Adzo Dzifa Kokutse

Decay resistance of Togolese teak (Tectona grandis L.f) heartwood and relationship with colour

Togolese teak (Tectona grandis L.f) is highly resistant to pathogen attack, but variability in natural durability exists between trees of different ages, plantations and geographical zones. Therefore, further information concerning this parameter of wood quality is necessary; however, traditional testing methods are difficult and time-consuming to carry out. We tested the possibility of using colorimetry to determine durability in heartwood samples taken from a wide range of trees. Twelve hundred samples from 31 trees were exposed to four fungi: Pycnoporus sanguineus, Antrodia sp., Gloephylum trabeum, and Coriolus versicolor. Wood samples were grouped into three classes (inner, intermediate and outer heartwood). The colour parameters of each sample were then determined using the CIELAB (L*, a*, b*) system and results correlated with the %mass loss of wood after fungal attack. Tests showed that Antrodia sp. and C. versicolor resulted in <20% mass loss, whereas all samples were rated as durable or highly durable with regard to P. sanguineus and G. trabeum. Inner heartwood was found to be the most resistant to pathogen attack and outer heartwood the least. Measurements of colour showed that heartwood was lightest nearest the pith and darkness and redness increased towards the outer heartwood. Regressions of lightness with %mass loss in the durability tests were always highly significant, whereas a* and b* were not always significantly regressed with %mass loss. Therefore, the use of colorimetry as a tool to estimate short-term natural durability both rapidly and cheaply could be considered in the case of plantation grown teak wood.

Which factors most influence heartwood distribution and radial growth in plantation teak

Abstract• To investigate the effect of climate on radial growth in young plantation grown teak (Tectona grandis L.), growth ring width was measured in 105 trees and correlated to precipitation and temperature data.• The social status of trees within the stand was also determined and cross-sectional area (CSA) for the trunk correlated to the proportion of heartwood (HW) within the tree. HW develops asymmetrically in leaning stems of some conifer species, but it is not known if this phenomenon also occurs in broadleaf species. Therefore, we measured HW proportion in leaning and straight stems, along with the number of growth rings in the HW.• Annual ring width depended strongly on mean monthly temperature during the rainy season and the most significant relationships were found corresponding to the months of June and July. With regard to the weaker relationship between precipitation and radial growth, correlations were highest during the period of bud-break at the beginning of the rainy season.• The very high stand density affected radial growth, particularly in suppressed trees, which responded little to thinning operations. HW formation was greatest in dominant trees, and was highly regressed with stem CSA.• Therefore, rapid growth of young stands should be encouraged by reducing stand density. Asymmetric HW formation occurred in both leaning and straight trees, and was significantly greater along the upper sides of leaning stems. It is probable that this eccentric HW formation is linked to mechanical loading on the tree.Résumé• Afin d’analyser l’effet du climat sur la croissance radiale des arbres dans les plantations de teck, la largeur de cernes a été mesurée sur 105 arbres. Les données pluviométriques et de température ont été corrélées aux largeurs de cernes mesurées.• Le statut social des arbres à l’intérieur du peuplement a été déterminé et l’aire de la section transversale des troncs a été mise en relation avec la proportion du bois de cœur (HW) formé. Le bois de cœur peut se développer de manière asymétrique chez les espèces de conifères, mais la formation de bois de cœur excentré n’est pas signalée chez les espèces feuillues. Ainsi la proportion de HW dans le tronc a été mesurée chez les arbres droits et penchés, ainsi que le nombre de cernes de l’aubier (SW) transformé en HW.• Les résultats ont montré que la largeur des cernes dépend fortement des températures durant la saison pluvieuse. Les meilleures corrélations entre la croissance radiale et la température sont celles des mois de juin et de juillet. La largeur des cernes est plus faiblement dépendante de la pluviométrie et les corrélations obtenues sont élevées aux périodes d’ouverture des bourgeons, au début de la saison des pluies.• La forte densité du peuplement affecte la croissance radiale, particulièrement chez les individus dominés, qui réagissent très peu aux opérations d’éclaircies. La proportion du HW est plus importante chez les arbres dominants et est fortement corrélée au diamètre du tronc.• Par conséquent la croissance rapide des jeunes peuplements devrait être encouragée en réduisant leur densité. La formation du HW excentré se produit aussi bien chez les arbres droits que penchés. La proportion de HW est significativement plus importante du côté supérieur des troncs penchés, sans doute en raison du chargement mécanique sur l’arbre.

