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End-product test analysis
DNA and stable isotopes allow for testing products off the shelf. By testing the product at the end of a supply chain, you are measuring the effectiveness of the traceability measures put into place in that particular supply chain.
Robust forensic methodologies
DNA and stable isotope analysis are both time-tested forensic methods. Evidence from both methods has been used extensively in court cases.
What DNA tells you about the origin of timber:
In simple terms, DNA analysis of timber is an investigation into the genetic lineage of timber. This is not directly related to the origin of the timber, but is very well correlated with it.
What stable isotopes tell you about the origin of timber:
Stable isotope analysis is an investigation into the origins of the elements that make up the timber. The stable isotope ratios in a piece of timber are directly related to where the piece of timber originated from.
How reference data is used across different species
Stable isotope analysis is a comparative technology, in order to verify origin a test sample must be compared to a database of known reference samples. The isotope ratios of hydrogen, oxygen and carbon in timber are related to the species of timber as they are linked with water balance and photosynthetic pathway. Conversely, geologically related isotopes such as nitrogen, sulfur and strontium are independent from species and can be used broadly to authenticate the origin of timber.
Both DNA (Genomic) analysis and stable isotope analysis have desirable advantages over paper-based traceability methods, here’s a quick summary of what they have in common and where they differ.
Country of origin of timber is currently verified by shipping and other supply chain documentation, rather than by independent inspection - a process that is considered by WWF to be an "important loophole" in the traceability of timber.
To combat the illegal trade in timber an end-product test is necessary to show analytically whether timber is or isn't from its declared origin. Rather than attempting to re-trace timber back to its origin using traceability records or mass-balance, isotope testing looks at whether a tested sample of timber matches its declared origin.
Isotope testing is recognised by WWF as an important tool to fight the illegal timber trade and provide supporting evidence of legitimate trade.
Though the demand for technology to authenticate the country of origin of timber is growing and has recently seen expansion in the Global Timber Tracking Network (GTTN) project.
Agroisolab currently has access to reference data for:
With databases continually growing as the demand to protect forests and the authenticity of timber products increases.
As mislabelling in timber comes in many incarnations, Agroisolab work with a network of laboratories in order to deliver a complete suite of authentication work. Confirmation of geographical origin and species of timber is often necessary, if you would like to discuss the needs of your project, we will be happy to help.
Results of the GTTN project - Stable Isotopes vs. DNA
As part of GTTN project, an assessment of stable isotope analysis and genomic (DNA) was perfromed as a blind test. Samples were submitted to each participating laboratory, the task was to identify whether any of the blind samples were likely to be 'fraud' samples (samples not from their delcared country of origin). The results demonstrated that stable isotope analysis currently offers the leading solution to determine the origin of timber as it was able to identify more of the 'fraud' samples than genomic analyses. However, it is considered that combining the two technologies may provide an even more effective solution that using them independently.
Water isotope ratios in timber
Water plays an essential role in determining the origin of timber. The isotope ratios of hydrogen and oxygen from precipitation (rain) are primarily dependent on the annual temperature of a location and, to a lesser degree, are influenced by altitude, latitude and the ‘continental effect’. Regional provenance can be determined by D/H and 18O/16O isotope ratios.
Carbon isotope ratios in timber
Carbon ratios are primarily dictated by the photosynthetic pathway the tree uses (CAMS, C3 or C4). There is strong fractionation of carbon ratios dependent on stomata conductance and photosynthetic assimilation; both are influenced by environmental factors such as humidity, light and temperature. Therefore, the carbon ratios in timber are reflective of the local climate.
Geological stable isotopes in timber
Geological isotopes can vary dramatically within a country as they reflect the local geology of the soil unlike wide scale patterns such as water isotopes (D/H and 18O/16O). This is due to the fact that they primarily reflect local geological and chemical cycling (15N/14N, 34S/32S). Secondarily isotope ratios of nitrogen and sulphur may reflect ‘fall-out’ effects which may follow a wider pattern.
18O/16O (oxygen) isotope ratios in Iroko (Milicia excelsa) timber across Africa. Click to expand.
15N/14N (nitrogen) isotope ratios in Iroko (Milicia excelsa) timber across Africa. Click to expand.
13C/12C (carbon) isotope ratios in Iroko (Milicia excelsa) timber across Africa. Click to expand.