important factors for successful rooting for vegetative propagation using single-node cuttings of the two main African mahogany species: Khaya anthotheca and K. ivorensis. Cuttings with leaf area of 30–50 cm2 had the best rooting percentage and cuttings with about 30 cm2 had the most number of roots per cutting in K. anthotheca. Khaya ivorensis, cuttings with 10–30 cm2 leaf area had the highest rooting percentage. Cuttings collected from 1-year-old stockplants recorded the highest rooting percentage and largest number of roots per cutting. Cuttings from 3-year-old stockplant of the same seeds sources had the lowest rooting suggesting aging negatively impacted rooting ability. The effect of auxin concentration, on rootability was examined with cuttings of K. anthotheca. An IBA concentration of 0.8% was the best exogenous auxin concentration for percentage rooting, number of roots per cutting and the length of the longest root per cutting.

Anatomical characteristics, properties and use of traditionally used and lesser-known wood species from Mozambique: a literature review

Mozambique is a country with vast forestry resources that include native wood species with high commercial value. Thus, the trade of timber as raw material, as well as wooden finished products are commercial options of considerable valuable for the country. This work presents information about anatomical characteristics, physical and mechanical properties and use of some native wood species from Mozambique, namely, Afzelia quanzensis, Androstachys johnsonii, Erytrophleoum suaveolens, Khaya nyasica, Pterocarpus angolensis, Milletia stuhlmannii and the emerging lesser-known species Pericopsis angolensis, Sterculia appendiculata and Sterculia quinqueloba. The study concludes that these Mozambican wood species are similar in several aspects. They are generally described as very hard, dense, having high mechanical strength and durable. The study also concludes that although the lesser-known wood species, S. quinqueloba, has similar properties to the traditionally used one, A. quanzensis, it is less used because of its poorly known properties and potential uses. Thus, further research to determine the properties and suitable end uses of other lesser know species is likely to be beneficial to the country.

Effect of lianas on tree regeneration in gaps and forest understorey in a tropical forest in Ghana

AbstractQuestions:Do lianas alter the relative success of tree species during regeneration? Are the effects of lianas on tree seedlings moderated by canopy openness? How are patterns of biomass allocation in tree seedlings affected by liana competition?Location:Tropical moist semi‐deciduous forest in Ghana.Methods:Seedlings of the trees Nauclea diderrichii (pioneer), Khaya anthotheca (non‐pioneer light demander) and Garcinia kola (non‐pioneer shade bearer) were planted with the lianas Acacia kamerunensis (fast growing) and Loeseneriella rowlandii (slow growing) in large and small gaps (ca. 15% and 8% PAR respectively) and in the forest understorey (ca. 4% PAR). Seedling survival, growth and biomass allocation were measured.Results:Canopy openness moderated the interaction between liana and tree seedlings. The nature of the interaction was both liana and tree species specific and displayed temporal variation. Acacia competition effects were stronger in sites with greater canopy openness. In big gaps, Acacia reduced significantly the biomass of Nauclea by 32% and Khaya by about 50%. Khaya growth in leaf area was five times greater without Acacia, while Nauclea and Garcinia were not affected. Acacia was more plastic than Loeseneriella in response to the environment and the tree species. Our results show that while Loeseneriella, with lower rates of growth, did not affect seedling growth of the three species evaluated, Acacia could alter the relative success of tree species during regeneration.Conclusions:There is evidence that competitive effects by Acacia on tree regeneration through competition could modify tree species capacity to establish. Effects by lianas at the regeneration phase may have important implications for forest management.

