LINKING GROWTH MODELING TO TIMBER QUALITY ASSESSMENT FOR NORWAY SPRUCE

The aim of this paper is to propose a consistent framework for analyzi ng the influence of silviculture, site quality and, to some extent, ge netics on the wood production of Norway spruce from both a quantitativ e and a qualitative point of view. Tree and stand volume, stem taper, wood basic density, proportion of juvenile wood as well as knottiness are considered as the result of growth processes. Two complementary ap plications are presented. (1) An average-tree growth model which is bu ilt of several interrelated processes: site quality has an effect on h eight growth and hence on all other tree and stand characteristics; cr own development is driven by height growth and controlled by stand den sity; stand basal area increment is predicted from empirical rules; tr ee basal area increment is then distributed along the stem. (2) A mode l that aims at assessing timber quality of a standing tree from usual inventory measurements such as tree age, height and diameter at breast height: growth equations are used to reconstruct the past growth of a tree and to predict its current internal structure, namely ring distr ibution. Both models are linked to allometric equations that estimate the characteristics of branchiness, to densitometric models that predi ct wood basic density from ring distribution and to a software that si mulates the grading of any board located in a stem whose morphology is known in detail. The aim of these models is not to make precise quant itative predictions but to show how different pieces of knowledge of s ilviculturists, forest biometricians and wood scientists may be brough t together in simulation software in order to help forest managers and wood industrialists to make decisions. This framework could be extend ed to other fast-growing coniferous species.