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The increase in global temperature results in changes in rainfall patterns and can cause structural and functional changes in trees. Each plant is forced to face hydraulic safety limits and adopt a behavior to regulate its water status. The objective of this work was to evaluate the changes in the hydraulic architecture of the xylem of commercial eucalyptus clones in order to distinguish the hydraulic adjustments in a wide gradient of water availability. Eucalyptus urophylla (A1) and E. grandis × E. camaldulensis (C3) clones at six years old at 4 sites in Brazil distributed in a rainfall gradient and in two water conditions were analyzed: control (100% of total local rainfall) and rainfall reduction (RR). Xylem traits were evaluated at annual intervals and averaged over the entire growth period of the seven trees sampled at each site and water condition. The sites influenced the clones, with the greatest effect being the rainfall reduction treatment in C3 on the vessel wall diameter, area and thickness, double wall thickness, conduction area, vessel composition index, theoretical and potential hydraulic conductivities, vessel implosion resistance and vulnerability. The rainfall reduction provided an increase of 12% in vessel density, 8% in the double vessel wall, and 27% in theoretical hydraulic conductivity in the drought-tolerant C3 clone. The vessel wall thickness in the A1 clone was more responsive with a 3% increase in rainfall reduction, with an effect on double-wall thickness and vessel implosion resistance. Other hydraulic adjustment strategies were observed, such as the highest occurrence of tylose and a tradeoff between vessel diameter and frequency for the C3 clone. The greater variation in wood density was explained by variations in the lumen area of the xylem vessels and by vessel implosion resistance.

Micro- and nanofibrillated cellulose (MNFC) was extracted from pineapple stems by acid hydrolysis, then characterized and tested in two concentrations (0.5 and 1.0 wt%) in polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives. The modified adhesives were used to glue three tropical wood species (Vochysia ferruginea, Cordia alliodora, and Gmelina arborea), and their corresponding bond strength resistance was determined. MNFC and the correspondent adhesives were characterized by TGA, FTIR, SEM, TEM, AFM, and viscosity determination. The TGA analysis of MNFC showed three decomposition reactions. The SEM, TEM, and AFM evaluations demonstrated the presence of micro- and nanosized dimensions of particles after the acid hydrolysis of pineapple stems. Adding 1 wt% MNFC to PVAc and UF adhesives increased their thermal stability in similar manner. Viscosity diminished in both modified adhesives with MNFC; however, this reduction did not affect the adhesion properties in the tropical wood tested. MNFC added to PVAc and UF adhesives improved shear strength (SS) of the glue line in the three tropical species tested. The highest SS increase was obtained when adding 0.5 wt% MNFC to PVAc in V. ferruginea, and 1 wt% MNFC concentration in the case of C. alliodora and G. arborea. In the case of UF adhesives, the application of 1 wt% MNFC produced significant differences in SS for the three tropical species studied.

espanolEn construccion de viviendas, las estructuras mas eficientes para soportar las cargas provenientes de techumbres corresponden a las cerchas. Cuando se trata de fabricarlas con madera, un punto importante de estas son las uniones. Actualmente se ha introducido la utilizacion de placas metalicas dentadas para estas uniones, sin embargo, el mercado aun conoce poco de ellas y su posibilidad de utilizacion en casas. Por lo que, este estudio reporta un primer sondeo cualitativo por medio de una encuesta estratificada por publico objetivo, del uso de cerchas de madera con placas metalicas dentadas fabricadas con madera de plantacion en Costa Rica. Fue encontrado que el 100 % de los encuestados considera a la madera como un material viable para la construccion, por almacenar dioxido de carbono y ser un recurso renovable. Ademas, el 90 % de los encuestados, considera que la madera de las plantaciones nacionales es de buena calidad. Sin embargo, solo un 28 % prefiere la utilizacion de las cerchas como elemento estructural en techumbres y el 40 % coincide en que el uso de la placa es una buena opcion tecnologica. Segun este primer sondeo de mercado de la cercha de madera con placa metalica, el 80 % de encuestados estaria dispuesto a adquirirla; dandole un rango de precio entre ¢45 000 a ¢50 000 por cercha. EnglishIn housing construction, the most efficient structures to support the loads coming from roofs correspond to the trusses. When it comes to manufacturing them with wood, an important point of these are the joints. Currently the use of metal plates has been introduced for these unions, however, the market still knows little about them and its possibility of use in wooden houses. Therefore, this study reports a first qualitative survey by means of a survey stratified of the use of wooden trusses with metal plates fabricated with plantation wood in Costa Rica. It was found that 100 % of respondents consider wood as a viable material for construction, for storing carbon dioxide and for being a renewable resource. In addition, most consider that the wood from trees growing in plantations in Costa Rica is of good quality. However, only 28 % prefer the use of trusses as a structural element in roofs and 40 % agree that the use of the metal plate is a good technological option. According to this first market survey of the wooden truss with metal plate, 80 % of respondents would be willing to acquire it; giving it a price range between ¢ 45 000 to ¢ 50 000 per truss.

To elucidate the development of heartwood, bark, sapwood, pith and specific gravity of wood in fast-growing teak (Tectona grandis) plantations in Costa Rica, we sampled three trees in each of 55 plantations and modelled each variable with age, site and different tree heights. Age and stand density of plantations were significant correlated with stem diameter at breast height and total height of the tree. Formation of heartwood was initiated at the age of 4-year-old and increased in direct proportion with age. The age of plantation had a significant relationship with stem diameter at breast height, heartwood percentage, sapwood thickness, sapwood percentage, percentage of bark, pith diameter and percentage, and specify gravity. The model for these tree parameters was model with these parameters as dependent variable and in relation to age as independent variable.

Light (Tlight), middle (Tmiddle) and severe (Tsevere) torrefaction processes by TGA in woody biomass were evaluated in relation to devolatilization rate (Drate), maximum devolatilization rate (DRmax), temperature at the level of 50% weight loss (T50), rate of weight loss at T50 (R50) and weight loss during torrefaction (Wloss-DT). The relationship between these parameters with cellulose, lignin and extractives content was established. The TGA and devolatilization curves showed that DRmax was of 4.16, 1.80 and 0.70%/min for Tlight, Tmiddle and Tsevere respectively. Wloss-DT in Tlight ranges between 3 and 6%, between 9 and 14% in Tmiddle and from 11 to 16% in Tsevere. G. arborea showed the highest Wloss-DT, with 29.10% for Tsevere and C. Lusitania and T. grandis the lowest Wloss-DT, with 15% for Tsevere. The duration of Dmax was of 5 min in Tlight and Tmiddle and 6 min in Tsevere. Cellulose, lignin and carbon presented statistically significant correlations with R50, T50, Wloss-DT and DRmax. Ash content was correlated with Wloss-DT and DRmax in all torrefaction condition. Extractives in dichloromethane was significantly in many parameters. We conclude that the torrefaction of different woody species can be optimized as biomass feedstocks with a specific temperature and time of torrefaction.

