Tropical Wood Research Articles

Estimation of static bending properties, hardness and toughness of Brazilian tropical woods using mercury intrusion porosimetry analysis

Resumo ANBR 7190 (ABNT, 1997) define a caracterização simplificada, onde há o uso de relações matemáticas entre as propriedades de resistência e rigidez. Devido à grande influência da porosidade e da densidade aparente nas propriedades das madeiras e à busca por modelos matemáticos cada vez mais precisos, este trabalho teve como objetivo’ gerar modelos de regressão para a estimativa das propriedades de flexão estática (resistência “f M ” e módulo “E M ”), resistência à dureza paralela “f H,0 ” e normal às fibras “f H,90 ”, e resistência à tenacidade “W” de madeiras tropicais brasileiras a partir dos valores de porosidade, obtidos por meio da análise de porosimetria por intrusão de mercúrio, da densidade aparente e com base em ambas as propriedades em modelos de regressão multivariáveis. Todos os modelos de regressão apresentaram coeficientes de determinação “R2” superiores a 50%. A f M , a f H,90 e a W foram melhor estimadas pela densidade aparente, enquanto o E M e a f H,0 foram melhor estimados considerando a densidade aparente e a porosidade.

Management and classification of waste from the primary processing of Brazilian Amazon tropical wood for energy-generation purposes

Management and classification of waste from the primary processing of Brazilian Amazon tropical wood for energy-generation purposes

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.

Evaluation of the potentials of Jatropha curcas seed oil and in combination with leaf extracts of Cymbopogon citratus, Ocimum basilicum, and Eucalyptus globulus as wood preservatives against Macrotermes bellicosus termites

The preservation of non-durable woods such as Ayous through the use of environment friendly products is nowadays a major concern to many tropical wood researchers. The objective of this work was to assess the potentials of Jatropha curcas oil (JCO) alone and in combination with Cymbopogon citratus (JCO + CC), Ocimim basilicum (JCO + OB), and Eucalyptus globulus (JCO + EG) leaves extracts at different concentrations (1, 2, 4, 8, and 16 mg) as wood preservatives of Ayous (Triplochiton scleroxylon) against Macrotermes bellicosus termites. The extracts were tested for their toxicity and repellency on termites. Subsequently, treated and untreated wood was exposed to termites for four weeks. Termite response to treatùents varied with plant species, concentration, and exposure time. Ocimum basilicum extracts combined with J. curcas oil appeared to be the most effective against termites at 16 mg/l for in-vitro tests. It was also shown that the tested treatments were repellent to termites and therefore their mortality could not result from inhalation. J. curcas oil significantly improved the persistence of the treatments. Finally, a combined treatment of J. curcas oil and methanolic extracts of O. basilicum yielded the best protection of Ayous to termite attack, as shown by an average mass loss of 2%. Further research is needed to improve the longevity of the treatments on wood over time.

Growth and drought resilience of four native tree species suitable for reforestation of Brazil’s Atlantic Forest

Abstract Deforestation of tropical forests has been a critical issue affecting climate change mitigation and biodiversity conservation. Reforestation strives to remedy this situation, yet it is futile as long as deforestation of primary forests continues. Since deforestation is partly motivated by the demand for valuable tropical wood, reforestation should focus not only on planting native tree species, but specifically on a high diversity of native tree species with high-quality wood. However, the eco-physiological information required for growing such species is limited, and their resilience to drought events is unknown. Here, we focused on four native tropical wood tree species identified as suitable for Brazil’s Atlantic Forest reforestation. Growth, carbon assimilation, water-use and xylem hydraulics were studied in seedlings of the two legume species Dalbergia nigra and Plathymenia foliolosa and the two non-legume species Cariniana legalis and Zeyheria tuberculosa. Seedlings were monitored weekly for 9 consecutive weeks, three to five weeks of which under induced drought. Growth and carbon assimilation were 25–65 per cent higher in the legume vs. non-legume species. In turn, non-legume species mostly avoided the drought by stomatal closure, producing a 50 per cent higher water-use efficiency (WUE) compared with the legume species. The average water potential at 50 per cent stomatal conductivity (Ψgs50) for legume species was −2.6 MPa, whereas for non-legume species it was −0.85 MPa. Still, each species showed a unique set of responses, indicating different growth strategies under mesic and xeric conditions. Our results indicate a divergence among legume and non-legume species, driven by a trade-off between plant productivity (carbon assimilation and growth) and plant safety (stomatal regulation and WUE). All in all, the four species of juvenile potted plants demonstrated a high capacity for recovery from drought, which supports their potential role in future reforestation under climate change.