Rapid prediction of shrinkage and fibre saturation point on teak (Tectona grandis) wood based on near-infrared spectroscopy

Abstract• Dimensional stability, along with the natural durability and colour of the wood, is one of the most important characteristics of teak used as timber. However, it is very time-consuming to take measurements of this kind. For the purposes of selection for the production of improved varieties, the number of samples to be measured rapidly exceeds the capacity of a traditional laboratory.• Near-infrared spectroscopy, based on a set of reference data, is a tool enabling many of the chemical properties of wood to be predicted and the number of laboratory measurements to be reduced exponentially. The issue here is a question of checking the effectiveness of NIRS tool to build models and predict the shrinkage and fibre saturation point of teak wood from Togo.• The results show the possible use of NIRS to measure the dimensional stability of teak wood and that it is appropriate to choose the type of wood and type of surface to be measured by NIRS. The best prediction models for radial and tangential shrinkage and fibre saturation point give R2 values of 0.72, 0.83 and 0.87 respectively with ratios of performance deviation of 1.8, 2.4 and 2.8.• Consequently, after verification on other sets of teak samples, which may or may not be included in the prediction model, NIRS can be used to predict shrinkage and fibre saturation point values accurately for a large number of samples, making it possible to include these characteristics in the selection criteria for classifying wood and high throughput phenotyping.Résumé• La stabilité dimensionnelle avec la durabilité naturelle et la couleur du bois, est l’une des plus importantes caractéristiques pour le teck utilisé en bois d’œuvre. Néanmoins, les mesures de ce caractère sont longues et coûteuses en temps. Pour les besoins de la sélection pour la production de variétés améliorées, le nombre d’échantillons à mesurer devient vite supérieur aux capacités d’un laboratoire traditionnel.• La spectroscopie proche infrarouge, sur la base d’un jeu de données de références, est un outil qui permet de prédire de nombreuses propriétés chimiques du bois et de réduire le nombre de mesures de laboratoire de façon exponentielle. La question ici est de vérifier l’efficacité de l’outil NIRS pour construire des modèles et prédire les retraits et le point de saturation des fibres du bois de teck provenant de plantations du Togo.• Les résultats démontrent la possible utilisation de la SPIR pour mesurer la stabilité dimensionnelle du bois de teck et qu’il a y lieu de choisir le type de bois et le type de face que l’on mesure par SPIR. Les modèles de prédiction pour les retraits radial et tangentiel et le point de saturation des fibres montrent des R2 de 0,72, 0,83, 0,87 respectivement avec des rapports d’efficacité de 1,8, 2,4 et 2,8.• En conséquence, et après vérification sur d’autres jeux d’échantillons de teck, qu’il conviendra ou non d’intégrer dans le modèle de prédiction, la SPIR permet de prédire des valeurs de retrait et de PSF avec efficacité pour un grand nombre d’échantillons rendant possible l’intégration de ces caractères dans les critères de sélection pour le classement des bois et pour le phénotypage à grande échelle.

Impact of Charcoal Production on Biodiversity in Togo (West Africa)

In Togo, firewood and charcoal contribute more than 80% to the total domestic energy requirements (Kokou et al., 2009). This traditional energy represents about an annual average consumption of 419,964 tons per year on national level (Fontodji, 2007). This incessant growing request for traditional energy is ensured by national production. Unfortunately, this important consumption of charcoal had enormous consequences on the ecosystems since the methods used by the producers and the consumption modes of charcoal by households still remain archaic. Indeed, the production yield is about 15 to 20% i.e. 150 to 200 kg of wood produced per ton of woody material (Girard, 2002) and during the cooking with charcoal, the loss in energy is about 8 to 13% (Thiam, 1991). This situation is an important waste of wood causing the felling of a great number of trees. Moreover, the producers claim that the charcoal is of good quality when part of the wood used is fresh. Therefore, the excessive exploitation of the forestry resources for energy purposes puts an important pressure on the ecosystems and leads consequently to serious harmful effects on the environment and the biodiversity preservation. The objectives of this article are: (1) to analyze the impact of charcoal production on the natural ecosystems; (2) to assess the pressure on the key plant species as well as (3) on the soil physico-chemical properties soil and fauna diversity inside the kilns; (4) to assess how national environment policies and laws regulate charcoal production activities.

Environmental and wood biophysical variabilities in teak plantations in Togo (West Africa).

Abstract This survey addresses the influences of ecological factors on wood biophysical properties of teak wood in plantation in Togo. On national scale, these plantations are discriminated in six ecological groups using a correspondence factor analysis. The same analysis applied to the wood biophysical properties permits to discriminate Togolese teak in six groups also. Within these six biophysical groups, wood density ranged from 600 to 800 kg/m3. Mesurements of colour permit to classify these plantations in three categories. Natural durability of these plantations varies from highly durable to durable. At Tchorogo forest site scale, a survey using synusial approach to phytosociology permitted to describe three phytocoenoses with different productivity index which are Icacina senegalensis phytocoenose, Ressantia indica phytocoenose and Daniellia oliveri phytocoenose.

