New Zealand Journal of Forestry (2004) 49(3): 24–31
©New Zealand Institute of Forestry
Juvenile wood (sensu novo) in pine: Conflicts and possible opportunities for growing, processing and utilisation
R. Burdon , J. Walker , B. Megraw , R. Evans and D. Crown
Wood near ground level in stems of Pinus radiata and P. taeda typically has some distinctive properties, even in relation to ring number from the pith. These properties have recently prompted advocacy of using the term juvenile wood for this zone near ground level. This involves a new, two-way classification of wood zones within the stem, with a vertical progression from juvenile to mature wood and a radial progression from corewood to outerwood. The vertical differences in wood properties, ring for ring from the pith, occur in conjunction with vertical variation in branch habit and therefore in knot characteristics.
Conflicting considerations arise for processing and utilisation of this redefined zone of juvenile wood. One conflict arises between poor stiffness of juvenile wood, which does not favour structural uses, and a knot pattern in this zone that would otherwise commend it to structural uses in unpruned material. Another conflict, involving P. radiata, is between the poor stiffness commending juvenile wood to appearance grades and the susceptibility to instability and to internal checking in drying. Careful segregation of juvenile wood for processing may greatly mitigate these conflicts. Alternative or complementary approaches, for the longer term, can include stand-management measures, use of cuttings instead of seedlings, and genetic improvement.
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