Effect of age and diameter class on the properties of wood from clonal Eucalyptus

Abstract

ABSTRACT:The objective of this work was to evaluate the infl uence of age and diameter class on the physical, thermal and chemical characteristics of a clone of Eucalyptus grandis and Eucalyptus urophylla. The material originated from a reforestation site owned by GERDAU S.A. and included trees at age 34, 48, 61, 74 and 86 months. Two trees were selected per age in each diameter class, observing the proportion of each established plot. Analyses of physical characteristics included wood basic density, dry matter weight and carbon stock, and of chemical characteristics included holocellulose, total extractives content, total lignin and ash content, in addition to elemental and thermal analysis of the wood. Results led to the conclusion that most wood properties were infl uenced by age and diameter class. The species was found to have great potential for production of biomass and generation of heat energy, potentially convertible into mechanical energy and electricity.Key words: Growth, wood quality, energy production. EFEITO

Elemental Chemical Composition of Forest Biomass at Different Ages for Energy Purposes

“…In the same way that increasing trends over time were observed for the carbon content in A. mearnsii ( Figure 1A) and E. grandis ( Figure 1B) leaf compartments, this characteristic was also observed for the hydrogen content in the E. grandis (Figure 1D), A. mearnsii ( Figure 1E) and M. scabrella ( Figure 1F) leafs. These positive trends over time are highly desired for an energetic material and corroborate with Santana et al (2012) in working with trees between 34 and 48 months, who observed the best values of these elements which therefore suggested better energy values and less impact to the environment.…”

“…For oxygen, the highest mean values were reported for wood in the four species studied, with 48.93% for M. scabrella, and not differing from A. mearnsii and E. grandis (Table 2). When comparing these to the literature, in determining the variability in the characteristics of E. grandis and E. urophylla wood used as energy source, Santana et al (2012) found higher average values for carbon (48.72%) and hydrogen (6.55%) than those observed in this work and lower nitrogen (0.12%) and oxygen (44.57%) values.…”

“…When the significant equations were analyzed over time for the fifth year after planting, there was an increasing tendency in the carbon content for the bark and the leaf of A. mearnsii (Figure 1A), for E. grandis leaf ( Figure 1B) and for A. glazioviana wood ( Figure 1C). Santana et al (2012), who also found higher carbon values in older trees, suggested that carbon levels tend to increase as tree size increases, as well as being directly proportional to biomass production. For the same authors, this significant increase in the carbon content with the advancing age is much desired when the objective is to destine the biomass to produce energy, since it positively contributes to the calorific power.…”

“…These differences observed in the interactions related to the chemical composition of the biomass within a single tree are related to age, genetic factors and ecological conditions of the environment, which provide variations in the response to the formation of young wood and adult wood. It is clear that chemical properties are subject to substantial initial variations in juvenile wood, but tend to stabilize as adult wood begins to form (Santana et al, 2012). For Eloy et al (2014), factors related to the structural composition of wood influence its energy potential, mainly with respect to the chemical and elemental constitution.…”

Características de crescimento, composição química, física e estimativa de massa seca de madeira em clones e espécies de Eucalyptus jovens

“…Avaliar os efeitos que podem influenciar a qualidade da madeira é necessário para conhecer as variações sofridas pelas diferentes propriedades, tanto nas espécies como nos clones plantados industrialmente. SANTANA et al (2012), avaliando o efeito da idade e da classe diamétrica nas características da madeira de um clone de eucalipto plantado no sul de Minas Gerais, verificaram que a idade influenciou significativamente nas propriedades físicas, químicas e térmicas da madeira, exceto o teor de holocelulose, carbono e oxigênio elementares. Observaram, também, que a classe diamétrica exerceu grande influência sobre as características da madeira.…”