Silvicultural systems for plantation mahogany in Africa: Influences of canopy shade on tree growth and pest damage

Overexploitation of the African mahoganies, Khaya anthotheca and K. ivorensis, could lead to their commercial extinction in the near future. Efforts to establish plantations to sustain supply have been discouraged by the shoot borer Hypsipyla robusta Moore. We hypothesized that there is a shade level at which Hypsipyla attack and branching are reduced, but height growth is adequate. We report on the growth of these African mahoganies and Hypsipyla attack under three different forest canopy shade levels: open (55% open sky), medium shade (26% open), and deep shade (11% open). Hypsipyla attack on K. anthotheca was 85%, 11%, and 0% attack in the open, medium, and deep shade treatments, respectively. However, growth in medium and deep shade was slow. Mean tree height for K. anthotheca was 413.8, 126.2, and 54.5 cm in the open, medium and deep shade treatments, respectively. K. ivorensis showed similar trends. The reduced growth under these shade levels limit the use of this strategy for controlling Hypsipyla attack.

Relative susceptibility of four species of African mahogany to the shoot borer Hypsipyla robusta (Lepidoptera: Pyralidae) in the moist semideciduous forest of Ghana

We examined the relative susceptibility of four mahogany species, Khaya ivorensis, Khaya anthotheca, Entandrophragma angolense, and E. utile, to Hypsipyla robusta attack. Seeds were obtained from one to three parent trees for each species. The research was conducted in the moist semideciduous forest zone in Ghana and used a randomized complete block design. Tree height and diameter and height to first branch were measured until 24 months after out-planting in the field. H. robusta damage was assessed by counting the numbers of shoots attacked, branches, and dead shoots. Khaya spp. grew better but experienced more attack than Entandrophragma spp. The relative susceptibility to H. robusta attack, from most to least, of the four species was: K. anthotheca > K. ivorensis > E. angolense > E. utile. At 24 months, the mean number of shoots attacked per tree ranged from 1.0 for an E. utile seed source to 3.6 on for a K. anthotheca seed source. At 15 months, K. anthotheca and K. ivorensis started branching at about 1.5 m, but height of clear trunk increased over time due to self-pruning. As K. anthotheca grew taller, the number of H. robusta attacks per tree declined. This suggested that selection of genotypes and species that are tolerant of H. robusta attack based on infestation of young plants may not be appropriate. Genetic factors more completely reflecting the response of different species and genotypes to H. robusta attack may manifest themselves at later growth stages.

Antimalarial activity of anthothecol derived from Khaya anthotheca (Meliaceae)

Antimalarial activity of anthothecol, a limonoid of Khaya anthotheca (Meliaceae) against Plasmodium falciparum was tested using a [(3)H]-hypoxanthine and 48h culture assay in vitro. Anthotechol showed potent antimalarial activity against malaria parasites with IC(50) values of 1.4 and 0.17microM using two different assays. Also, gedunin had antimalarial activity with IC(50) values of 3.1 and 0.14microM. However, the citrus limonoids, limonin and obacunone did not show any antimalarial activity. The antimalarial activities were compared with the three currently used antimalarial medicines quinine, chloroquinine and artemisinin.

Above- and below-ground competition between the liana Acacia kamerunensis and tree seedlings in contrasting light environments

Proliferation of lianas in canopy gaps can restrict tree regeneration in tropical forests through competition. Liana effects may differ between tree species, depending on tree requirements for above- and below-ground resources. We conducted an experiment in a shade house over 12 months to test the effect of light (7 and 27% external irradiance) on the competitive interactions between seedlings of one liana species and three tree species and the contribution of both above- and below-ground competition. Seedlings of the liana Acacia kamerunensis were grown with tree seedlings differing in shade tolerance: Nauclea diderrichii (Pioneer), Khaya anthotheca (Non-Pioneer Light Demander) and Garcinia afzelii (Non-Pioneer Shade Bearer). Trees were grown in four competition treatments with the liana: no competition, root competition, shoot competition and root and shoot competition. Both root and root–shoot competition significantly reduced relative growth rates in all three tree species. After one year, root–shoot competition reduced growth in biomass to 58% of those (all species) grown in no competition. The root competition treatment had a more important contribution in the effect of the liana on tree growth. Tree seedlings did not respond to competition with the liana by altering their patterns of biomass allocation. Although irradiance had a great effect on tree growth and allocation of biomass, the interaction between competition treatments and irradiance was not significant. Nauclea diderrichii, the tree species which responded most to the effects of competition, showed signs of being pot-bound, the stress of which may have augmented the competition effects. The understanding of the interaction of above- and below-ground competition between lianas and trees and its moderation by the light environment is important for a proper appreciation of the influence of lianas on tropical forest regeneration.

