Variación de la densidad de la madera y rendimiento pulpable en clones de Eucalyptus globulus evaluado con espectroscopía de infrarrojo cercano
SUMMARYDensity variation, being the timber longitudinally measured, and the precision of spectroscopy of near infrared (NIR) were evaluated to predict density and pulp yield in two Eucalyptus globulus clones. Furthermore, variability in volume and in NIR predictions was evaluated in four E. globulus clones represented in two growth sites. Clones were selected by means of two trials: 10 and 11 year old clones in two sites from Araucanía Region, Chile. From each selected ramet, shavings samples at breast height diameter (BHD) were obtained to NIR predictions. Additionally, of a subgroup of ramets, chips samples from all the timber and six disks BHD, 20 %, 40 %, 60 %, 80 % and 100 % of commercial height were obtained. NIR predictions were contrasted with values obtained for chips and disks by means of standard error of prediction (SEP) and bias. Variance analyses of two factors (clones and sites) and correlation analyses were used. Density showed an increase from the base to the apex in both clones, though with a different variation profile; consequently, clones presented a different mean density, nonetheless their BHD was similar. NIR predictions showed an error inside the rank given for E. globulus, being those from pulp yield especially exact. Concerning volume, density and pulp yield showed low variability, both among clones and response to the site as well.
Productivity and costs of two low-investment biomass harvesting systems applied in a situation of mixed forest of semi-natural regeneration Productividad y costos de dos sistemas de aprovechamiento de biomasa de baja inversión aplicados en una condición de bosque mixto de origen seminatural
Moisture content is considered one of the most important quality parameters in wood fuels. In this context, natural drying is a cheap and easy method to reach adequate moisture content in forest biomass. The objective of this study is to evaluate the effect of different treatments feasible to be applied operationally in the natural drying of whole small trees. Whole trees from natural regeneration of Acacia melanoxylon with diameters of 3 to 12 cm were used in this research, in Los Ríos Region, Chile. Trees were stacked into piles outside the forest between January and December 2012, distributed in 12 biomass piles. Piles were evaluated at two heights (one and two meters), and two protection levels (without protection and using a semi-permeable cover). A factorial design with three repetitions per treatment was used. Indirect measurements of moisture content were obtained by monthly weight records. These were used to model the progress of drying in each pile. The overall effect of treatments was evaluated with factorial variance analysis using the GLM procedure. For the study conditions, results indicate that natural biomass drying has a strong seasonal component. Consequently the use of cover was essential in winter season. During summer months the cover was not necessary, being able to reach moisture content lower than 30 % after the summer if storage started in the beginning of January. In this case, better results were obtained with the two-meter-high piles because they were less sensitive to occasional summer rains.
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