The Thünen Centre of Competence on the Origin of Timber is the central contact facility for government agencies, timber trade, consumers and associations to verify the species of wood and/or wood products and its origin. To enable reliable wood identification, the Centre of Competence maintains one of the world’s largest scientific wood collections (Xylotheque) comprising over 37,000 specimens representing 12,000 species. These serve as reference material for the macroscopic and microscopic identification of trade timbers.
Which methods are applied for the wood identification?
Macroscopic wood identification: This method is suitable for a first reliable determination of the declared species. For the wood identification, the transverse planes of the submitted specimens are cut (using a cutter or carpet knife) and macroscopically observed with a hand lens (optimal magnification 10 to 12x). In many cases, the wood genus of important trade timber can be already determined on the macroscopic level.
Microscopic wood identification: For official/judicable reports on wood identification, microscopic analyses were routinely carried out at the Thünen Centre of Competence. Applying the light microscopic techniques, up to 100 structural-anatomical characters can be used for a definitive wood identification. The microscopic analyses enable the wood identification of all solid wood specimens including very thin veneer layers (thickness lesser than 0.20 mm) also individual wood strands and chips.
For the macroscopic and microscopic wood identification of solid wood specimens, e.g. scantlings, boards, furniture etc., representative samples with a length of approx. 2 to 10 cm should be taken and sent (postage) to the Thünen Centre of Competence. The minimum size of the samples is restricted to a dimension of approx. 5 to 10mm which allows a preparation without additional embedding procedure. Smaller specimens, e.g. individual veneer layers or fibre particles can be embedded for the preparation of microscopic slides which requires a higher methodological effort. The number of samples for the wood identification depends on the special request, e.g. different wood species in a window scantling or furniture; in case of doubt, several test specimens should be collected and provided.
A differentiation/separation between sapwood and heartwood is not necessary because the wood anatomical structures are unaffected by the synthesis and deposition of heartwood extractives. However, heartwood samples should be preferred (if available) which obtain additional characters for the wood identification. The samples should be provided in dry (air-dry) conditions.
The Thünen Institute processes approximately several hundreds of requests for wood identification annually. They come mainly from the timber trade and trade monitoring (customs, conservationists) sectors.