The project, which seeks to inform the wood processing industry in North Scotland about the quality of the current and future Scots pine resource, comprises four tasks:
- Analysis of current utilisation of Scots pine
- Development and testing of timber quality assessment methods
- Assessment of the end-use quality of standing Scots pine
- Market development study
Analysis of current utilisation of Scots pine
This part of the project comprised an analysis of Scots pine timber harvested in North Scotland, considering where it was processed, end-uses and the timber quality requirements for different markets.
Questionnaires regarding Scots pine management, harvesting, processing and product manufacture were distributed to growers, processors and end-users in March 2006. Visits to end-users supplemented questionnaire responses.
The full report can be downloaded below. The key findings of the survey were:
- Responses from forest owners/growers covered 57,766 ha of Scots pine forests, 53% of the area of Scots pine forest reported in the National Inventory of Woodlands.
- Results of the growers’ questionnaire indicated that the average age of 1st thinning for Scots pine was 30 years, that the split between clearfell and Continuous Cover Forestry (CCF) was 43%:57% and that the average age at clearfell was 62 years.
- Respondents to the growers’ questionnaire reported that just under 207000 m3 of Scots pine timber was harvested during 2005. This compares to 325600 m3 reported as having been processed in the processors’ questionnaire and the forecast availability for the study area of 505000m3.
- 50% of the timber harvested was processed into panel board products, with a further 40% processed for agricultural and domestic fencing.
- 60% of the volume of Scots pine sawn timber and timber products was sold through timber merchants, builders’ merchants and DIY chains.
- Key timber quality criteria for Scots pine logs were identified by growers and processors as bluestain, straightness, knottiness and size. Ovality, taper and crop uniformity were also judged to be important.
- Concerns about quality were focused on variability and the inability to predict internal characteristics. Black knots were seen as a major defect. Task 2 of this project is aimed at developing techniques to assess timber quality in standing trees.
Market Requirements and Resource Availability report (PDF-482K)
Development and testing of timber quality assessment methods
Acoustic testing Scots pine
Scots pine battens
Three sample stands were studied to evaluate the potential of a number of non-destructive timber quality assessment methods (stem straightness score, various branching assessments, standing tree and log acoustic tools) for prediction of log grade out-turn, sawn timber mechanical properties and appearance grade.
Stem straightness score and height of lowest dead branch were found to be the best measurements for predicting green log yield. This finding was supported by results of further testing of standing tree assessment methods in an additional three sample stands. A model predicting sawn timber stiffness from HM200 log acoustic measurements was developed.
Task 2 - Timber quality assessment methods update (PDF-465K)
Napier University’s Centre for Timber Engineering determined selected wood properties for a sub-sample of the sawn structural timber cut from the three original sample stands. A full report of this work is available:
Report on the investigation of mechanical properties of structural timber from three stands (PDF-282K)
The dynamic modulus of elasticity (Ed) was determined for each piece of timber from measurements of stress wave velocity, made with a portable acoustic instrument, and bulk density. Four-point bending tests were conducted on the same samples of timber to determine global static modulus of elasticity (MOEG) and modulus of rupture (MOR). Basic density was determined gravimetrically from smaller samples cut from each piece of timber. Each piece of timber was uniquely coded so that it could be linked back to a specific log, tree and stand.
The characteristic values of bending strength and stiffness, and basic density were sufficient for the timber to meet the requirements for the C20 strength class. The strength class that the timber could achieve was limited by its strength and stiffness rather than by wood density. By segregating out those logs which had low stress wave velocities, as measured using the HM200 acoustic tool, it was possible to achieve the requirement for the C22 and C24 strength classes. Only a small number of logs (12.5%) were segregated out to meet the requirement for the C22 strength class, but 65% of the population of logs had to be segregated out in order to meet the requirements for the C24 strength class. It was also possible to segregate material based on standing tree velocity measurements, but this was less efficient..
Assessment of the end-use quality of the standing Scots pine
The objective of this work is to undertake a strategic assessment of the end-use properties of the standing Scots pine resource in North Scotland, using the assessment methods tested in Task 2, i.e. stem straightness score, height of lowest dead branch and acoustic assessment in standing trees and logs.
Two approaches are being used:
- A survey of Scots pine stands in Grampian and Highland, targeted on stands likely to be harvested before 2030 is ongoing in a sample of 100 stands.
This will provide an assessment of timber quality of Scots pine likely to be marketed in next 20 years. Data will be analysed to quantify the effects of site conditions and silviculture on timber quality. - Acoustic assessment of logs from across north Scotland.
The HM200 log acoustic tool is being used to map resource characteristics of Scots pine. Samples of logs are being measured on delivery to sawmills and the results linked to site location and stand characteristics.
Market development study
A market development study evaluating potential new market opportunities for Scots pine timber was commissioned from Napier University CTE and conducted by Ivor Davies. Thirteen products were assessed against a number of technical and commercial criteria to identify those with the greatest potential for value added market development. The products highlighted were massive wood construction (Brettstappel), external cladding, garden and landscaping products (focused on the potential for wood modification by chemical or thermal treatment), playground equipment and stress laminated timber bridges.
Market development study report (PDF-823K)
Northern Periphery Programme Project – “Developing the Pinus sylvestris resource”
Forest Research is participating in this collaborative project which involves partners in Scotland, Finland, Norway and Sweden, with the aim of stimulating the development and utilisation of Scots pine timber as a basis for supporting sustainable rural enterprises. The project, which is led by Highland Birchwoods will run from 2008 – 2011. Forest Research’s activities within the project are focused on timber quality assessment methodologies, modelling and forecasting quality and best practice guidance for silviculture to grow quality timber.
Further details about the "Developing the Pinus sylvestris resource" project.