The present work studies the morphological, physical, mechanical and chemical properties, decay resistance, preservation and workability of Cedrela odorata wood from trees growing in agroforestry systems with Theobroma cacao at four ages (4-, 5-, 6- and 7-years-old) in Costa Rica. It was found that the morphological properties (heartwood, pith and bark), together with the physical properties (specific gravity, green density, shrinkage and green moisture content) presented few differences at the four ages. The wood from 4-years-old trees was the only exception, showing less resistance in compression, flexion and lateral hardness. The content of lignin, carbon, and extractives in hot water were not affected among the different ages, contrary to the rest of chemical properties. In relation to decay resistance in accelerated tests with the fungus Trametes versicolor, the wood is classified as highly resistant, while with the fungus Lencites acuta it is classified as moderately resistant. As concerns properties related to industrialization, it was found that the wood can be preserved through vacuum-pressure methods obtaining similar results as those from other plantation timbers. As for workability tests, the wood from the 4-years-old trees show acceptable to very poor performance, differing from trees from the other ages.

Stem flattening in Rhynchosia pyramidalis (Fabaceae) is achieved by the development of crescent-shaped successive cambia on two opposite sides of the stem (referred hereafter as distal side). Other lateral sides of the stem (adjacent to supporting host and its opposite side, referred as proximal sides) usually possess single cambium. In the young stems, parenchymatous cells located outside to protophloem of distal side dedifferentiate and develop small segments of cambium. Concomitant to bidirectional differentiation of the secondary xylem and phloem, these newly developed cambial segments also extend in tangential directions. Differential activity of newly developed crescent-shaped cambial segments deposits more secondary xylem at median position as compared to their terminal ends of the stem on distal side; consequently, it pushes the cambial segment outside, thus resulting in crescent-shaped arcs of the cambia only on two opposite sides. After the production of 1–2 mm of secondary xylem, they c...

Torrefaction can increase the energy yield of biomass for better utilization in bioenergy, but chemical changes occur during the pretreatment process. Wood residues of Cupressus lusitanica, Dipteryx panamensis, Gmelina arborea, Tectona grandis, and Vochysia ferruginea were torrefied for three different time periods (8, 10, and 12 min) and three different temperatures (200, 225, and 250 °C). The mass loss, net calorific value, ash, volatiles, lignin, cellulose, extractives, and infrared spectra were evaluated. The results showed that the mass loss in torrefied biomass varied between 10% and 70%, ash content varied between 0.19 and 7.00%, and volatiles content varied between 63 and 85%. Net calorific value values varied between 17 and 23 MJ/kg, increasing with the increased torrefaction temperature. Cellulose varied between 49.85 and 67.57%. Lignin varied between 27.33 and 41.09%. The extractives varied between 3.70 and 16.86%. The change in the ratio of intensity (RI) for the bands identified using FTIR analyses showed that large changes occurred in hemicellulose components. The multivariate analysis showed that lignin, ash, extractives in hot water, volatiles, and mass loss were the variables that contributed most. The analysis of all these variables showed that torrefaction at 250 °C for 12 min presented the greatest biomass degradation. Torrefaction at 200 °C and 225 °C for 8, 10, and 12 min was optimal for thermal treatment of the biomass of these woody species.

Tree diameter and height, yield and chemical and energy properties increment throughout two different ages (1- and 2-year-old) were evaluated in Gmelina arborea trees growing in short rotation woody crops at three sites and three spacings (0.5 × 1.0, 1.0 × 1.0 and 2.0 × 1.0 m). The results showed great variation in parameters evaluated in relation to site, whereas for spacing the results were regular. Diameter, height and biomass yield increased in 2-year-old trees at all sites and spacings. The higher increments were observed in the 0.5 × 1.0 m spacing at sites 2 and 3. Biomass distribution in the different parts of 2-year-old trees showed increased biomass in the trunk and branches, and reduced biomass in leaves. The study of biomass properties showed increments in the specific gravity and reductions in the moisture content (MC) of trunk and branches, but MC of bark was regular. The increment in specific gravity and volatile contents was highest in the 0.5 × 1.0 m spacing, while MC of trunk, branches and bark, heat calorific value and ash content decreased. Carbon and nitrogen contents were irregular throughout spacing and sites. It was determined that at 2 years of age, Sites 1 and 2 presented normal behavior of Gmelina arborea in SRWC conditions, and in the Site 3 the changes produced improved the quality of biomass for energy purposes.

Tectona grandis is the second most important species for reforestation in Costa Rica, and any improvement in its industrialization process is important, especially the drying process. Lumber obtained from a plantation of 12-year-old T. grandis trees was used to evaluate three drying schedules that include integrated steaming processes to determine the combined effect of the steam-drying system on the dried lumber. The variations in the moisture content (MC) and drying rate (DR) with drying time (DT) both before and after the steaming process were modeled mathematically for boards that have a flat and quarter grain pattern. For both types of boards that were dried with and without steaming, a relationship between MC and DT was observed. There was inflexion at 40%, and two mathematical models were computed. Additionally, the relationship between DR and DT for boards with flat and quarter grain patterns was not affected by the steaming process, and an inflection point was observed at 30 h (40% MC for...

Woody biomasses from five fast-growth plantations of Costa Rica were evaluated in relation to thermal degradation characteristics and devolatilisation rate (Drate) using thermogravimetric analysis (TGA). The relationship between TGA parameters and Drate with content of cellulose, lignin and extractives were established. The results indicate that during degradation, the five woody biomass types (Cupressus lusitanica, Dipterix panamensis, Gmelina arborea, Tectona grandis and Vochysia ferruginea) show different temperatures and residual mass, as well as different Drate of the polymers conforming them, indicating that each biomass type has unique pyrolysis characteristics. The difference in these parameters is influenced by extractives content, and a little effect is presented due to lignin content, cellulose content and ash composition. A greater amount of extractives decreases the degradation temperatures of the different biomass components, although the residual mass was scarcely affected and if so, a positive correlation was presented. Extractives also affected the Drate more significantly than cellulose, lignin and macro- or micro-nutrients contents. Moreover, the Drate of cellulose was more affected by the extractives content than was Drate of hemicellulose, indicating a higher degree of association of extractives with cellulose than hemicellulose. In this concern, the higher the amount of extractives, the lower the Drate of cellulose.

