Particle size is a physical property that sometimes limits the quality of briquettes, so it is recommended to use different sizes in mixtures for their manufacture. The objective of this research was to evaluate the effect of different particle sizes of sawdust in mixtures on some physical, mechanical, and energetic properties of briquettes made from Pinus durangensis sawdust, as well as set the ranges within the appropriate values found to obtain desired values. Three particle sizes were established (large, medium, and small), and 10 mixtures were prepared using different percentages of each particle classification. The particle density, volumetric swelling, compressive strength, impact resistance index (IRI), and gross calorific value of the briquettes were evaluated. For the determination of optimal mixtures, the surface response methodology was used under a three-factor simplex-lattice model. The particle density values were in the range 0.92 to 1.02 g cm⁻³ and the volumetric swelling was 0.96 to 3.9%. The highest resistance to compression was 37.01 N mm⁻¹, and the IRI was found in the range of 53 to 107%. The gross calorific values were from 19.35 to 21.63 MJ kg⁻¹. The selection of different particle sizes for the mixtures increases the quality of the briquettes.

Research Highlights: Analyzing the contrasting ecological gradients makes it easier to understand the influence of climate on carbon accumulation. Background and Objectives: The increasing climatic variability has implications for vegetation, impacting on its ecological functions, among which carbon accumulation stands out. In the present study, we used climate-dendrochronology relationships to evaluate carbon accumulation in two conifer species that grow in contrasting humidity sites: Pinus strobiformis Engelm (mesic sites) and Pinus leiophylla var. chihuahuana (Engelm.) Shaw (arid sites). Materials and Methods: Using a dendrochronological approach, we estimated the correlation of biomass and carbon accumulation of each species with some climatic variables (temperature, precipitation, and a drought index) and generated a linear mixed model. Results: The response in carbon accumulation between species with respect to climate was significantly different. P. strobiformis showed a positive correlation with the climatic variables analyzed, while in P. leiophylla the correlation was negative, except with precipitation. Conclusions: These results show that forests in both mesic and arid sites are prone to climate changes, although their responses are different, impacting the productivity and carbon cycles of forest ecosystems.

Agave durangensis Gentry biomass, as a residue from the mezcal production process, may be an interesting bioenergy alternative; however, its high ash content limits its application. In this study, pellets were generated with agave fiber mixed with Pinus species sawdust in the following six proportions (%): 100–0 (control), 80–20, 60–40, 40–60, 20–80 and 0–100 (control). The physical, chemical and energetic properties of the pellets were evaluated according to the UNE-EN ISO 17225-6, UNE EN ISO 17827-2, UNE-EN ISO 17828, UNE-EN ISO 18122, UNE-EN ISO 18123, UNE-EN ISO 18125, and UNE-EN ISO 18134-1 standards. The results showed significant statistical differences (p < 0.05) among the treatments tested. The percentage of volatile material and fixed carbon ranged from 86.53 to 89.96% and 4.17 to 8.16%, respectively; the ash content ranged from 0.27 to 10.06%, and the calorific value ranged from 17.33 to 18.03 MJ/kg. Bulk density ranged from 725.76 to 737.37 kg/m³ and the impact-strength index was in the range of 69.33 to 126.66. The mechanical hardness and compressive strength were found to be in the ranges of 50.5 to 68.4% and 0.90 to 36.65 N/mm, respectively. Pellets generated with Agave residue mixture ≤ 40% were identified as promising biobased resources for the sustainable production of renewable energy.

