Using Chemical Fingerprints to Fight Illegal Logging

Lumber has been in the news lately because of the U.S. Department of Commerce ruling on Softwood Lumber from Canada. A recent research paper proposes forensic chemical analysis to solve another problem plaguing the lumber industry: illegal logging.

Douglas-fir has well contrasted earlywood (light colored cells) and latewood (dark colored cells) in its annual rings. (Source: ScienceDaily/Edgard Espinoza)According to the World Wildlife Fund, the global illegal lumber trade is estimated by the United Nations “at between $30 billion and $100 billion annually,” robbing both developing countries, where the bulk of timber is illegally harvested, and lowering the market price of lawfully harvested wood. In the U.S., “the wood products industry loses as much as $1 billion annually from illegal logging.

Imported wood requires documentation citing its species and geographic origin to make sure it complies with the endangered species protections, more specifically the Lacey Act and terms set out by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITIES). Unfortunately, this paperwork is often forged or inaccurate. It is possible to verify species with a microscope, but geographic origin is much more difficult to confirm.

Dots show the site of sampled trees in Oregon, U.S., with Cascade Range samples in red and Coast Range samples in blue. (Source: Botanical Society of America/Cronn)

A group of researchers, led by Dr. Richard Cronn of the Pacific Northwest Research Station of the USDA Forest Service, discovered how to pinpoint a much smaller region of geographic origin than previously documented. The team used chemical fingerprinting techniques to measure compounds in Douglas-fir (Pseudotsuga menziesii) samples.

Within construction, Douglas-fir is known as one of the stronger and more durable softwoods available. Within the realm of dendrochronology and historical climate studies, it is appreciated for its well-defined annual rings that make it easy to count its age.

The team used direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS) to measure the chemical makeup of tiny wood samples of Douglas-fir trees from two mountain ranges. Almost 950 molecules were detected in the wood, creating chemical fingerprints.

The researchers compared these molecular differences in 188 trees, allowing them to identify the trees's region — either the Oregon Coast or Cascade range — with a 70 to 76 percent accuracy. The success rate is significant; unfortunately, the researchers are not entirely sure why these changes occur.

Some of the molecular compounds analyzed could be identified by comparing their profiles to a database of other conifer tree species. Others could not. Cronn is not prepared to give up on discovering the source of these geographic changes. They are currently investigating whether the differences in molecular compounds arise from genetic differences between the populations, environmental differences, or a combination of the two.

“Douglas-fir may be the most important structural timber tree in North America,” Cronn says, “but we still have much to learn about its wood chemistry.”