The construction sector in Costa Rica produces approximately 100 kg per square meter of residues, of which wood waste comprises 30%. Utilization of these wastes is still limited, but options are being sought and biomass is one of them. The aim of this work was to evaluate the characteristics of biomass produced from wood waste from construction, its energy potential, and its appropriateness for pellet manufacturing by determining its energy, physical, and mechanical characteristics. It was found that wood waste from construction is composed of different species with densities below 0.5 g/cm3, 26% moisture content, and 10% ash content; contamination with cement and nails can reach 6%. The process of pellet manufacturing can adapt adequately to using wood waste from construction, with an efficiency or yielding of 33%. Pellets presented a calorific value of 19573 kJ/kg, a bulk density of 1.25 g/cm3, an apparent density of 700 kg/m3, a failure force in compression of 467 N, and durability of 94.28%. According to different standards, the results obtained for biomass from wood waste are within the range established for pellet quality; therefore, wood waste from construction can be used to produce pellets, despite the disadvantage of it presenting high ash content.

Resumen La gasificación es un proceso termoquímico en el que materias primas orgánicas se convierten en gases que contienen H2 y CO (gas de síntesis), los cuales pueden utilizarse para obtener productos como electricidad, combustibles y otras sustancias químicas. El proceso se encuentra influenciado por características propias del sistema donde se desarrolla la conversión térmica, las condiciones de operación y las materias primas empleadas. Se simuló un proceso de gasificación de biomasas enriquecidas con hidrocarburos en el que los gases generados son aprovechados para generación eléctrica, con tal de evaluar el uso de dichas materias primas. Se empleó un modelo de gasificación no estequiométrico, la ecuación de estado de Peng-Robinson, así como reacciones de gasificación conocidas. Se consideró un gasificador de corriente descendente trabajando con 22 kg/h de alimentación de mezcla 3:1 biomasa:hidrocarburos, 20 kg/h de aire (agente gasificante), 1 atm de presión absoluta y temperatura de gasificación de 900-1000°C. Los gases generados se componen de 27,44 % H2; 39,79 % CO; 5,73 % CH4; 0,1 % CO2 y 27,01 % N2. La potencia neta del gasificador es 27,82 kW y el consumo de la mezcla 3:1 biomasa:hidrocarburos 0,79 kg/kWh. La adición de hidrocarburos a biomasa mejora las características del gas de síntesis obtenido y disminuye los requerimientos de materia prima para el funcionamiento del gasificador. La mezcla 3:1 biomasa:hidrocarburos es adecuada para el desempeño del proceso, permitiendo aprovechar residuos que de otra manera tendrían que ser dispuestos y tratados, generando beneficios energéticos, ambientales y económicos. Abstract Gasification is a thermochemical process in which organic raw materials are converted into gases containing H2 and CO (syngas), which can be used to obtain products such as electricity, fuels and other chemicals. It is influenced by characteristics of the system where the thermal conversion takes place, the operating conditions and the raw materials used. It was simulated a process of gasification of hydrocarbons-enriched biomass in which the gases generated are used for electricity generation, to evaluate the use of such raw materials. A non-stoichiometric gasification model, the Peng-Robinson equation of state as well as known gasification reactions were used. A downdraft gasifier was considered working with 22 kg/h of mix feed 3:1 biomass: hydrocarbons, 20 kg/h of air (gasifying agent), 1 atm of absolute pressure and gasification temperature of 900-1000 °C. The gases generated are composed of 27.44 % H2, 39.79 % CO, 5.73 % CH4, 0.1 % CO2 and 27.01 % N2. The net power of the gasifier is 27.82 kW and the consumption of the mixture 3:1 biomass:hydrocarbons 0.79 kg/kWh. The addition of hydrocarbons to biomass improves the characteristics of the syngas obtained and reduces the raw material requirements for the operation of the gasifier. The mixture 3:1 biomass:hydrocarbons is adequate for the performance of the process, allowing to take advantage of wastes that otherwise would have to be disposed of and treated, generating energy, environmental and economic benefits.

Mortality, diameter at 30 cm over ground level, height, biomass production, and carbon capture (CC) for different tree components (trunk, bark, branches, and leaves) in two locations in Costa Rica, during their first three years and with three plantation spacings (1.0 &times, 0.5 m, 1.0 &times, 1.0 m, and 1.0 &times, 2.0 m) were obtained for Gmelina arborea Roxb. trees growing in short rotation coppice systems (SRC). In addition, regression models were developed to predict biomass production and CC using location, age, spacing, and their interactions. Biomass production was measured by weight of trees without considering dendrometric variables. Results showed that mortality was lower than 15% for one location, with probable high fertility, and almost 85% for the other location. Diameter and height of trees increased with plantation age in both locations. The highest biomass production and CC were observed in the spacings of 1.0 &times, 0.5 m2 and 1.0 &times, 1.0 m2, with 20 Mg/ha/year and 8 Mg/ha/year, respectively. The models to predict biomass production in trunk with bark, branches, leaves, total biomass without leaves, and CC in trunk, branch, and total biomass were developed using this equation: Y = &beta, 1 + &beta, 2 (location &times, age) + &beta, 3 (age) + &beta, 4 (spacing). The R2 values varied from 0.66 to 0.84, with error from 0.88 to 10.75 and indicators of goodness of fit from 60 to 83%.

In countries like Costa Rica, there is an interest in developing wooden trusses in a versatile and light way. However, there is a key aspect in the behavior of truss connections in this product. Therefore, the present study determines the structural behavior of the truss connections and the displacement, the resistance, the stiffness values and the failure mode of truss connections made with Gmelina arborea and Tectona grandis timber for angles of 0° and 90°; and three types of truss connectors (metal plates, screws and nails), subject to tension and compression loads. The results showed that metal plates show the highest load values with respect to the nails and screws in both species. Likewise, in the design and critical displacement stress, metal plates surpass the nails and screws in both species; and in the two angles. From these stress values, we proposed a model for the prediction of the stiffness for the truss connections of the intermediate angles (30°, 45° and 60°) and the test showed that the prediction was low, the bias was 3%.

A composite between particles obtained residual pallets of Pinus sp and cement was manufactured. Also, three methods were performance for wood particles: hot water washed, unwashed and unwashed with calcium carbonate (CaCO3). Different concrete-wood particle ratios were tested. Curing time was evaluated with ultrasonic pulse velocity (USV) and density of composites. Water absorption, module of rupture (MOR) in flexion, abrasion strength and resistance to decay by fungi attack were too determined. Results showed that using USV and density, curing occurs within 8 days. Moisture absorption ranges15 and 22% and decreases with decreasing of the amount of particles. MOR ranged from 0.40 a 1.23 MPa and the blocks with unwashed wooden particles and with CaCO3 addition had the greatest significant differences. In abrasion strength, blocks with unwashed wooden particles reported the best results. Finally, it was concluded that mixture with proportion of 60:40 (concrete:wood) and CaCO3 had the best performance and were not attacked by fungi decay.

