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Impact of silviculture on timber properties
Summary Sitka spruce spacing trial at Baronscourt, Northern Ireland In general, the spacing between trees in UK plantations is kept under 2 x 2 metres based on the recommendations of Brazier and Mobbs (1993) . This project, which is part of the silviculture and timber properties research programme, is aimed at re-evaluating this practice and validating a computer model developed to predict the wood properties of Sitka spruce. The will help to increase understanding of the utilisation of Sitka spruce grown in the British Isles and improve future forest management. Detailed objectives- To provide new information on the effect of spacing on timber properties and performance
- To provide material to run a validation of our timber quality model and test its suitability for Northern Ireland Forestry
- To re-calibrate our timber quality model in the light of the results obtained above
- To provide data on the long-term retention of Sitka spruce stands.
Forestry Commission policyTimber is one of the key themes of the Scottish Forestry Strategy. This project will contribute to several of the requirements identified in the Strategy, namely: - To maximise the economic potential of Scotland’s timber resources.
- To promote the use of timber as a renewable, versatile raw material.
- To encourage the production of high quality timber.
Methods Sample tree being felled in the Barsonscourt sample plots A tree spacing experiment planted in 1949 on the Baronscourt Estate, Northern Ireland, is being studied with sample material from five treatments being investigated: 1.8 x 1.8m, 1.8 x 3.7m, 3.7 x 3.7m, 3.7 x 5.5m, 5.5 x 5.5m. (Each treatment was replicated five times in a Latin square design). The samples were collected during the summer of 2006. 1700 battens were cut at Balcas sawmill in Enniskillen and transported to Scotland to be X-ray graded in Wilson’s of Troon sawmill. The detailed wood properties of the battens are now being assessed in collaboration with Napier University. The parameters being measured are: - Tree volume
- Green log volume
- Standing tree acoustic velocity
- Stem straightness score
- Branch characteristics (Number, status, size, insertion angle)
- Pass rates at C16
- Modulus of elasticity (MOE) and modulus of rupture (MOR) of battens
- MOE and MOR of clear wood samples
- Relative density of the clear wood.
Status Felled tree being acoustically tested using the Hitman acoustic testing tool The project has been running since June 2006 and will be ongoing until mid-2008. All of the standing tree, branching and log assessments have been completed and we are currently destructively testing battens and small clear samples in order to determine the static timber properties. Project funders, partners and people ContactFor further information contact: Barry Gardiner
Forest Management Division
Northern Research Station
Roslin, Midlothian
Scotland, UK
EH25 9SY Tel: +44 (0)131 445 6956
Fax: +44 (0)131 445 5124
Email: barry.gardiner@forestry.gsi.gov.uk ReferencesBrazier, J.D. and Mobbs, I.D. (1993) The influence of planting distance on structural wood yields of unthinned Sitka Spruce. Forestry 66 (4): 333-352.
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