Analyses of basic crown-stem growth relationships in Radiata pine

The variability of wood properties is an important issue in the utilisation of wood and fibre. Over recent decades there has been increased emphasis on intensively managed, short rotation, plantation forestry, that produces larger proportions of so-called juvenile or core wood. This situation seems to have been aggravated by the shift to establishing forests on high-fertility farm sites, and earlier harvest ages, further increasing variability and lowering wood quality. The exact causes of the increased variability are not well known. It is well recognised that researchers and foresters need tools incorporating models of wood properties and that models of tree growth and wood quality must be linked to allow realistic representation of the variation in wood properties in response to environmental factors and management practices. By attempting to use crown growth to predict wood properties it is intended to explain well known patterns of variation in wood properties, such as: the change from juvenile wood, with wide rings and low density; to mature wood, with narrow rings and high density. Three hypotheses relating crown and stem growth are to be tested using crown and stem data from a single intensively measured tree, summarising research carried out for a M.Sc. thesis (Pont 2003). The hypotheses are based on the theories of: Pressler (in Assmann 1970), Larson (1962 and 1969), and the pipe model theory (Shinozaki et al. 1964) respectively: Stem ring area increment at a level on the stem is proportional to the mass of foliage above. Ring basic density at a level on the stem is proportional to the amount and proximity of foliage above. Stem sapwood area at a level on the stem is proportional to the mass of foliage above.