Studies related to biomass production, with a focus on energy uses for short-rotation woody crops (SRWCs), are limited in Latin America. The research that is available relates to a variety of tested SRWC species (50 species), however, the most important species are Populus, Salix, Eucalyptus, Acacia, and Gmelina arborea. In the existing studies, stocking densities varied from 1111 to 20,000 trees per hectare, with square or rectangular spacing. One important advantage of SRWC systems in this region, compared to most regions worldwide, is the predictability of biomass yields due to the tropical climate conditions of the majority of the Latin American countries. Rotations of three and four years can be projected to produce total biomass yields of 30⁻50 tons/ha, with increments of 10⁻20 tons/ha/yr. Fertilization is performed in SRWC with the aim of preventing soil degradation and maintaining further production. In regards to possible uses of biofuel generated from SRWC in Latin America, an inconvenience is that there are neither well-established harvesting systems nor conventional pre-treatments to process the biomass. Processes that are available in the region that use biomass from SRWC for energy production are gasification and pellet production. Other potential biofuel processes, such as torrefaction and biochemical conversion, are limited in this area.

The main objective of this research was to evaluate the use of unmanned aerial vehicles (UAVs) in estimating the aboveground biomass and carbon, and the dasometric characteristics at three different spacings (2.5 m × 1.0 m, 2.5 m × 2.0 m and 2.5 m × 3.0 m) in a silvopastoral system (SPS) for the biomass production of Tectona grandis. A total of 90 trees were sampled, 63 of which were used to perform a dasometric evaluation (vertical and horizontal) in a spacing test in an SPS, and the rest to evaluate the use of UAVs in estimating the aboveground biomass in the spacing test. The results showed significant differences in average diameter at breast height (dbh) between spacings, and in aboveground biomass per tree. The amount of aboveground biomass and carbon per hectare increases at smaller spacings, but the differences were not statistically significant. A logarithmic model was prepared to estimate the dbh based on the crown diameter from the data collected taken in the field, since estimating this variable by means of UAVs is difficult. Significant differences were found in the aboveground biomass estimated using the field data compared to UAV data. The estimation of the crown diameter of the selected trees, hindered by the canopy closure in the SPS, was not adequate, which could influence the amount of aboveground biomass estimated using UAV data.

La torrefaccion y peletizacion se han estudiado en la generacion de calor a partir de residuos lignocelulosicos, para incrementar las propiedades energeticas del material. El objetivo del presente trabajo fue torrefaccionar aserrin de Gmelina arborea y Dipteryx panamensis a 200 °C en tres tiempos: 0, 15 y 20 minutos. Con las biomasas obtenidas se fabricaron pellets de 6 mm de diametro y se evaluaron sus propiedades fisicas, el poder calorico, la densidad y la propiedad mecanica de resistencia a la compresion. Ambas especies presentaron caracteristicas fisicas similares con respecto al diametro (0.50 mm), longitud (21.50 mm) y porcentaje de absorcion de agua (6.00 %). El poder calorico aumento de 9,749 kJ·kg-1 en la biomasa sin torrefaccionar a 18,126 kJ·kg-1 en la biomasa torrefaccionada. Los pellets de D. panamesis presentaron mayor densidad y resistencia a la compresion que los de G. arborea . Con base en los resultados, la resistencia a la compresion del pellet disminuye cuando el tiempo de torrefaccion aumenta. Existe correlacion positiva entre la densidad de los pellets y la resistencia a la compresion. La especie D. panamensis presenta mejor comportamiento a la torrefaccion y peletizacion que la madera de G. arborea .

Las curvas laminadas fabricadas con chapas vaporizadas permiten obtener radios de curvatura más pequeños que cuando no se aplica este proceso. En este estudio, se presentan el comportamiento de madera de Alnus acuminata, Tectona grandis, Gmelina arborea, Terminalia oblonga, Alnus acuminata y Swietenia macrophylla provenientes de plantaciones de rápido crecimiento en la fabricación de curvaturas con radios de (4, 6, 8, 10, 12 y 14) cm. Fue posible obtener radios de curvaturas de 4 cm, a excepción de T. grandis de donde solo fue posible obtener radio de 6 cm. El proceso de vaporizado aumentó el contenido de humedad de la chapa en un rango de 3.3% a 10.2%. El adhesivo permite que el radio de la curva fabricada se mantenga en radios menores a 10 cm y en radios de 12 cm y 14 cm la curva tiende a abrirse (máximo 1%), para todas las especies, no obstante, la abertura se estabiliza al día 4 luego de fabricada. Las delaminaciones de las chapas se producen principalmente en los radios de 4 cm a 8 cm y se presentan con mayor incidente en la T. grandis y T. oblonga. La resistencia en cizallamiento de 7,5 MPa-11,2 MPa y no se alteró al someter a pruebas de envejecimiento, pero hay una mayor delaminación en todas las especies.

Modifications to a pellet manufacturing process must be made based on the characteristics of raw material used. The purpose of this work was to determine the alternations required to a wood pellet manufacturing process and the quality of the pellets produced using this process from five energy crops. Quality measurements include: the caloric value, the loss of moisture content in each production stage, the efficiency index of particle-pellet, ash content and quality as defined using the quantity of cracks and the transversal density and longitudinal density determined using X-ray radiography. The crops analyzed were rhizomatous plants, with caloric values ranging between 17.1 and 20.3 MJ kg −1 . This work determined that it was possible to produce pellets with Gynerium sagittatum and Phyllostachys aurea using the same production process for wood; however, Arundo donax and Pennisetum purpureum needed pre-air-drying and the Sorghum bicolor required mechanical dewatering before drying. A. donax , P. purpureum and G. sagittatum provided the highest efficiency index. When evaluating the pellet quality P. aurea and G. sagittatum hard a large quantity of cracks, unlike A. donax , P. purpureum and S. bicolor . The transversal and longitudinal pellet density varied from 1129 to 1294 kg m −3 . The highest values of bulk density were obtained in A. donax and P. purpureum , followed by G. sagittatum and P. aurea , and the lowest bulk density was obtained in S. bicolor . Althogh out, some species produced cracks and high ash content, this work demonstrated that it is possible to produce pellets with moderate quality.

