Responsible scientist: Pekka Saranpää, Finnish Forest Research Institute, Vantaa Research Centre
Other participants: Harri Mäkinen, Tuula Jaakkola

To understand the basic relationships between silvicultural practices, tree growth, and wood properties, it is necessary to obtain information about their dynamics throughout the entire rotation of a stand. Detailed measurements will be taken to establish relationships, in the form of statistical models, between environmental factors controlled by silvicultural treatments, tree growth and wood properties. The purpose is to model how stem and wood properties are linked with each other and how they are distributed along the stem from the stem base to apex and from pith to bark.

An existing data-base on wood properties of Norway spruce in different stand conditions will be utilised. Because of imbalanced design with regard to age distribution and coverage of site types, additional sample trees will be collected to harmonise the material. The sampling will be carried out in connection with Task 2 in old thinning and fertilisation experiments established and maintained by Metla. The accuracy of the detailed models in predicting average wood and fibre properties of entire stems and stands will be evaluated with the help of a more extensive data set sampled for Task 2.

Changes in annual ring width, early-latewood ratio, and wood density at different heights alongthe stem will be studied by using x-ray pictures with microdensitometric analysis. Fibre length will be analysed from pith to bark by macerating earlywood samples and measuring 50 unbroken fibres by image analysis system. Fibre width and cell wall thickness will also be studied by image analysis systems using thin sections cut by a cryo-microtome.

In addition, the models of branch characteristics of Scots pine, developed in previous studies, will be evaluated with respect to simultaneous multivariate prediction. Models for branch properties for other main Finnish commercial species (Norway spruce (Picea abies (L.) Karst.), silver birch (Betula pendula Roth.)) are currently under development, using the same modelling framework as the branchiness models of Scots pine.