Â鶹ÒùÔº

By combining chemical and genetic properties of wood, the origin of tropical hardwood can be determined much more accurately. This precision is needed to detect illegal timber trade. This is the main outcome of a study by Wageningen University & Research and international partners. The researchers determined the chemical and genetic properties of nearly 250 trees from Central Africa. By combining wood properties, they were able to estimate the origin of those trees with 94% accuracy within a radius of 100 km.

Illegal timber trade is a widespread and lucrative form of crime, often involving falsified origin documents. In several African countries in the Congo Basin, it is estimated that up to 90% of exported timber is traded illegally. To counter this fraud, the EU has adopted the European Deforestation Regulation. The legislation will require timber traders—by the end of 2025 or 2026—to prove that their products have been obtained legally, and are not sourced from recently deforested areas.

Laura Boeschoten, Ph.D. graduate at Wageningen University & Research and one of the lead authors of the in Communications Earth & Environment, explains, "This legislation requires that the exact origin of wood be reported when it enters the European market. But because of frequent fraud, authorities must also be able to independently verify the origin. For example, by analyzing wood properties. Our research shows that this verification can be highly accurate when different wood properties are combined."

Blind spots

The team studied the African timber species Azobé, which is widely used for hydraulic engineering projects. They measured concentrations of a large number of chemical elements in the wood (such as magnesium and calcium). These values are determined by the soil type where a tree grows. They also measured other chemical wood characteristics that reflect regional climate. Finally, they examined genetic properties, which differ more strongly the farther apart trees are located.

Using these properties, the team estimated the wood's origin. Based on just one of the three techniques, the likelihood of correctly estimating the origin within 100 km ranged from 50–80%. Combining the techniques yielded a much higher score: 94%.

Barbara Rocha Venâncio Meyer-Sand, researcher at Wageningen University & Research and also one of the lead authors, explains, "Some wood properties are determined by conditions that differ only across large distances. Others vary more strongly between trees that grow close to each other. By combining them, the blind spots of one technique are compensated by the other two."

The power of collaboration

Combining techniques for origin determination is still in its infancy. Research leader Pieter Zuidema, professor at Wageningen University & Research, says, "In recent decades, researchers have mainly focused on developing and promoting their own technique. We take a different approach: we compare and combine them. Of course, combining is costly and will in practice only be used for very valuable timber species or when risk of illegality is very high."

The study results from intensive collaboration with researchers in the Congo Basin. Rocha Venâncio Meyer-Sand says, "We provided training to them, conducted joint fieldwork and shared responsibilities. We truly achieved these results together."