Resumen En un proceso de gasificación la geometría de la biomasa es un factor necesario que considerar. El tamaño, forma y densidad de las partículas del biocombustible influyen en el transporte de las especies del sistema de reacción, velocidades de secado y descomposición térmica; los cuales son factores relacionados al desempeño general del proceso. Este trabajo evaluó las diferencias significativas que existen en el rendimiento y eficiencia del sistema de generación de energía eléctrica y térmica por la incidencia de dos geometrías en la biomasa de alimentación (pellets y astillas de madera), en el desempeño de un gasificador tipo “downdraft”. El perfil de temperatura de la zona de pirólisis fue en promedio (147 ± 15) °C mayor al utilizar astillas como alimentación en comparación con el uso de pellets. La caída de presión dentro del reactor fue menor en promedio, así como su variabilidad en el sistema, al utilizar astillas como alimentación; esto a pesar de que el poder calorífico del gas de síntesis obtenido fue levemente mayor para pellets (8,00 MJ/Nm3) que con respecto al obtenido con astillas (6,18 MJ/Nm3). Se obtuvo una Eficiencia de Gas Frío, así como la Eficiencia Térmica Global mayor al utilizar astillas de madera. La capacidad de aprovechamiento de la energía del syngas para producir potencia eléctrica, medido como la Eficiencia del Motor/Generador, estuvo dentro de los valores típicos para este sistema de conversión, y fue de (21,41 ± 3,23) % para astillas y (18,94 ± 3,68) % para pellets. Se obtuvo 564,50 kWh/t de rendimiento de proceso en términos eléctricos al emplear astillas, el cual fue mayor que al utilizar pellets (487,35 kWh/t), esto a una potencia de 6,2 kW. Con respecto al rendimiento de producción de gas de síntesis, con pellets fue menor con respecto a las astillas de madera (i.e. en promedio se produjo 1,75 kg de gas de síntesis por kilogramo de astillas, lo que significa un 25 % más que con pellets de madera). En conclusión, a pesar de que el manejo de astillas de maderas requiere ciertos cuidados para evitar el atascamiento dentro del sistema de conversión “downdraft” para producir gas combustible, en general las ventajas en proceso y eficiencias son mayores al utilizar madera en forma de astillas en comparación con pellets. Abstract The size, geometry, density and mechanical properties of the biofuel particles are important factors in the performance of any biomass gasification process. They influence the mass transfer rates of the reacting species just as the drying and the thermal decomposition rates in the rest of the system. This work evaluates the significant differences between two different feedstocks, wood pellets and woodchips, on the performance and efficiency of a pilot scale “downdraft” gasifier unit with a combined heat and power system. When using woodchips as feedstock, on average, the temperature profile of the pyrolysis zone was 147 ± 15 °C higher, while the pressure drop inside the reactor and its variability were lower. The Cold Gas Efficiency and Global Thermal Efficiency of the system were higher as well with the woodchips as feedstock, despite the fact that the calorific value of the synthesis gas produced from the wood pellets was 8.00 MJ/Nm3 and the one obtained from the woodchips was slightly lower at 6.18 MJ/Nm3. At a power generation of 6.2 kW, the syngas and electrical energy yields, were also higher on average for the woodchips at 1.75 kg/kg and 564.50 kWh/t, compared to the wood pellets as feedstock at 1.40 kg/kg and 487.35 kWh/t respectively. The relationship between the electrical energy yield and the calorific value of the syngas flow was stablished by means of the Motor/Generator Efficiency, and it was within typical range for this type conversion systems, at 21.41 ± 3.23 % for the woodchips and 18.94 ± 3.68 % for wood pellets. In conclusion, even though the transport of the woodchips within system is more prone to clogging, the higher efficiency and better overall process performance obtained when using woodchips, makes it the preferred feedstock for the system compared to the wood pellets.

Aim of study: Plantations are threatened by an emerging disease called “Gmelina death disease”. The objective of this study was measured the incidence and severity of this disease and were correlated with the characteristics of the plantations, micro- and macronutrients in the soil and climatic parameters.Area of study: The present study evaluated 16 symptomatic fast-growth plantations of different age in Costa RicaMaterial and methods: Fungi were identified from xylem of infected trees. Incidence and severity was measured and correlated with the characteristics of the plantations, micro- and macronutrients in the soil and climatic parameters. Root condition and the quality (specify gravity, mechanical and decay resistance and chemical compositions), of the wood of symptomatic and asymptomatic trees were compared.Main results: Three fungal species (Chaetomella raphigera, Fusarium solani and Rhizomucor variabilis) were identified from diseased samples. Clay content in the soil profile from 10-20 cm deep explained a significant proportion of the variation in the incidence and severity of the disease, and stand density was related to severity. Although two climatic variables, Holdridge’s potential annual evapotranspiration and Thornthwaite’s potential evapotranspiration, showed a relationship between the incidence in the trees and symptoms of the disease. Infected wood turned black in symptomatic trees. Specify gravity and mechanical resistance of infected wood decreased, whereas its natural durability was unaffected. Changes were observed in the quantities of Mg, Fe, Ca, K and Zn in infected wood.Research highlights: Gmelina plantations established in sites with high stand densities and high contents of clay increase susceptibility to this disease.

This study evaluated the effect of thermo-treatment (THT) at 4 temperatures on the density, shrinking, mass loss, moisture absorption, color, durability in terms of resistance to decay, flexural strength, tensile adhesion of glue line and the infrared spectrum of the wood of Tectona grandis and Gmelina arborea. Sapwood, heartwood and radial and tangential grain patterns were studied. The results showed that the THT temperature decreases the density, the percentage of moisture absorption, the modulus of elasticity and modulus of rupture in the flexure test and the tensile adhesion of glue line. The percentage of shrinking and durability presented irregular behavior relative to the THT temperature. The percentage of mass loss increased with increasing THT temperature in both species. The total color change (∆E*) of thermo-treated wood (THTwood) also increased with increasing THT temperature. Sapwood of T. grandis and G. arborea, having clearer shades, showed a more noticeable color change compared to hardwood; however, no significant differences were obtained between some of the THT temperatures.DOI: http://dx.doi.org/10.5755/j01.ms.24.1.17545

The object of this research is to develop a model for the calibration of prefabricated timber wall frames (PTWFs) with dimension of 244 by 244 cm (width by height) respectively made of Gmelina arborea Roxb. and Hieronyma alchorneoides Allemão wood and two types of fastener (nails and screws). The PTWFs were submitted to a lateral load test and the vertical and horizontal displacement, maximum load (Pm), strength, stiffness values and mode of failure were determined. Results showed a greater failure percentage in the joint between the central stud and the top and bottom plates for both species and both fastener types used. PTWFs made of H. alchorneoides timber using screws showed greatervalues than PTWFs made of G. arborea for load at the proportionality limit and maximum load. Finally, computational model showed that the highest calibration percentage was achieved in the vertical orientation in PTWFs made using nails in both species. Meanwhile, PTWFs using screws showed calibration percentages of 58.0 and 43.5 %. The highest calibration percentage of 89.9 % was recorded in G. arborea PTWFs joined with nails, whereas the lowest calibration percentage of 69.4 % was recorded in H. alchorneoides PTWFs joined with screws., Cilj istraživanja bio je razviti model za kalibraciju montažnih drvenih zidnih okvira (PTWF) dimenzija 244 × 244 cm (širina × visina) izrađenih od drva Gmelina arborea Roxb. i Hieronyma alchorneoides Allemão te uz upotrebu dviju vrsta vezivnih elemenata (čavala i vijaka). PTWF-ovi su podvrgnuti testu bočnog opterećenja te su utvrđeni vertikalni i horizontalni pomak, maksimalno opterećenje (Pm), čvrstoća, krutost i način oštećenja. Rezultati su pokazali najveći postotak oštećenja u spoju između središnjeg nosača i gornjega odnosno donjeg okvira za PTWF-ove od obiju vrsta drva i spojenih obama tipovima vezivnih elemenata. PTWF-ovi izrađeni od drva H. alchorneoides i spojeni vijcima imali su veće vrijednosti opterećenja na granici proporcionalnosti i maksimalnog opterećenja od PTWF-ova proizvedenih od drva G. arborea. Konačno, računalni je model pokazao da je najveći postotak kalibracije postignut u vertikalnom smjeru u PTWF-ova izrađenih od obiju vrsta drva i spojenih čavlima. Istodobno, PTWF-ovi spojeni vijcima pokazali su postotke kalibracije 58,0 i 43,5 %. Najveći postotak kalibracije bio je 89,9 %, a zabilježen je u PTWF-u od drva G. arborea i spojenom čavlima, dok je najniži postotak kalibracije ustanovljen u PTWF-u od drva H. alchorneoides spojenom vijcima, a iznosio je 69,4 %.

