Within-Tree Variation of Heartwood, Extractives and Wood Density in the Eucalypt Hybrid Urograndis (Eucalyptus Grandis × E. Urophylla)

Jorge Gominho, João Figueira, José Carlos Rodrigues, Helena Pereira

Abstract


The within-tree variation of heartwood content and the accumulation of extractives were studied in the eucalypt hybrid urograndis (Eucalyptus grandis X E. urophylla) in five 5.6-year-old trees from one clone in a commercial pulpwood plantation in Brazil. Wood basic density was on average 0.491 g/cm-3 and with a small axial variation. Heartwood was present in all the trees up to 65% of total tree height, amounting to 38.8% of the total volume. Within the tree, heartwood decreased from the base upwards, on average representing 51%, 44%, 39%, 32%, and 19% of cross-sectional area at, respectively, 5%, 25%, 35%, 55%, and 65% of total tree height, with a very small between-tree variation. The extractives content of heartwood was double that of sapwood (7.6% vs. 3.7%). The extractives were mostly ethanol and water solubles that showed a trend of decreasing content along the stem from base upwards. Heartwood is a quantitative significant quality parameter in the wood of the urograndis eucalypt hybrid, and its inclusion in selection programs is suggested.

Keywords


Heartwood;extractives;wood density;eucalypt hybrid;urograndis;<i>Eucalyptus grandis × E. urophylla</i>

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