WP3 – Modelling Wood Quality

Here the focus is on wood quality and how this is affected by different silvicultural practices. There are two objectives:

  1. Model the effects of silviculture practices on wood properties of standing trees and harvested roundwood;
  2. Develop recommendations to forest practitioners on the choice of future silvicultural practices and provenance for each area in the context of climate change.

The first task is to review the existing modelling approaches and to define our research gaps in terms of management type. From there we will develop “national” modelling approaches, which will be cross-validated with existing data and between countries. The work will include the production of a decision support tool for selection of management practices to produce wood with specific quality characteristics. This will provide suitable silvicultural and management practices, given site and species details, to produce wood with specific end-user defined quality characteristics.

The study goes on to quantify the impact of intensified silvicultural practices on the growth of Sitka spruce and Douglas fir using data derived from external and internal quality characteristics. Measurements will be taken from trees in forests and research trials that have had various treatments applied (thinning and spacing), but the exact approach will depend on availability of material in each country. Core wood samples will be taken near breast height from a subsample of trees to estimate density, proportion of early wood and late wood over periods of the rotation. Information on branching characteristics (distance to live crown, size and number of dead branches in lower bole) will be recorded. Similar information will be recorded from one provenance trial per species in each country, based on four provenances that overlap in latitude of origin (since the provenances will not be identical in each country).

The aim of the next part of this study is to determine the influence of intensification practices on structural characteristics of timber. These will be determined using a subsample of trees growing in the stands/ trials (excluding the provenance trials). The allocation of a particular board to a specific structural strength class is defined in EN338 (2009). The allocation is based on the characteristic values of the density, modulus of elasticity in bending and bending strength. Structural testing of the processed boards will be undertaken in accordance with EN408 (2012) to determine the modulus of elasticity in bending and the bending strength of each board. Density and moisture content at the time of testing will also be determined. Characteristic values of the density and mechanical properties in bending properties will be determined in accordance with EN384 (2010). Links between the proportion of material in each grade and the stand/trial of origin will be established to determine the influence of intensification and climate. In addition to the testing to EN408, measurement of timber characteristics including juvenile wood, (variation in) ring width, knot area ratio and sloping grain will be made to determine which characteristics significantly affect structural quality. Data will be downloaded from a 3-D log scanner, which is used at the start of the production process in a saw mill, to provide detailed physical log characteristics. In addition, data will also be collected later in the production process from an X-ray board scanner and grader.

On completion of the work described above the next element of the project is to determine the impact of future silvicultural practices and climate change on wood properties and tree assortments. The impact of future silvicultural practices and climate change on wood properties and tree assortments using external and internal characteristics will be modelled. The aim is to predict wood properties to meet specific end-product objectives from external tree characteristics using variable inputs such as silvicultural practices and provenance, and vice versa, to provide suitable silvicultural and management practices to produce wood with specific properties.