The use of the X-ray technique and the X-ray densitometry to determine pellet particle distribution and to understand the biomass compaction and its effects in pellet properties has been limited. The present work evaluates the quality of pellets manufactured with several lignocellulosic materials by using X-ray photography for studying surface cracks and irregularities, and by using X-ray densitometry to evaluate density and its variation in longitudinal and transversal directions. Density values and their variation were correlated to the pellets' mechanical properties (mechanical durability and compression resistance). It was found that X-ray photography may be applied to evaluate the presence of cracks and irregularities in the pellets' surface; however, these are not indicators of pellet durability or compression resistance. Moreover, density evaluation by the X-ray densitometry technique allowed the determination of the pellets' mechanical resistance and durability. A negative correlation was observed between the force at break and the coefficient of variation of density. No correlation was found between the mechanical durability and the average density or its variation. According to the above results, X-ray technique can be utilized to study the pellet quality.

The purpose of the biomass torrefaction and pelletizing processes is to increase its energy properties, be environmentally friendly, decrease shipping costs, and make handling easier. The objective of the present work is to evaluate the density, internal density variation by X-ray densitometry, moisture content, water absorption, and compression force of torrefied biomass pellets of five wood species (Cupressus lusitanica, Dipterix panamensis, Gmelina arborea, Tectona grandis, and Vochysia ferruginea) under three torrefaction temperature conditions (light, middle, and severe) and three torrefaction times (8, 10, and 12 min). The results showed that the bulk density of the pellets was 0.90–1.30 g/cm3. The density variation of the pellets was higher with torrefaction at 250 °C. The moisture content decreased with increasing torrefaction temperature from 3% to 1%. Water absorption was lower in the pellets torrefied at 250 °C. The compression force was lower in the pellets torrefied at 250 °C with approximate loads of 700 N. Based on the above results, it was concluded that pellets made with biomass torrefied at 200 °C have better energy properties and evaluated properties. According to these results, pellets fabricated with the torrefied biomass of tropical species can be used in stove, gas, and hydrogen production because the pellet presents adequate characteristics.

The carbon content and the specific gravity of wood are indirect indicators of carbon storage capacity of trees. We monitored carbon content in four tropical species (Apeiba tibourbou, Guatteria amplifolia, Hyeronima alchorneoides and Tetrathylacium macrophyllum) in four different succession stages (5-15 years, 15-30 years, 30-50 years and old-growth forest of approximately 80 years old) in humid lowland forests in Costa Rica's Osa Peninsula. Carbon content varied significantly, from 0.41 to 0.51, across species and across successional stages, but it was not affected by diameter at breast height in any species. Mean wood specific gravity varied 3-fold across species, from 0.18 (A. amplifolia) to 0.54 (H. alchorneoides), whereas carbon content ranged from 0.40 (A. amplifolia) to 0.51 (H. alchorneoides). Specific gravity varied significantly (from 0.41 to 0.55) across successional stages only in G. amplifolia, whereas carbon content was different in some successional stages in A. tibourbou, H. alchorneoides and T. macrophyllum. Specific gravity and carbon content were correlated only in T. macrophyllum. Finally, results suggest that carbon content pertains to each species and it is affected by the succession stage., El contenido de carbono y el peso específico básico de la madera son indicadores indirectos de la capacidad de almacenamiento de carbono de los árboles. La variación del contenido de carbono se monitoreó en cuatro especies tropicales (Apeiba tibourbou, Guatteria amplifolia, Hyeronima alchorneoides y Tetrathylacium macrophyllum) en cuatro estados sucesionales (5-15 años, 15-30 años, 30-50 años y bosque primario, de aproximadamente 80 años) de un bosque húmedo de la Península de Osa en Costa Rica. El contenido de carbono varió significativamente, de 0,41 a 0,51, en tres especies estudiadas y los estadios sucesionales, pero este no fue afectado por el diámetro a la altura del pecho en ninguna especie. El promedio de peso específico básico varió en las diferentes especies, de 0,18 (A. amplifolia) a 0,54 (H. alchorneoides), mientras que el contenido de carbono varío de 0,40 (A. amplifolia) a 0,51 (H. alchorneoides). El peso específico básico varió significativamente (de 0,41 a 0,55) en los diferentes estadios sucesionales solamente en G. amplifolia, mientras que el contenido de carbono fue diferente en algunos estadios sucesionales de A. tibourbou, H. alchorneoides y T. macrophyllum. El peso específico básico y el contenido de carbono fueron correlacionados solamente en T. macrophyllum. Finalmente, de los anteriores resultados sugieren que los patrones de variación son propios de cada especie y estos son afectados por los diferentes estadios sucesionales.

