Forensic timber identification: It's time to integrate disciplines to combat illegal logging

Highlights

• Prosecution of illegal logging crimes is hampered by lack of forensic timber identification tools.

• A range of visual, chemical and genetic identification methods have been developed independently

• We review the use of these methods and highlight future research and development needs.

• We explore how multiple methods can be used together to answer specific identification questions.

• We call for the new integrated field of forensic timber identification to be a global investment priority.

Abstract

The prosecution of illegal logging crimes is hampered by a lack of available forensic timber identification tools, both for screening of suspect material and definitive identification of illegally sourced wood. Reputable timber traders are also struggling to police their own supply chains and comply with the growing requirement for due diligence with respect to timber origins and legality. A range of scientific methods have been developed independently with the potential to provide the required identification information, but little attention has been given to how these tools can be applied synergistically to support the legal timber trade. Here we review the use of visual identification methods (wood anatomy, dendrochronology), chemical methods (mass spectrometry, near infrared spectroscopy, stable isotopes, radio-carbon), and genetic methods (DNA barcoding, population genetics/phylogeography, DNA fingerprinting) each with potential application to forensic timber identification. We further highlight where future research and development are required to identify illegal logging crimes using these methods and suggest ways in which multiple methods can be used together to answer specific identification questions. We argue that a new integrated field of forensic timber identification should be a global investment priority, for which the ongoing collection, curation and taxonomic study of appropriate reference material is a critical part. Consideration of the specific legal requirements for method development and the application of identification methodologies to criminal evidence are also imperative to achieve robust scientific support for illegal logging crime prosecutions and prevention.

Introduction

Deforestation represents a massive threat to global biodiversity with illegal logging and the associated trade in illegally sourced wood products a significant contributor to the continuation of unsustainable deforestation rates. International efforts to combat the problem consist primarily of the enactment of laws designed to discourage the trade in illegally sourced timber, and prohibit or limit the trade of specific species or those from specific areas. Trade restrictions are imposed primarily through the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES) which lists species in one of three appendices depending on the degree of protection required. Appendix I is the most restrictive and prohibits trade in taxa threatened with extinction, trade is only permitted in exceptional circumstances; Appendix II lists species which are not currently at threat of extinction, but require controlled trade to avoid over-utilisation and future extinction threats; Appendix III lists species that are controlled in at least one country which requests assistance in trade control from other signatory countries. In addition to CITES, consumer countries increasingly prohibit the importation of any timber not obtained in accordance with the laws of the country of origin, e.g. Canadian Wild Animal and Plant Protection and Regulation of International and Interprovincial Trade Act (1992); US Lacey Act (amended 2008); EU Timber Regulation (2010); and Australian Illegal Logging Prohibition Act (2012).

Abraham Lincoln once said “Law without enforcement is just good advice” and currently this is the status quo in most parts of the world with regards to illegal logging legislation. With the best of intentions, law makers have set enforcement officers an impossible task; to seize illegal wood products and prosecute illegal logging crimes, without in most cases the means to identify timber to a level of certainty acceptable for admission to a court of law. The push for more sustainable forestry practises also comes from within the industry, with reputable traders eager to comply with new laws, but similarly facing the daunting task of policing their own supply chains without the scientific tools to independently verify the origin of their wood products. One of the key problems is that timber products do not generally possess the diagnostic features required for plant identification (i.e. the leaves, flowers and fruits of the tree) and hence reliable identification is extremely challenging. Identification questions most often begin with the taxonomic identity of a product (i.e. from which genera or species does the timber originate?). Questions of geographic region of origin often follow as some species are only trade-restricted from certain areas of their distributional range but not others (e.g. some species listed in CITES Appendix III). In this context, ‘region’ refers to a specific geographic area, which may or may not be synonymous with a country or recognised subdivision within. The age of a specimen can also be important, as timber harvested prior to legislation is often exempt. Finally individual identification is sometimes sought, to link timber products to the original tree, either as part of supply chain verification systems or to identify theft.

Several separate scientific disciplines have turned their attention to the problem of timber identification (Table 1, Table 2); the most established of these is the study of wood anatomy — which provides taxonomic characterisation based on the internal structure of timbers. Other identification methods include various forms of visual, chemical and genetic analysis. However, these methods vary quite considerably in terms of the granularity of identification that is afforded, which is also dependent on taxonomic group. In addition, the prior information required and the cost of analysis also varies widely (Table 1, Table 2). Due to the disparate nature of the various disciplines, and the relative infancy of many of the specific identification techniques, there has been very little synthetic work to date which seeks to assess the current state of the art (but see Wiedenhoeft and Baas, 2011).

Methods for tracking timber based on non-inherent features of wood are currently the most commonly used and can provide complementary information to assist with illegal timber investigations. These methods include simple measures such as the use of painted identification marks and paper based certificates but also range to more sophisticated measures that present significant problems for those seeking to commit fraud, such as the use of physical barcoding tagging systems and radio frequency identification (RFID) tags (Seidel et al., 2012). However, for forensic diagnostic timber identification, only those methods which rely only on inherent wood characteristics (such as anatomy, chemistry and genetics) can provide reliable identification outcomes to support the law; it is these specific methodologies that are the subject of the current paper.

Here we review the various scientific methodologies that have potential for use as forensic timber identification tools and consider how multiple approaches could be integrated to answer a range of identification questions. Our treatment of each approach is necessarily brief, but intended to provide an overview and direct the reader to more in-depth material where desired. We also explore some of the issues pertinent to all identification methods, such as the availability and taxonomic integrity of reference material, and the steps required to take academic research into the forensic arena.

Timber identification was historically a branch of wood technology, but is now generally considered to be part of the broad fields of wildlife forensics and forensic botany. However, wildlife forensics focuses almost exclusively on animals, and forensic botany on the use of plant identification to solve crimes, usually where traces of plant material are found at the scene of a crime and can be used to link back to the perpetrators. Forensic botany rarely focusses on illegal logging, in which the trees themselves are the victims of criminal activity. This gap between policy requirement and scientific application has been highlighted by a recently convened expert working group on the subject, brought together by the United Nations Office of Drugs and Crime (UNODC). Given the scale of illegal logging and urgent need for practical timber identification solutions, we contend that the interdisciplinary field of forensic timber identification should be established as a specific research and investment priority.