Tropical wood species: alternative model to determine the characteristic compressive strength perpendicular to grain

Brazil has a vast area of native forests with the potential to be sustainably exploited for application in civil construction. Density is a key factor when analysing the characteristics of different wood species and their future uses, and additionally it can be used as an estimator for other mechanical properties of wood. Furthermore, in a developing country like Brazil, carrying out various characterisation tests for different wood species is sometimes impossible because of the associated high costs. The Brazilian standard ABNT NBR 7190:1997, Design of Timber Structure, governs wood construction and timber structures in Brazil. However, this guideline lacks equations that link the majority of mechanical characteristics to density. Therefore, the main aim of this study was to propose regression models for estimating compressive strength perpendicular to grain, for 17 native species of Brazilian tropical wood, as a function of apparent density and the characteristic value of apparent density. From the results obtained, it is possible to conclude that all the regression models provided in this study were successful in estimating characteristic compressive strength perpendicular to grain (fc90,k), and that the model from Equation 3 in this work, a linear model with one independent variable, might be included in future revisions of ABNT NBR 7190:1997.

A Review of the Advances Made in Improving the Durability of Welded Wood against Water in Light of the Results of African Tropical Woods Welding

Wood plays a major role in the production of furniture and wooden structures. Nevertheless, in this process, the massive use of adhesives and plural connectors remains a definite problem for health and the environment. Therefore, wood welding is a breakthrough in this respect. This paper reviews the applications of wood welding in furniture and construction and then examines advances in improving the durability of welded wood against water. Our contribution also highlights the need to join African tropical woods using the rotational friction welding technique. According to our results, these woods present interesting chemical singularities, which could provide solutions to the water vulnerability of the welded wood. Moreover, the use of such a joining method would first free the Cameroonian furniture industry from the chemical industry, secondly position it at the forefront of new eco-design trends and thirdly make it competitive with other countries in the Central African sub-region. These works enrich the long and rich bibliography on the technique of wood welding, which has long been conspicuous by its absence of tropical woods.

Representatividade do módulo de elasticidade na compressão paralela às fibras da classe C40 no projeto de estruturas de madeira

ABSTRACT: Brazil has the world’s second largest forest area, which makes the exploitation and use of varied species in civil construction conducive. One of the traditional uses of wood is to build roofs for different purposes. Considering that the most recurrent pathologies in the roof structures are related to the excessive deformations observed in the structural elements, particularly in those subjected to bending. This study verified the effective representativeness of the stiffness value established by the Brazilian Class wood standard, C40. Batches of eight different tropical wood species were considered, whose framing occurred in the referred Class. Results obtained from the confidence intervals for each evaluated species led to the conclusion that the value of 19500 MPa for the modulus of elasticity is not representative for Class C40 because the value observed in this study was 14467 MPa, which is 26% lower than the normative reference. This observation is an initial indication that the adoption of the value of 19500 MPa by the standard is unfavorable to the safety of the structure, justifying the pathologies observed in the service performance of the roof structures.

Prediction of the basic density of tropical woods by near-infrared spectroscopy

Prediction of the basic density of tropical woods by near-infrared spectroscopy

An Evaluation of the Physicochemical, Structural and Morphological Properties of Selected Tropical Wood Species for Possible Utilization in the Wood Industry

An Evaluation of the Physicochemical, Structural and Morphological Properties of Selected Tropical Wood Species for Possible Utilization in the Wood Industry

Bamboo and value addition: a boon for industrial development

Bamboo has been increasingly used as a substitute for tropical timber in the International market. Value-added bamboo products are becoming popular due to their characteristics of durability and strength, which resemble the qualities of tropical wood while providing an equally sustainable alternative. Bamboo is considered a grass with rapid growth. As it is a colony plant, it produces new canes (culms) every year from the root system. After 3 to 5 years, culms are ready for harvest, depending on the species. Every year, 5–6 culms can be harvested (from the species that are growing in clumps). Due to this feature, bamboos are mostly used in the rural and semi-urban areas to make houses and so is known as 'poor man's timber. Bamboo shows a very significant part in day-to-day survives (lodging, service, revenue, gasoline, etc.). Lately, bamboo has also found more uses in the manufacturing areas as well as in transitory assemblies. Moreover, being a vital section of cottage and rural business, it is also utilized in some dedicated different usages such bamboo wood, bamboo based-laminates, floor tiling, strengthening in cement material etc. Pulp and paper, Gasoline (charcoal), Fixtures and Handcrafts (picnic basket, jewellery, ball-points, cycles etc.), Building (houses, channels framework, armoured, barriers, concrete, boats), Harmonious Gadgets, Customary drugs, Food (shoots, wine) and silage. Separately from the varied usages of bamboo, the tender sprouts, being little in fat, rich in dietary fibre and mineral content, decent source of potassium, calcium, manganese, zinc, chromium, copper, iron and lesser quantity of phosphorus and selenium. The sprouts are eaten due to their unusual palate, flavour, medicinal and nourishing importance. Diverse value added foodstuffs such as nuggets, pickle and biscuit can be prepared from new bamboo sprouts. Anti-carcinogenic ingredients existing in sprouts marks them a regular portion of regime. It is assumed that bamboo extract offer anti-inflammatory effects. Thus, this paper discusses about the bamboo and its value addition via bamboo-based products industry's future.

