Tracking down the species and origin of wood with genetic methods

Distinguishing oak wood from beech wood is reliable and also relatively easy with a magnifying glass and microscope. However, the wood of the different oak species that exist in the world is very similar. This becomes a problem in international trade, because there are rare species that are protected, while other species are traded on a large scale. The Mongolian oak (Quercus mongolica), for example, has a CITES protected status because it forms valuable ecosystems. But even species that are not protected, such as the English oak (Quercus robur), may only be logged in a regulated manner, because in Europe, for example, it is a component of very old natural forests.

In addition to information on species identification, information on the specific origin can also be important. This is the case when trees may be felled in certain regions or countries, but are protected in other countries. An example is the American mahogany (Swietenia macrophylla), a valuable precious wood that occurs in Central and South American natural forests. The tree species is subject to the Washington Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and may currently not be imported into the EU from Bolivia and Belize. Imports from Mexico and Guatemala, on the other hand, are permitted with the appropriate documents because sustainable management is still possible there.

Here, too, genetics is the method of choice to clarify the origin. Even if it is the same species, genetic differences have developed in the individual origins, as there is practically no exchange between the populations due to the distance. However, reference samples from the respective regions are also necessary here in order to find molecular markers in the wood DNA that are typical for the regions.

Wood is dead tissue; its DNA is subject to a constant process of degradation - it degrades. Even the DNA in freshly felled trees is already degraded, but less so than in older or treated wood. In particular, high heat and some chemicals have a strong DNA-degrading effect. This means that only small amounts of DNA can be extracted from wood and wood products - and often only in poor quality. Through our permanent method development, we are nevertheless able to extract and analyse DNA from such highly processed materials as plywood, chipboard, parquet, veneer or even wood pellets.