INFLUÊNCIA DA IDADE DE CORTE DE CLONES DE <i>Eucalyptus grandis</i> E HÍBRIDOS DE <i>Eucalyptus grandis </i>x <i>Eucalyptus urophylla</i> NA COMPOSIÇÃO QUÍMICA DA MADEIRA E POLPAÇÃO KRAFT

Abstract

The recent efforts on the quality of the wood used in pulp and paper mills has focused in many points, among them the influence of the raw material chemical characteristics in the production process and final product quality. Considering the current demand for younger trees, the effect of the wood harvesting age in the chemical composition and in the process variables becomes a very important fact for the industries of this sector. So, the objective of this study was to characterize Brazilian eucalypt clones, Eucalyptus grandis and Eucalyptus urograndis, both in different harvesting ages (1 to 8 years-old), for their chemical composition and kraft pulping parameters. Both chemical compositions of wood samples showed significant statistical variations due to the alteration of their harvesting ages. The glucan content, as well as cellulose content, basic density, and extractives tended to rise with the increase of harvesting age; while xylan and the other carbohydrate contents that compose the hemicelluloses tended to decline with the increase of the harvesting age, as well as uronic acids, acetyl groups, lignin, ashes, and S:G ratio. The 5 year-old wood samples showed the greatest pulping yield results for kappa number 17, and the yield at kappa number 17 showed strong correlation with glucan content. Keywords: wood quality; chemical pulping; eucalypt. RESUMOOs recentes esforços na melhoria da qualidade da madeira para o abastecimento das fábricas de celulose e papel têm focado em muitos pontos, dentre estes, a influência das características químicas da matéria-prima no processo produtivo e na qualidade do produto final. Considerando a atual demanda por árvores mais jovens, o efeito da idade de corte da madeira na composição química e nas variáveis de processo, torna-se uma questão importante para as indústrias do setor. Em função disto, o objetivo do presente estudo foi caracterizar clones de eucalipto, Eucalyptus grandis e híbridos Eucalyptus urograndis, ambos em diferentes idades de corte (1 a 8 anos) quanto às suas composições químicas e parâmetros de polpação kraft. Ambas as composições químicas das madeiras mostraram variações estatísticas significativas devido

Wood Quality and Pulping Process Efficiency of EliteEucalyptusspp. Clones Field-Grown under Seasonal Drought Stress

“…For Eucalyptus trees grown in southeastern Brazil, Gouvêa et al [40] mentions pulp yield values from 50.3-52.9%, and Ferreira et al [47] relates pulp yield values between 50 and 55% for Eucalyptus commercial clones at seven-nine years old. Similar results were reported by other authors [48].…”

Spatial Statistics and Age Structure of Leaf Cutting Ant Nests

“…Under these conditions, the Cerrado can act as a refuge area for ants during the Eucalyptus harvest period, as previously verified for other insect species[19] [20]. Refuge areas have been intensely discussed in different con-the growing demand for younger trees, thanks to intense selection of clones[21]. This demand results in the systematic rotation of trees in Eucalyptus areas, a reason why probably ant nests are aggregated in borders, especially between native forest and Eucalyptus plantations or Cerrado and Eucalyptus plantations.With the rotation of trees, the number of leaves available to supply ant nests decreases drastically and incipient nests can be rapidly eliminated, increasing the risk that ant populations will fail to persist.…”

Longitudinal variation of wood quality in the five forest species from Caatinga

“…Mean values of basic density of 740.99 kg m -³ for Myracrodruon urundeuva and 601.96 kg m -3 for Leucaena leucocephala were obtained by Silva et al (2017), while Almeida et al (2015) obtained mean values of 1001.93 and 631.81 kg m -3 , respectively, for Piptadenia stipulacea and Amburana cearenses. These differences can be attributed to variations of growing areas such as temperature, precipitation and soil conditions, in addition to tree age, all of which can directly influence the characteristics of the wood, such as basic density, as verified by Morais et al (2017).…”