Combining wood anatomy and chemical fingerprinting maximizes tropical timber identification success

Abstract

Key message
A combination approach to wood identification methods yields superior results when identifying timber originating from the Central African tropics. This is demonstrated by the performance of DART-TOFMS as a fine-tuning step after the microscopic analysis of wood anatomy. These identifications reveal species misdeclarations in small-scale timber markets in the Democratic Republic of the Congo with detrimental ecological and socio-economic effects.

Context
Identifying timber helps enforce international timber regulations. Both the conventional method of microscopic analysis of wood anatomy and chemical fingerprinting using Direct Analysis in Real-Time – Time-of-Flight Mass Spectrometry (DART-TOFMS) face challenges that make identifications difficult, especially in the central African tropics. Meanwhile, these methods are of immense value to help monitor forest exploitation and screen species declarations on the pivotal small-scale timber markets of the Democratic Republic of the Congo (DRC).

Aims
We evaluated the performance of both wood anatomy and chemical fingerprinting to identify timber traded on local markets in the DRC and quantified the misdeclarations uncovered through these methods.

Methods
We examined wood anatomy using light microscopy and performed chemical fingerprinting using DART-TOFMS for 115 timber samples originating from local markets in Kisangani, DRC.

Results
Microscopic analysis of wood anatomy performed better than DART-TOFMS (41 vs. 32 species identifications), but the performance can be improved significantly by combining both techniques (56 species identifications). Our identifications revealed that 26 samples were mislabelled.

Conclusion
We recommend expanding the DART-TOFMS reference databases and recognizing the power of combining established and emerging identification methods. This will help expose misdeclarations in timber markets and ultimately halt the illegal timber trade.