This study details information about physical, chemical and mechanical properties, drying, preservation and workability of wood from Cordia alliodora, Dipteryx panamensis, Enterolobium cyclocarpum, Hieronyma alchorneoides, Samanea saman and Vochysia ferruginea trees, growing in forest plantations in Costa Rica. Variation of the general properties in relation to height showed that heartwood percentage decreases, bark percentage increases and pith percentage is not affected. Dipteryx panamensis showed both the highest values for specific gravity and the highest mechanic resistance. Both chemical properties and extractives presence were different among species. Heartwood was not possible to preserve in any of the species, though sapwood was. Penetration varied from partial irregular or vascular in the species. The highest durability was for Hieronyma alchorneoides and Vochysia ferruginea, species classified as of high durability. Finally, all species had good performance in the workability tests. The previous results indicate that these species, used for trading reforestation in Costa Rica, have acceptable characteristics to be commercialized and used in wooden products., El presente estudio detalla información de las propiedades físicas, químicas, mecánicas, de secado, preservación y trabajabilidad de la madera de Cordia alliodora, Dipteryx panamensis, Enterolobium cyclocarpum, Hieronyma alchorneoides, Samanea saman y Vochysia ferruginea proveniente de plantaciones forestales en Costa Rica. La variación de las propiedades con respecto a la altura mostró que el porcentaje de duramen disminuyó, el porcentaje de corteza aumentó y el porcentaje de médula no se vio afectado por la altura del árbol. Dipteryx panamensis presentó los valores de peso específico más altos, por lo tanto, también presentó los valores de resistencia mecánica más altos. No fue posible preservar el duramen en ninguna especie, pero la albura sí y su penetración varió de parcial irregular o vascular en las especies. La mayor durabilidad se presentó en Hieronyma alchorneoides y Vochysia ferruginea, especies clasificadas como de alta durabilidad. Finalmente, todas las especies presentaron buen comportamiento en las pruebas de trabajabilidad. Los resultados anteriores indican que estas especies, utilizadas en la reforestación comercial de Costa Rica, poseen características aceptables para ser utilizadas en la comercialización y uso en productos de madera.

Bent trees have been observed during the early years in juvenile plantations (less than 5 years-old) of Tectona grandis in Costa Rica. The relationship between bending and the morphological characteristics of the trees was explored. An evaluation of bent trees was conducted in six juvenile plantations (8, 17, 27, 28, 31, and 54 months old) of Tectona grandis. Site 1 with 8-month-old plantations did not display any relationship with any tree morphological variable (diameter, height, and crown weight of tree), whereas for the sites 2, 3, and 4 with 17-, 27-, and 28-month-old plantations, respectively, all the tree morphological variables were statistically correlated with the bent trees. A multiple regression analysis showed that the most influential variables were height to crown base, crown weight, diameter, and total height of the tree. An evaluation of the bending risk factor (RF) was correlated with the height to crown base, crown weight, and form factor. The modulus of elasticity and chemical compositions of bent trees differed from those of straight trees. The causes of tree bending are complex, involving, among other factors, the morphology of the trees, plantation conditions, and other factors specific to the xylem, such as the specific gravity, modulus of elasticity, and presence of calcium and magnesium in the wood.

Bent trees have been observed during the early years in juvenile plantations (less than 5 years-old) of Tectona grandis in Costa Rica. The relationship between bending and the morphological characteristics of the trees was explored. An evaluation of bent trees was conducted in six juvenile plantations (8, 17, 27, 28, 31, and 54 months old) of Tectona grandis. Site 1 with 8-month-old plantations did not display any relationship with any tree morphological variable (diameter, height, and crown weight of tree), whereas for the sites 2, 3, and 4 with 17-, 27-, and 28-month-old plantations, respectively, all the tree morphological variables were statistically correlated with the bent trees. A multiple regression analysis showed that the most influential variables were height to crown base, crown weight, diameter, and total height of the tree. An evaluation of the bending risk factor (RF) was correlated with the height to crown base, crown weight, and form factor. The modulus of elasticity and chemical compositions of bent trees differed from those of straight trees. The causes of tree bending are complex, involving, among other factors, the morphology of the trees, plantation conditions, and other factors specific to the xylem, such as the specific gravity, modulus of elasticity, and presence of calcium and magnesium in the wood.

Anatomía del tallo y desarrollo del floema interxilar en Strychnos bredemeyeri (Loganiaceae) En Strychnos bredemeyeri, pequeñas porciones de cambium dejan temporalmente de producir xilema secundario y produce más floema centrífugamente. Un nuevo segmento del cambium se diferencia en la parte exterior de este floema formado, entonces estos se unen al cilindro regular para formar un anillo. Esta repetida actividad da como resultado la inclusión de islas de floema dentro del xilema secundario, llamado floema interxilar. Luego aparecen nuevos elementos del floema asociado al cambium y a las islas de floema que aplastan los elementos no conductores de islas de floema. Junto al floema interxilar, el floema intraxilar está formado por la adición desde las células marginales de la médula. Posteriormente, pequeños arcos del cambium interno se inician en el borde interno del protoxilema en tallos gruesos. Abstract: In Strychnos bredemeyeri small segments of the cambium cease to produce secondary xylem temporarily and produce more phloem centrifugally. A new segment of the cambium differentiates outside to this phloem, which unite with the regular cylinder to form a complete ring by leaving the cambium segment in the furrow. Such repeated activity of cambium results in inclusion of phloem islands within the secondary xylem, called interxylary phloem. New phloem elements added by the cambium associated with phloem islands crush the non-conducting sieve elements in older phloem islands. Beside interxylary phloem, intraxylary phloem is added from the marginal pith cells. Subsequently, small arcs of the internal cambium initiate on the inner margin of the protoxylem in thick stems.

This study evaluated wood color change (ΔE*) and the surface quality in 10 tropical wood species painted with three finishes (composed of wax and polyurethane). Two weathering conditions were tested: natural weathering (NW) and artificial weathering (AW). The results showed that the application of these finishes, decreased the luminosity (L*), increased the redness (a*) and the yellowness (b*) parameters in all species. ΔE*, after weathering exposure, was affected significantly by L*, a*, and b, whereas for finished or pretreated wood, L* and b* are the main parameters affecting ΔE* in the 10 tropical species studied. ΔE* values found in different finishes and pretreatments are cataloged as total change of color. Other important results were that tropical light colored timber with natural pretreatment produced higher ΔE* than dark colored timber. The stains and fungal development were observed in polyurethane finishes in NW, but not in AW. The irregular and mosaic flaws were not observed in any ki...

Lignocellulosic wastes resulting from agricultural activities as well as Tetra Pak residues from urban centres can cause significant levels of pollution. A possible action to minimize this problem is to use them in the production of particleboards. The purpose of this study was to evaluate the physical, mechanical, and hydration properties of particleboards manufactured with the mixture of woody biomass (Cupressus lusitanica, Gmelina arborea, and Tectona grandis) and either agricultural wastes [pineapple leaves (Ananas comosus) and palm residues (Elaeis guineensis)] or Tetra Pak residues (TP). The results show that the particleboards prepared with TP and woody biomass can reduce the swelling and water absorption in up to 40% and 50% compared with particleboards without TP. Also, these particleboards had increased flexure resistance and shear stress (up to 100%) compared with those without TP. On the contrary, particleboards prepared with pineapple leaves in combination with woody biomass showed the lowest mechanical properties, particularly for tensile strength, hardness, glue-line shear, and nail and screw evaluation. Los desechos lignocelulósicos resultantes de las actividades agrícolas, así como los residuos de Tetra Pak de los centros urbanos pueden causar niveles significativos de contaminación. Una posible acción para minimizar este problema es usarlos en la producción de tableros de partículas. El propósito de este estudio fue evaluar las propiedades físicas, mecánicas y de hidratación de tableros de partículas fabricados con la mezcla de biomasa leñosa (Cupressus lusitanica, Gmelina arborea y Tectona grandis) y residuos agrícolas [hojas de piña (Ananas comosus) y residuos de palma (Elaeis guineensis)] o residuos de Tetra Pak (TP). Los resultados muestran que los tableros de partículas preparados con TP y biomasa leñosa pueden reducir la hinchazón y la absorción de agua hasta en un 40% y 50% en comparación con los tableros de partículas sin TP. Además, estos tableros de partículas tenían una mayor resistencia a la flexión y al esfuerzo cortante (hasta 100%) en comparación con aquellos sin TP. Por el contrario, los tableros de partículas preparados con hojas de piña en combinación con biomasa leñosa mostraron las propiedades mecánicas más bajas, particularmente para la resistencia a la tracción, la dureza, el corte de la línea de pegamento y la evaluación de clavos y tornillos. Universidad Nacional, Costa Rica Escuela de Química