Provenance variation in Khaya species for growth and resistance to shoot borer Hypsipyla robusta

Khaya anthotheca and Khaya ivorensis (trade name African mahogany) of the family Meliaceae are among the most valuable tropical timber tree species of Africa. Continued supply of these timber species is threatened by over exploitation from natural forest and the difficulties in the establishment of mahogany plantations due to attack of shoot borer Hypsipyla robusta Moore. Hypsipyla attack destroys the growing shoots, causes forking, retards growth and reduces the economic value of the timber. In this study, provenance and within provenance evaluation for pest resistance and growth were studied. The results showed no significant ( P > 0.05) variation in growth among provenances of K. anthotheca and K. ivorensis. Significant variations ( P < 0.05) were however observed in growth parementers among progenies of both species. The growth (total height and diameter) of the highest-ranking progenies of the two species were twice those of the lowest-ranking progenies. K. anthotheca had a high heritability ( h 2 = 0.74) for height growth compared to that of K. ivorensis ( h 2 = 0.51) suggesting an inherent degree of higher genetic control in height growth for K. anthotheca than K. ivorensis. The degree of apical dominance and height growth were found to be the most important factors for selection for pest resistance. Backward selection based on the performance of the progenies identified nine and six mother trees of K. anthotheca and K. ivorensis respectively for conservation as seed trees. The results are discussed in relation with productivity in plantations, conservation of genetic resources of mahoganies and the potential of family and or individual selection for quick and high genetic gains.

Some Physical And Mechanical Properties Of Uapaca Kirkiana, A Lesser-Known Timber Species From Tanzania

This study was carried out to determine some physical and mechanical properties of Uapaca kirkiana a lesser known timber species growing in public land near Iyondo Catchment Forest Reserve, Kilombero District, Morogoro, Tanzania. A total of 3 trees were used in the study. Preparation of test samples and laboratory procedure to determine some physical and mechanical properties followed standard methods. Analysis of variance was used to determine the variation between and within trees and regression analysis was used to determine relationship between wood basic density and mechanical properties. The results showed that Uapaca kirkiana has whitish sapwood and dark brown heartwood, with a mean basic density of 518.14 kg/m3. The properties of Uapaca kirkiana were as follows: modulus of elasticity (7185.69 N/mm2), modulus of rupture (59.7 N/mm2), work to maximum load (0.06 mmN/mm3), total work to failure (0.07 mmN/mm3), shear strength parallel to the grain (11.86 N/mm2), compression strength parallel to the grain (34.4 N/mm2) and cleavage strength (20.21 N/mm width). On axial direction, the modulus of elasticity, total work to failure, compression strength parallel to grain and cleavage strength were directly proportional to its basic density while modulus of rupture, work to maximum load and shear strength parallel to the grain were inversely proportional implying that Uapaca kirkiana is suitable for activities, which require high modulus of elasticity, total work to failure, compression strength parallel to the grain and cleavage strength. On radial direction modulus of elasticity, modulus of rupture, work to maximum load, compression parallel to the grain and cleavage strength were directly proportional to basic density while shear parallel to the grain was inversely proportional to basic density. Compared to Khaya anthotheca, the timber species found in the same location and market; it was found that the timber of Uapaca kirkiana had modulus of rupture and compression parallel to the grain far lower than those of Khaya anthotheca, while the work to maximum load, total work to failure, shear strength parallel to grain and modulus of elasticity were almost the same. Due to the similarity in some of their physical and mechanical properties, the wood of Uapaca kirkiana may berecommended to substitute Khaya anthotheca in wood works that require medium density wood like in decoration where colour is considered an important aspect for appearance and in cabinet, panel and furniture making though it is not adequate in high-class strength joinery. TJFNC Vol. 76 2007: pp. 94-101