DNA based methods leave illegal loggers with no place to hide

Could DNA-based prevention efforts spell trouble for illegal loggers? jimmedia

Illegal logging is a major contributor to tropical deforestation and forest degradation. Australia is currently considering legislation to prevent the importation of illegally logged wood. But if the legislation passes, we will still face the problem of identifying the origin of imported timber. DNA-based technology could be the solution.

Legislation has been introduced in the US and the EU to limit the importation of timber from non-certified or illegal sources.

Some of this legislation now has real teeth. Guitar manufacturer Gibson fell foul of the US legislation when Madagascan Rosewood was discovered at one of their warehouses. Whilst not prosecuted criminally, the US Government reached a criminal enforcement agreement with Gibson, who admitted the company was in contravention of the Lacey Act in using the CITES trade-restricted species.

Gibson were required to pay a penalty of $300,000, as well as $50,000 to the National Fish and Wildlife Foundation to be used “to promote the conservation, identification and propagation of protected tree species used in the musical instrument industry and the forests where those species are found.”

The case received broad coverage and is widely referenced. It gave a clear message that the government means business when it comes to illegal logging.

So how can we be sure our timber comes from a legal source? Credible voluntary certification such as the Forest Stewardship Council (FSC) is one such way. “Chain-of-Custody” methods are also commonly used. They seek to assign a paper identification to individual logs so they can be tracked along the timber supply chain. However these “paper passports” are open to falsification, particularly between the logging concession and mill where most illegally logged timber is introduced into the supply chain.

Fortunately there are a number of methods that can be applied to verify source claims. The most promising are from a suite of DNA-based methods: DNA fingerprinting, genographic analysis and DNA barcoding.

The Gibson Guitar settlement struck a chord with wood companies. Vitor Bellote

Species identification and DNA barcoding

DNA barcoding is a global initiative designed to standardise species identification by analysing short DNA sequences. The standards developed have seen more than a quarter of a million species DNA barcoded.

One of the biggest challenges for this method has been identifying a gene region that can reliably differentiate between species. In 2009, the CBOL Plant Working Group finally recommended a combination of two chloroplast genes, maturase K (matK) and ribulose-bisphosphate carboxylase (rbcL). Between them they can distinguish approximately 70% of all plant species, although more in some field applications.

If further species resolution is required, “local” barcodes can be developed. For example, a set of local barcodes were developed to differentiate between the three species of Central American mahogany, when the standard barcode genes failed to tell them apart.

A DNA barcoding approach would have been able to identify that the wood sourced by Gibson Guitar came from a trade-restricted species.

Lowe AJ, Cross HB (2011) The Application of DNA to Timber Tracking and Origin Verification. Journal of the International Association of Wood Anatomists 32(2): 251-262.)

Source origin and genographic mapping

For many species protected under the Convention on International Trade in Endangered Species CITES, identifying country of harvest is critical to determining the legality of timber. Sourcing the timber through its DNA requires us to assess the genetic variation that is structured across natural populations of a species. This variation arises due to differences in geological history, climate and soils, seed and pollen dispersal and local selection pressures. These interactions will produce genetic discontinuities that can be mapped.

In a nice early example of the power of such methods, an angler was disqualified from a fishing competition when tests on the fish he presented identified that it could not have come from the river where the competition took place. When presented with this evidence, the angler confessed he had purchased the winning fish from a local market.

For timber, a blind test of mahogany organised by the World Wildlife Fund for Nature (WWF) correctly assigned wood samples to a Bolivian or Guatemalan source with a high degree of certainty.

Individual tracking and DNA fingerprinting

DNA fingerprinting, similar to that used in human forensics cases, has been applied commercially for several years to track timber logs along supply chains.

In a study of merbau (Intsia palembanica), a high-value timber species from southeast Asia used primarily for decking, DNA fingerprinting was used to compare samples of timber from a saw mill in Java, Indonesia, with their declared forest source. In this test, all mill samples could be positively identified as coming from their declared forest concession. It was good news for Simmonds Timber, who use this supply chain and market their DNA-verified product as “DNA lumber.”

One of the key problems with applying genetic tests to wood is actually extracting DNA from test samples in the first place. However, using contamination-exclusion techniques similar to those developed to work on ancient sources, the potential is growing for routine genetic analysis from timber.

The advancement of genetic technologies means that large-scale DNA screening is now done cheaply and quickly. Most importantly it can be conducted with statistical certainty sufficient for legal cases.

This means there are an increasingly powerful array of methods that provide the consumer with a verifiable confirmation of the declared source of origin of timber products. This allows them to actively choose timber products that aren’t illegally sourced and don’t contribute to the global deforestation crisis.