Stochastic modelling of tree architecture and biomass allocation: application to teak (Tectona grandis L. f.), a tree species with polycyclic growth and leaf neoformation

Background and aims For a given genotype, the observed variability of tree forms results from the stochasticity of meristem functioning and from changing and heterogeneous environmental factors affecting biomass formation and allocation. In response to climate change, trees adapt their architecture by adjusting growth processes such as pre- and neoformation, as well as polycyclic growth. This is the case for the teak tree. The aim of this work was to adapt the plant model, GreenLab, in order to take into consideration both these processes using existing data on this tree species. Methods This work adopted GreenLab formalism based on source-sink relationships at organ level that drive biomass production and partitioning within the whole plant over time. The stochastic aspect of phytomer production can be modelled by a Bernoulli process. The teak model was designed, parameterized and analysed using the architectural data from 2- to 5-year-old teak trees in open field stands. Key results Growth and development parameters were identified, fitting the observed compound organic series with the theoretical series, using generalized least squares methods. Phytomer distributions of growth units and branching pattern varied depending on their axis category, i.e. their physiological age. These emerging properties were in accordance with the observed growth patterns and biomass allocation dynamics during a growing season marked by a short dry season. Conclusions Annual growth patterns observed on teak, including shoot pre- and neoformation and polycyclism, were reproduced by the new version of the GreenLab model. However, further updating is discussed in order to ensure better consideration of radial variation in basic specific gravity of wood. Such upgrading of the model will enable teak ideotypes to be defined for improving wood production in terms of both volume and quality.

Useful near infrared spectroscopy model calibrations on solid wood samples of Pterocarpus erinaceus (Poir.) for physical, mechanical and colour properties

Pterocarpus erinaceus (Poir.) (local name: Toti, Tem) is a species endemic to the Guinea-Sudan and Sudan-Sahel zones. It is over-exploited for its wood, which is sold in international trade to China and Indian markets. The selection of high performance wood based on wood properties and their vegetative reproduction represents the best option for the establishment of plantations with the aim of promoting the restoration of degraded natural resources. However, measurements of these characters are lengthy, time consuming and destructive, and difficult to perform in Togo because of the lack of equipment. An alternative to those methods is near infrared (NIR) spectroscopy. The aim of this study was to assess the efficiency and feasibility of near infrared spectroscopy for predicting the physical and mechanical properties and the colour parameters of P. erinaceus wood from Burkina Faso, Niger and Togo. The properties were determined by conventional method and correlated with near infrared spectra using partial least square regression. The partial least square regression models were tested by cross-validation and by external validation. The results of this study showed the possible use of near infrared spectroscopy to estimate the physical and mechanical properties and the colour parameters of P. erinaceus wood. In fact, when validating prediction models for radial and tangential shrinkage, the fibre saturation point (FSP) showed R2 values of 0.70, 0.71, and 0.92, respectively, with ratio performance deviation values of 1.84, 1.87 and 3.57. For the colour parameters L*, a* and b*, the R2 values were 0.83, 0.74 and 0.67, respectively, with ratio performance deviation values of 2.40, 2 and 1.70. The results showed that the basic density and fibre saturation point models were classed as good to very good, respectively. Near infrared spectroscopy can therefore be used to predict efficiently the properties of P. erinaceus wood for a large number of samples, enabling the incorporation of those traits in breeding criteria.

EVALUATION DES PARAMÈTRES DE CROISSANCE DES ESSENCES FORESTIÈRES LOCALES EN PLANTATION AU TOGO : CAS DE TERMINALIA SUPERBA ENGL. & DIELS ET TERMINALIA IVORENSIS A. CHEV

Introduction: Renal failure underlies various etiologies among which are infectious and autoimmune origins which may link directly or indirectly with blood groups. Objectives: To determine the frequency of blood groups among a sample of patients with renal failure at Royal medical services, and to investigate the association of renal function tests with blood groups. Methodology: A retrospective study design was followed to collect data from files of patients with renal failure. Files of renal patients was included if blood groups were written and kidney function tests were provided. A data sheet was made for each patient that included relevant information about renal patients. A total of 197 files were reviewed. Data were entered into excel sheet to make raw data for all patients. Data analysis was conducted using SPSS V20. Data were presented as frequencies and percentages. The relationships between blood groups and renal function tests were investigated using T-independent test. Significance was considered at alpha level 0.05), except for potassium level which was observed in its maximal level among patients with blood group A, and its minimal levels were observed among patients with blood group AB (p=0.032). Conclusions: The present study showed that renal failure patients exhibited more frequency with blood groups A and O and agreed with other studies in which blood group AB is the least associated blood group with renal failure. The level of potassium was highest in patients with blood group A and lowest in patients with blood group AB and this was statistically significant (p=0.032).

CARACTÉRISTIQUES BIOPHYSIQUES DU BOIS DE PTEROCARPUS ERINACEUS (POIR.) EN ZONES GUINÉENNE ET SOUDANIENNE AU TOGO

Pterocarpus erinaceus (Poir.) is a tree species found in the Soudanian and Guinean climatic zones in Togo. It is of high socio-cultural importance because of its many uses, but little is known about the technological properties of its wood. This is why a study was conducted to determine the physical and mechanical properties (density, shrinkage, FSP, MOE, MOR, compression, hardness) of its wood in relation to environmental condi- tions. The results for the wood of 19 trees of about 18 to 60 years of age, growing in two ecological zones (Keran Park in the Sudanian zone and Abdoulaye in the Guinean zone), show that density, infra- density, compressive yield stress and anisotropic shrinkage are all higher in the Keran trees. Regarding shrinkage, FSP, MOE, tensile strength and hardness, no significant differences were found between the two sites. The expected cor- relations were found between density and hardness. The study also shows that the physical and mechanical properties of Pterocarpus erinaceus wood are virtu- ally unaffected by cambium age.