Multi-element analysis has the potential to be developed into a timber tracing tool to help combat illegal trade. That’s the conclusion of a recent project undertaken by an international group of researchers who collaborate via Timtrace, a Dutch-based operation that develops and tests methods to verify the claimed origins of timber.
The Timtrace report says that tracing has become more important than ever, as regulation internationally seeks to ensure timber trade legality to combat deforestation. “Legislation, such as the EU Timber Regulation (EUTR) and the incoming EU Deforestation Regulation (EUDR) require documents and certificates of origin. Yet, these can be falsified. Therefore, it is important to independently verify the origin of wood, based on the properties of the material”, states Timtrace. “These methods can help timber traders to support the paper trail showing they source timber legally and create transparency in their value chain.”
Multi-element analysis, says the research project report, involves measuring a large number of elements, such as magnesium, calcium, and lanthanum, simultaneously using mass spectrometry. Based on this elemental analysis, an ‘origin-specific fingerprint’ is defined given that the chemical composition of plant material, such as wood, varies according to local environment and soil chemistry. The most likely origin of a sample can be determined by comparing the chemical fingerprint to an established geo-referenced dataset.
“This can help to answer two relevant tracing questions: origin verification and assignment”, says the report. “The verification question addresses whether a wood sample came from a certain (claimed) origin. The assignment question addresses which location a wood sample most likely originated from in case the sample origin is entirely unknown.”
Multi-element analysis has been shown to work for the assignment and verification of a range of commodities, including vegetables, bananas, and tea. However, the chemical composition of timber is more complex and the method had not previously been tested sufficiently across different countries and wood species. The research project looked at its applicability to three economically important species, tali and azobe from Central Africa and red meranti from Borneo.
“We first analysed whether the two timber species from Central Africa shared their variation in elemental composition across the study region”, says the project report. “Then we developed classification models for all timber species based on the elemental composition, addressing both origin verification and assignment accuracy.” The researchers assessed whether wood elemental composition correlated with soil variables that affect element uptake and lastly simulated a real-life tracing case by applying classification models to a set of blind samples, to determine their most likely origin.
In Central Africa, tracing accuracy was 86%–98% for regional clusters of chemically similar sites, with accuracy depending on the tracing question. These clusters were 50–800 km apart and tracing accuracy was highest when combining the two timbers. The tracing accuracy of Red Meranti on Borneo was 88% at site level. The researchers state that further evaluation in the use of this approach with wood is needed, with reference databases covering wider geographic areas and representing more species. But their first project results are considered a success. “Overall, these results illustrate a high potential for multi-element analysis to be developed into a timber tracing tool which can identify the origin for multiple species and can do so at a within-country scale”, concludes their report.