Rendimiento y calidades de chapa en clones de chopo a diferentes alturas del fuste

Some major morphological characteristics in relation to log yield in plywood industries were studied in 13 poplar clones, from Populetum of Zamadueñas (Valladolid). Taper, eccentricity, ovality and bark percentage were analysed. Industrial peeling was made in logs up to 12 m height, analysing the veneer yields and comparing the different quality class among clones at different height levels. Log veneer yields up to 12 m trunk length averaged 60 to 70 % in volume without significant differences among clones. In general, the best performance was found in the middle to lower stem zone. However, clones ‘I-214’, ‘Flevo’, ‘MC’ and ‘PA-1’ maintained their optimum yield even above 10 m height in trunk. ‘Campeador’, ‘I-214’, ‘I-262’, ‘PA-1’ and ‘MC’ showed the best yield and quality performance. ‘Canadá blanco’ and ‘454-40’ have acceptable conditions for this use, but their yield was lower.En 13 clones de chopo, procedentes de una parcela de experimentación ubicada en Zamadueñas (Valladolid), se estudian algunas de las características morfológicas relacionadas con el rendimiento de las trozas para su utilización en la industria del desenrollo. Las variables analizadas han sido: conicidad, excentricidad, elipticidad y porcentaje de corteza. Con las trozas resultantes hasta una altura de 12 m se llevó a cabo una operación industrial de desenrollo, realizándose el estudio del rendimiento y la comparación de las diferentes calidades de chapa obtenidas entre los clones y a diferentes alturas en el tronco. El rendimiento en chapa hasta los 12 m de tronco ha oscilado entre el 60 y el 70 %, en volumen, sin marcadas diferencias entre los clones. En general, el mayor aprovechamiento se produce en la zona media-baja del tronco, pero en algunos casos, el rendimiento óptimo se ha mantenido incluso por encima de los 10 m, como ha ocurrido en los clones ‘I-214’, ‘Flevo’, ‘MC’ y ‘PA-1’. Los clones ‘Campeador’, ‘I-214’, ‘I-262’, ‘PA-1’ y ‘MC’ han sido los que mejor respuesta han manifestado en cuanto a rendimiento y calidad. ‘Canadá blanco’ y ‘454-40’ han dado una calidad aceptable, pero su rendimiento ha sido menor

Características físico-mecánicas de las maderas de especies de crecimiento rápido de procedencia española

29 physico-mechanical and morphological properties of different timbers from five fast growing Spanish tree species were studied and analysed.Se determinan y analizan 29 características físico-mecánicas y morfológicas de maderas de cinco especies de crecimiento rápido de procedencia española (pinos radiata y gallego, chopo, castaño y eucalipto)

Effect of growth conditions on wood density of Spanish Pinus nigra

The natural forests of Laricio Pine (Pinus nigra Subsp. salzmannii) cover in Spain an area of 353,000 ha, producing annually 310,000 m3 of roundwood. This species is considered as the fourth, most important Spanish conifer, being its timber frequently used in construction. The natural area of distribution of Laricio pine in Spain is officially divided into ten different regions of provenance, being only four of them considered as productive. The present study on the influence of growth conditions on extracted wood basic density (EBD) is carried out on 89 P. nigra trees, sampled from the two most productive Spanish regions of provenance (R.7 and R.8) in seven different sites. Cross-sectional disks were cut at 3 m (in 89 trees) and every 3 m height (in 18 trees) from the butt up to 15 m. For assessing the pattern of radial variation of the properties, 20×20×20 mm3 wood samples were taken radially from every cross-sectional disk. In every 20×20×20 mm 3 wood sample, age and distance to the pith of the central annual ring was recorded, together with the average growth rate. Extractive content and EBD were measured in every sample. The results lead to the conclusion that there is not a significant relationship between EBD and provenance or growth rate. On the contrary, a significant relationship has been found between EBD and site quality or cambial age. The results also demonstrate that in a tree EBD tends to diminish from the base to the top and from the pith outwards. The main result of the present study is related with the observation that for the same cambial age, annual ring width has no significant influence on EBD, confirming that its utility as a predictor of the quality of timber is highly questionable, at least if the ring curvature is not considered

Curves for the estimation of the moisture content of ten hardwoods by means of electrical resistance measurements

Accuracy in moisture content measurement is of great importance in the assurance of wood product quality and is necessary to meet administrative and normative requirements. Improving the accuracy of resistance-type moisture meters, and meeting the normative demands of their annual calibration, requires the use of optimised curves relating electrical resistance to moisture content for the most commercially important wood types. The Samuelsson model, adjusted by linear regression techniques, was used to describe the relationship between the electrical resistance and moisture content of seven boreal and three tropical hardwoods available on the Spanish market. The curves produced can be used to predict the moisture contents of these hardwoods via the measurement of their electrical resistance with an error of just ± 1.0%. These curves should also prove of great use in the calibration of wood resistance-type moisture meters