Abstract
(Englisch)
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Stress is developing along with the formation of wood. It is a result of internal biological, physical and mechanical phenomena which take place during longitudinal and radial growth. Internal stress can also be induced by reactions of the tree responding external influences like gravity, wind, change of competition of neighbouring trees etc. If it comes to the felling and crosscutting of a tree, stress is partly released, often resulting in endsplitting of the logs. Residual stress has serious negative effects on further processing and on the quality of the final products.
European beech (Facus silvatica L.) The most important broad leave tree of Central Europe is known to be extremely sensitive to develop internal and residual stresses. This becomes of growing technical and economical importance, because there is a clear tendency in the market of beech timber towards high quality to produce sophisticated products with high added value, f e. Furniture, joinery, plywood and veneer. Furthermore the growing reluctance of European customers to use tropical timber contributes to this trend, because beech is an alternative for many respective wood products. National Silvicultural programms throughout Central Europe favour broad leaves and especially beech due to ist fovourable ecological profile, but there is a deficit of specific beech-related wood quality research. Significant scientific work has been done in the field of wood anatomy and physiology to understand the phenomena which lead to the development of internal stress. But there is a lack of comprehensive information about the relation between silvicultural treatment and the tendency of beech trees to develop stress, and practicable strategies to assess and to early - detect stresses are lacking, too. Furthermore, there is no clear picture about the technical and economical consequences of residual stresses in the different sectors of utilising high value beech timber, and there is few reliable experience how their negative effects for productions and products could be minimised or even overcome through adapted technical treatment and processing through-out the forestry-wood-chain.
This proposal ' Stresses in Beech' aims to contribute to close these gaps of knowledge by an integrated approach on European level. On the basis of well defined experimental trees which show stress phenomena coming from stands with significantly different site conditions and silvicultural history, laboratory analysis of small wood samples and experimental industrial-scale processing will be carried out. High quality sawn timber, rotary cut and sliced veneer will be produced under controlled conditions. On all steps of the forestry-wood-chain from the forest to these end products, possibilities to detect, to evaluate and to prevent stress and it's negative impacts on the quality of beech timber and related products will be investigated, analysed and evaluated. Through the exchange of data, methods and material, the variance of the beech resource throughout central Europe will be covered and investigated. The results will help to minimise the negative effects - in short term by stress-adapted treatment and processing, and - in the long run - also by modifying silvicultural practise, aiming at a reduction of growth stresses.
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