Appliance of wood identity science

There has never been more onus on the timber trade to prove where its wood comes from and what species it is.

A growing percentage of customers and specifiers want to know timber is sustainably sourced. Market legality requirements, such as the EU Timber Regulation, also demand companies practise due diligence to ensure it’s legally harvested.

That’s good news for the forest and environment, but added pressure for the timber trade. However, there are now increasingly effective scientific methods for verifying supplier claims on wood type and origin.

The classic route is to use macro- and microscopic wood anatomy analysis, based on visual examination of specific timber features. The macroscopic approach comprises unaided eye, or hand lens examination. This is quick but limited to solid wood and identifying species groups.

Microscopic identification uses a light microscope to compare small anatomical wood structures. This probes down to genus, or sometimes sub-genus level, and was used by the UK EUTR Competent Authority in its Chinese plywood investigation, identifying that species claims for nine out of 13 samples were wrong. The method can be used for solid wood and some composite products, but not yet those where identification elements are very small, or wood is chemically or physically altered.

Among newer identification methods, DNA analysis compares genetic sequences to determine species, with trees that are more closely related having more similar sequences. In 2011, German customs seized timber after DNA analysis proved wood samples were a CITES-listed species, rather than a related non-listed type.

DNA analysis can also sometimes identify timber’s geographic origin and be used for log identification to aid chain of custody assessment.

The method is expensive, so generally reserved for more valuable timber, but it can additionally be employed where harvest permits record GPS location or tagged tree stump.

At the timber testing cutting edge, stable isotope analysis verifies origin by comparing ratios of common elements within timber samples, such as carbon, hydrogen, oxygen and nitrogen. Trees growing in the same area will take up similar ratios, so have similar isotope signatures.

While this method has only relatively recently been applied to timber, it is already proven in identifying provenance of food; from eggs, wine, beef and fish to caviar!

It was also employed by the WWF’s 2015 ‘Forests Campaign’ to test timber products from UK companies. This showed that eight out of 26 samples contained wood from a different origin to that declared by suppliers.

So there are increasing and increasingly accurate options for identifying your wood. That’s good for the forests – and your business.