Gasification of charcoal derived from tropical wood residues in an updraft fixed bed reactor

This paper aims to produce hydrogen-rich synthesis gas from the charcoal of three tropical tree species. The approach involves sequentially the production and characterization of charcoal, the production of syngas by air gasification; and then the determination of the composition of syngas. Proximal analysis of charcoal gave ranging from 6.10 to 7.05 %; 71.51 to 77.50 %; 20.14 % to 26 % and 1.83 % to 2.48 % respectively for moisture contents, fixed carbon, volatile matter and ash contents. The gas proportions of the syngas for the three wood species do not vary significantly, with hydrogen content ranging from 20.98 % to 21.88 %, carbon monoxide (CO) from 22.2 % to 23.29 %, H2/CO ratios between 0.91 and 0.98, and the calorific value of the syngas around 6.21 MJ/Nm3. The above results show that the wood residue charcoals of the three species used in this study are suitable for the production of hydrogen-rich syngas.

WOOD PREDICTORS IN NEOTROPICAL STREAMS: ASSESSING THE EFFECTS OF REGIONAL AND LOCAL CONTROLS IN AMAZON AND CERRADO CATCHMENTS.

Large wood plays a critical role providing complex habitat structure in rivers and streams. The instream wood regime consists of wood recruitment, transport, retention, and decay in river corridors. In tropical streams, transport and decay are thought to be the dominant influences on the amount instream wood stored, and these are driven by upstream forest cover, as well as catchment hydroclimatic and geomorphic characteristics. Lack of studies of the tropical wood regime leave many uncertainties. Notably, the wood regimes in the neotropical Amazon and Cerrado biomes are not known, and rapidly changing land-use threatens efforts to understand their natural wood regime. We investigated predictors of instream wood in catchments of the Amazon and Cerrado subject to a wide range of agricultural land use to identify the critical factors controlling wood recruitment and load. Using the structural equation modelling technique, we disentangled the complex net of regional and local controls. Contrary to our expectations, local drivers, such as the relation between the piece size and channel dimensions, discharge, stream power and riparian forest were the most important predictors of instream wood. The amounts of wood found in these streams were primarily the result of the wood delivered by the local riparian forest and how much of that wood remains trapped. Therefore, the preservation of the forested riparian zones in Amazon and Cerrado streams is crucial for maintaining the sources of wood as well as the channel morphology capable of trapping and retaining instream wood. Further research should compare reference and disturbed streams to quantify the influence of anthropogenic activities on instream wood and its primary influences. This information would facilitate assessing the extent of human alteration and developing mitigating measures to arrest or reverse changes that reduce instream wood and degrade aquatic and riparian habitat in neotropical rivers and streams.

An Integrated Similarity Analysis of Anatomical and Physical Wood Properties of Tropical Species from India, Mozambique, and East Timor

Tropical species are highly valued timber sources showing a large diversity of wood characteristics. Since there are major concerns regarding the sustainability of these tropical species in many tropical regions, knowledge of the variability in wood properties is therefore a valuable tool to design targeted exploitation and to enlarge the wood resources base, namely by identifying alternatives for CITES-listed species. In this study, 98 tropical wood species belonging to 73 genera from India, Mozambique, and East Timor were investigated regarding wood anatomy and physical properties. Numerical taxonomy, by means of cluster analysis and principal component analysis grouped species with anatomical and physical similarities from different geographical origins. In addition to wood density, ray and vessel characteristics as well as wood moisture and wood shrinkage properties explained the main variability of these species. The contribution of wood color patterns was highlighted as consistently separating the Mozambique woods. A distinct geographical pattern was not observed, reinforcing that species from India, Mozambique, and East Timor show similar anatomical and physical wood properties, which could be useful to increase timber trade diversity. The multivariate analysis showed that species from Mozambique, such as Morus mesozygia, and Millettia stuhlmannii and Swartzia madagascariensis, could be alternatives for the CITES-listed species Cedrela odorata and Dalbergia melanoxylon, respectively.