Teak (Tectona grandis L. f) has been introduced to reforestation programs in many tropical countries for timber production. The use of teak plantations has changed the supply from large-diameter logs to small-diameter logs featuring a higher proportion of juvenile wood and more knots. Generally, the teak from fast-growth plantation is harvested after 15–30 years of growth, with logs ranging from 12 to 30 cm in diameter. The goal of this work was to review the factors that influence the heartwood formation, variation, quality, color, and durability in teak and to understand which factors should be controlled in fast-growth plantations. Important factors in the heartwood properties of teak trees from fast-growth plantations are as follows: the tree age, longitudinal variation, geographic location, environmental conditions, and silvicultural activities. These factors influence heartwood extractive content, color variation, and durability.

Tectona grandis and Gmelina arborea are common in commercial reforestation in the tropics. However, color variations, moisture content, and drying defects are also present in dried lumber. Moisture content variations, drying defects, and color changes were evaluated in the present work for three drying methods (kiln, solar, and air drying) during three seasons (dry, rainy, and transition season) in Costa Rica. According to the results, kiln drying had the fastest drying times, regardless of the season. On the other hand, air drying had slower drying time and higher final moisture content. With regard to defects, kiln drying produced the highest number and magnitude of defects in both species, whereas air drying showed the lowest quantity and severity of defects. No variations due to the drying methods or the season were observed in check and split, though solar drying presented intermediate values in all drying defects. The seasons of the year did not present any effect on drying defects. Finally, T. gran...

The search for efficient and versatile structural elements, leads to the fabrication of I-joists (6.5 cm × 18.5 cm × 600 cm (width × depth × length) with glue-laminated bamboo (Guada angustifolia) in the flanges and Gmelina arborea 12-mm structural plywood in the web. The results showed a modulus of rupture (MOR) of 39.45 MPa and an effective modulus of elasticity (MOE) of 17.05 GPa. Shearing in the glue line was 5.95 MPa and the lamination strength was 6.45 MPa. Structural design values averaged 9.43 MPa for bending and 4.72 MPa in shear according to Costa Rican structural standards. Both resistance value (flexure and shear) were considered satisfactory for structural proposes and I-joists fabricated with bamboo and G. arborea plywood are comparable with the Andean classification group “C” structural grade. The use of this I-joist was also shown in roofing and flooring systems. This beam can be used in allowable spans from 2 to 4 m in span for flooring systems and from 5 to 7 m for roofing applications.

There is considerable interest in the development of thermo-hydro-mechanical (THM) treatments to increase the density of low-density woods. However, the development of processes for improving the properties of low-density woods in regions with lower investments in investigations and development, such as tropical areas, is often limited by the equipment and infrastructure constraints. The aim of this work is to outline the development and construction of an inexpensive THM densification device (THM device) that controls the application of heat, load, and steam, by adapting an accessory to a 60-Mg universal testing machine (UTM). The THM device was evaluated using the Vochysia guatemalensis wood (tropical species). The inexpensive densification THM device uses steaming, temperature, and compression and can be adaptable to a 60-Mg-capacity UTM. It also allowed us to successfully conduct the densification process on 20 by 70 by 300 mm wood samples of a low-density tropical species. However, there were some drawbacks discovered: for example, the steam application, pressure, and temperatures were controlled independently, which was not convenient. It would be more convenient to concentrate them in a single control unit. Additionally, a high variation was observed in the compression and stabilization thickness.

Tectona grandis (teak) plantations are being produced with trees from genetic improvement programs, including clonal selection. However, limited information about inheritance of wood properties is available. For studying genetic parameters of T. grandis wood properties and stem diameter two 10-yr-old trials were studied involving nominally 2 sites × 20 clones × 3 replicates × 1 ramet. Clonal variation was observed in: heartwood (HWP), pith (PP) and bark (BP) percentages; green moisture content (IMC) and density (GD); tangential (TS), radial (RS) and volumetric (VS) shrinkage and ratio tangential/radial: shrinkage (ratio T/R); L*a*b* color parameters; and stiffness and specify gravity (SG). Some wood properties evidenced strong across-sites genotypic control. The higher broad-sense heritability estimates (over 0.36) were for PP, IMC, SG, TS, VS and L*, a*, and b* color coordinates and stiffness. Low and non-significant values were estimated for HWP, BP, GD, RS, ratio T/R and decay resistance of sapwood and heartwood to Trametes versicolor and Pycnoporus sanguineus. However, HWP showed marked clone x site interaction. Phenotypic and tentatively estimated genotypic correlations indicate that selecting faster-growing clones will improve some important wood properties, such as increasing HWP, and decreasing PP and BP, without affecting other wood properties. Selecting clones for denser wood, as expected, improved stiffness, should decrease IMC and affect negatively b* (yellow/blue) color. Clone selection with lower L* values could increase redness (a*) of wood.

The aim of this study was to investigate the fuel characteristics (calorific value and fuel value index) of 10 fast-growing species in plantations in Costa Rica. The effect of the chemical properties, extractives and moisture content were evaluated. The results revealed that the gross calorific value varied from 16.5 to 20.6 MJ kg−1 for sapwood, and from 16.3 to 20.1 MJ kg−1 for heartwood. No consistency was observed with regard to which type of wood (sapwood or heartwood) had the highest gross calorific value. Large variations among the species were observed in the case of the fuel value index. For heartwood, the slope gradient of linear correlation was affected by lignin and extractives in sodium hydroxide and dichloromethane solution, whereas in the case of sapwood, only ashes content affected significantly to calorific value. For chemical parameters or the amount of extractives, carbon, nitrogen and lignin contents, ashes and extracts in dichloromethane influenced significantly the calorific value of heartwood. The calorific value in sapwood was affected by the amount of extractives in ethanol–toluene and the amount of ashes. Finally, the fuel value index was affected by the quantity of carbon, the extractives in sodium hydroxide and dichloromethane.