Relação entre a densidade e razão isotópica do carbono da madeira de Eucalyptus grandis submetida ao déficit hídrico
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Data
2020-07-28
Autores
Bruder, Edson Marcelo [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As florestas do gênero Eucalyptus apresentam uma grande importância econômica. A matéria-prima gerada apresenta uma plasticidade adaptativa aos diversos tipos de clima e região, além de sua diversidade de aplicação. O estudo avaliou e correlacionou a densidade (ρ) e a razão isotópica de Carbono (δ13C) na madeira de árvores submetidas ao déficit hídrico em reflorestamento comercial, de origem seminal e clonal de Eucalyptus grandis. A ρ é um dos indicadores de qualidade e controle das florestas plantadas, e os valores isotópicos δ13C indicam respostas fisiológicas à restrição hídrica. O déficit hídrico foi realizado com exclusão artificial de um terço da água de precipitação no solo. A ρ foi determinada pela atenuação da radiação gama do 241Am e os valores de δ13C a partir de um sistema de fluxo contínuo de espectrometria de massa de razão isotópica. Os valores pontuais da ρ e δ13C na direção radial dos discos foram utilizados para o cálculo da média ponderada nos discos, nas árvores e nos tratamentos. Foram realizadas correlações entre os valores de ρ e δ13C na direção radial dos discos, longitudinal das árvores e nos valores médios dos tratamentos. As procedências submetidas ao tratamento com e sem déficit hídrico não apresentaram diferenças significativas. A ρ estimada na posição de 12,5% da altura total, pode auxiliar na estimativa da ρ, alcançando resultados muito próximos aos valores médios da árvore. Os tratamentos submetidos ao déficit hídrico apresentaram diminuição no volume final. Os resultados mostraram que a ponderação da ρ média da árvore poderá ser estimada com uma diminuição da amostragem na direção longitudinal mantendo a mesma precisão. A ρ média entre as procedências seminal e clone, não apresentaram diferenças significativas. A ρ e δ13C na direção radial dos discos apresentaram correlação, enquanto os valores médios apresentaram uma relação direta. As análises da ρ e δ13C possibilitaram identificar a variabilidade nos tratamentos e evidenciaram a possibilidade de uma metodologia para a investigação da qualidade da madeira.
Eucalyptus forests are of great economic importance. The raw material generated has an adaptive plasticity to different types of climate and region, in addition to its diversity of application. The quality of eucalyptus forests is directly correlated to genetic factors, climatic conditions and soil quality, which directly influence wood productivity and quality. The study evaluated and correlated the density (ρ) and the carbon isotope ratio (δ13C) in the wood of trees submitted to hydric deficit in commercial reforestation, of seminal origin and clonal of the species Eucalyptus grandis. The ρ is used as an indicator of quality and control of planted forests, and the δ13C isotopic values, indicate physiological responses to hydric deficit. The hydric deficit was achieved with the artificial exclusion of one third of the precipitation water in the soil. The ρ was determined by gamma-ray attenuation of 241Am and the values of δ13C from a continuous-flow system of isotopic ratio mass spectrometry. The point values of ρ and δ13C in the radial direction of the discs were used to calculate the weighted average of the discs, trees and treatments. Correlations were made between the values of ρ and δ13C in the radial direction of the discs, longitudinal of the trees and in the mean values of the treatments. The species submitted to treatment with and without hydric deficit did not show significant differences. The ρ estimated at the position of 12.5% total height, can assist in the ρ estimate, achieving results very close to the tree. The treatments submitted to hydric deficit showed a decrease in the final volume. To investigate the average density of the tree it can be determined with a decrease of the sampling in the longitudinal direction. The mean ρ between seminal and clone, did not show significant differences. The ρ and δ13C in the radial direction of the disks showed a relationship, while the mean values showed a direct relationship. The analysis of ρ and δ13C made it possible to identify the variability in treatments and showed a methodology for the investigation of wood quality.
Eucalyptus forests are of great economic importance. The raw material generated has an adaptive plasticity to different types of climate and region, in addition to its diversity of application. The quality of eucalyptus forests is directly correlated to genetic factors, climatic conditions and soil quality, which directly influence wood productivity and quality. The study evaluated and correlated the density (ρ) and the carbon isotope ratio (δ13C) in the wood of trees submitted to hydric deficit in commercial reforestation, of seminal origin and clonal of the species Eucalyptus grandis. The ρ is used as an indicator of quality and control of planted forests, and the δ13C isotopic values, indicate physiological responses to hydric deficit. The hydric deficit was achieved with the artificial exclusion of one third of the precipitation water in the soil. The ρ was determined by gamma-ray attenuation of 241Am and the values of δ13C from a continuous-flow system of isotopic ratio mass spectrometry. The point values of ρ and δ13C in the radial direction of the discs were used to calculate the weighted average of the discs, trees and treatments. Correlations were made between the values of ρ and δ13C in the radial direction of the discs, longitudinal of the trees and in the mean values of the treatments. The species submitted to treatment with and without hydric deficit did not show significant differences. The ρ estimated at the position of 12.5% total height, can assist in the ρ estimate, achieving results very close to the tree. The treatments submitted to hydric deficit showed a decrease in the final volume. To investigate the average density of the tree it can be determined with a decrease of the sampling in the longitudinal direction. The mean ρ between seminal and clone, did not show significant differences. The ρ and δ13C in the radial direction of the disks showed a relationship, while the mean values showed a direct relationship. The analysis of ρ and δ13C made it possible to identify the variability in treatments and showed a methodology for the investigation of wood quality.
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Palavras-chave
Silvicultura, Eucalyptus, Reflorestamento, Densidade, Razão Isotópica, Reforestation, Water restriction, Precipitation