Improving the efficiency of forest companies by optimizing the key indicators of sustainable forest management: a case study of the Far East

Forest plantations provide a wide range of products. Therefore, it is vital to ensure the sustainable growth and adequate management of forest resources. This study aims to examine the current challenges facing the forest industry, such as the depletion of forest resources, the increasing cost of wood processing products, and intensifying competition in the timber market (caused by the tropical wood supply). These challenges force the world’s leading forest countries to intensify forest cultivation, to consult forest industries in the Far East and to optimize the sustainable use of forest resources. It was found that current distribution of cutting practices threatens the forest ecosystem. The study suggests a scheme where 10–30% of forest area is clear-cut, 70–90% is selectively logged, and 20–35% is exposed to gradual felling. Factors, such as harvesting time, exhaust emissions, the loss of young trees, topsoil degradation, load on the soil surface, and the slope angle are essential for building mathematical models of forest sustainability. The intensity of wood transportation is also a critical factor influencing the above indicators. The study proposes a model for reorganizing regional wood harvesting companies to improve their profitability. The theoretical model is adapted to the Far Eastern context, but is suitable for use in other parts of the world.

Polystyrene-Impregnated Glulam Resistance to Subterranean Termite Attacks in a Laboratory Test.

This study aimed to enhance tropical fast-growing tree species’ resistance to subterranean termite (Coptotermes curvignathus) attacks through the manufacturing of polystyrene glued-laminated timber (glulam). Three young tropical wood species, namely manii (Maesopsis eminii), mangium (Acacia mangium), and rubber-wood (Hevea brasiliensis), were cut into laminae. After drying, the laminae were impregnated with styrene monomer, then polymerized using potassium peroxydisulfate as a catalyst and heat. The polystyrene-impregnated laminae were constructed using isocyanate glue and a cold press for three-layered glulam. Untreated or control glulam and solid wood specimens were also prepared. The specimens of each wood species and wood products (solid wood, control glulam, and polystyrene glulam) were exposed to the termite in a laboratory test according to Indonesian standards. The results showed that mangium wood had better resistance to the termite attack than manii and rubber-wood, with both of those woods performing the same. Among the wood products, the glulams were equal and had higher resistance to the termite attack than solid wood. To enhance the termite resistance of polystyrene glulam, we suggest that the polymer loading of polystyrene on each lamina should be increased. In our evaluation of the products’ order of priority, polystyrene glulam emerged as performing best towards subterranean termites attack.

Natural durability of five tropical wood species in field decay tests

Natural durability of five tropical wood species in field decay tests

Physicochemical and hygroscopic properties of charcoals produced from residues of two tropical woods from Cameroon

ABSTRACT The aim of this study was to determine the physicochemical and hygroscopic properties of charcoals from Doussie (Afzelia africana) and Okan (Cylicodiscuis gabunensis), produced from residues of two tropical woods from Cameroon. The properties determined for these charcoals included physical (moisture content, basic density, high heating value) chemical (proximate analysis, ultimate analysis, FT-IR analysis), and hygroscopic (absorption and sorption) properties. Our results show that these properties differ between the two woods. Higher values were obtained with Okan, except for the fixed carbon content. A higher diffusion coefficient on water uptake was also observed with charcoal from Okan (3.25 × 10−8 ± 0.22 m2/s) compared to charcoal from Doussie (2.42 × 10−8 ± 0.21 m2/s). The highest equilibrium moisture contents in sorption are obtained with charcoal from Okan. Our results also reveal a relationship between hygroscopic behavior and charcoals properties. It was found theoretically that an increase of initial moisture content of charcoals about 19% caused a decrease in their initial fixed carbon content about 2% and in their initial high heating value about 2.5%. The charcoals studied are of good quality and meet the recommended standards for domestic use even in humid areas.

Improved wood species identification based on multi-view imagery of the three anatomical planes

BackgroundThe identification of tropical African wood species based on microscopic imagery is a challenging problem due to the heterogeneous nature of the composition of wood combined with the vast number of candidate species. Image classification methods that rely on machine learning can facilitate this identification, provided that sufficient training material is available. Despite the fact that the three main anatomical sections contain information that is relevant for species identification, current methods only rely on transverse sections. Additionally, commonly used procedures for evaluating the performance of these methods neglect the fact that multiple images often originate from the same tree, leading to an overly optimistic estimate of the performance.ResultsWe introduce a new image dataset containing microscopic images of the three main anatomical sections of 77 Congolese wood species. A dedicated multi-view image classification method is developed and obtains an accuracy (computed using the naive but common approach) of 95%, outperforming the single-view methods by a large margin. An in-depth analysis shows that naive accuracy estimates can lead to a dramatic over-prediction, of up to 60%, of the accuracy.ConclusionsAdditional images from non-transverse sections can boost the performance of machine-learning-based wood species identification methods. Additionally, care should be taken when evaluating the performance of machine-learning-based wood species identification methods to avoid an overestimation of the performance.