Nondestructive methods are a fast and accurate way to obtain information about the mechanical properties of plywood panels. The objective was to determine the modulus of rupture and compare the modulus of elasticity (MOE) in plywood boards made with Pinus spp. and Eucalyptus urograndis using the destructive method of three-point static bending and the nondestructive method of ultrasound in parallel and perpendicular directions, as well as in complete board and test specimens, both with the ultrasound method and the correlation between the variables studied. The plywood boards evaluated were 18, 25 and 30 mm nominal thickness. Five structures were evaluated using pine and pine–eucalyptus veneers. Three boards were collected per structure, and 28 specimens were made from each board (14 in a parallel direction and 14 in a perpendicular direction). The elastic modulus was determined by the ultrasound method in complete plywood boards and in specimens obtained from them using the IML Micro Hammer^® equipment and through the conventional bending test, carried out in an Instron^® universal mechanical testing machine. The Tukey test of means (p < 0.05) shows that in the nominal thickness of 18 mm, the modulus of elasticity by ultrasound was lower compared to the result obtained by static bending in four of the five structures in the perpendicular direction and lower in all the structures evaluated in the parallel direction; while in the nominal thickness of 25 and 30 mm, it was greater in all structures and in both directions. The results of static bending by ultrasound, in complete boards and specimens, show that the only significant difference (p < 0.05) occurs in the nominal thickness of 30 mm in the treatment made with pine–eucalyptus with urea formaldehyde resin being lower in the parallel direction and in complete boards The correlation between the modulus of elasticity determined on specimens using the nondestructive method and the destructive method was r = 0.75 and Pr < 0.05; while comparing the nondestructive method on test specimens and complete plywood panels, r = 0.73 and Pr < 0.05 were obtained. It is concluded that the mechanical bending property of plywood boards can be characterized by the ultrasound method.

La densidad básica de la madera puede variar ampliamente en un individuo en el sentido radial; esta característica es inherente a la especie o está influenciada por la edad, la forma del árbol, las diferencias genéticas, la velocidad de crecimiento y la historia evolutiva. El presente trabajo aborda dicha variación en Pinus patula., proveniente de tres localidades del estado de Hidalgo: El Reparo, Tres Fracciones de Fondones y El Aguaje ubicadas en los municipios de Zacualtipán y Metzquititlán. En cada una de ellas se seleccionaron aleatoriamente 20 árboles, y se obtuvo, con el taladro de Pressler, un cilindro de madera de 12 mm de diámetro, a una altura de 1.30 m del fuste para determinar la densidad básica por anillo de crecimiento, mediante el método de máximo contenido de humedad. Para el análisis de los datos, se aplicó un análisis de varianza y una comparación de medias con la prueba de Tukey (a=0.5). Se probaron los modelos estadísticos que mejor se ajustaron a las tendencias presentadas por la densidad básica. Los resultados muestran una media general de 0.4602 g cm-3, un valor mínimo de 0.2241 y uno máximo de 0.6856 g cm-3. Se determinó que la densidad básica de Pinus patula presenta dos tendencias de variación radial en las tres localidades estudiadas: en la primera se observan incrementos a partir de la médula, en dirección de la corteza, y en la segunda los incrementos van de la médula hasta un punto máximo, para después disminuir al llegar a la corteza.

Las plantaciones forestales comerciales son una estrategia para proteger de la sobreexplotación a los bosques naturales, por lo que es importante, conocer las propiedades físicas de su madera. El objetivo del trabajo fue determinar la calidad de la madera con base en sus propiedades físicas, y la cantidad de biomasa en una plantación de Pinus engelmannii de 17 años. El diámetro normal y altura total se midió en todos los árboles encontrados en 20 sitios rectangulares de 3.0 x 6.0 m distribuidos en cuatro líneas. En cada sitio, con un taladro de Pressler se tomó un núcleo de crecimiento a 1.30 m de altura, en dos árboles dominantes. Las propiedades físicas, densidad básica (DB), contenido de humedad (CH), contracciones volumétricas totales (CVT), y punto de saturación de la fibra (PSF) se determinaron aplicando las fórmulas específicas de cada componente. La biomasa se estimó con los valores de volumen y densidad básica, además de tres ecuaciones alométricas. Los resultados indican que la DB fue de 0.379 g cm−3, CH de 199.37%, CVT de 13.63%, PSF de 39.28% y promedio de biomasa fustal de 22.79 kg. El ANOVA mostró que la sección dentro del árbol influyó de manera significativa (p < 0.05) en DB y CH, con correlación negativa (r = - 0.96). La madera de la plantación es homogénea con respecto a la DB, CH y CVT, mientras que las dos primeras variables presentaron variación radial. La biomasa presentó relación con la densidad básica y el diámetro normal.