Effect of contrasting climatic conditions in Brazil on heartwood and sapwood production and chemistry in young Eucalyptus clones

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This study investigated the influence of contrasting climatic conditions on the proportion and chemical composition of heartwood and sapwood in three young Eucalyptus clones grown under different climatic environments in Brazil. Analyses included extractives content, total lignin, syringyl/guaiacyl (S/G) ratio, ash content, and holocellulose, as well as the determination of heartwood and sapwood proportions along the stem. The results showed that variability was more pronounced between heartwood and sapwood than among growth sites. Heartwood exhibited higher extractives and lignin contents and higher S/G ratios, whereas sapwood showed higher ash content. Extractives and ash were the chemical properties most sensitive to environmental conditions, presenting the highest percentage of variation among sites. Clone C4 showed greater chemical stability across environments. Correlation analysis indicated that only extractives content was positively associated with precipitation and potential evapotranspiration. From a technological perspective, the results demonstrate that more restrictive environments tend to intensify chemical characteristics that hinder pulping performance, highlighting the importance of genotypic selection aimed at chemical stability and the control of industrial variability.

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