Development and application of genetic timber tracking tools to help control illegal logging

Abstract

Illegal logging of timber is a significant problem worldwide. Apart from being a major driver of global deforestation, there are also severe economic implications. To abet the illegal trade, timber is often laundered into otherwise legitimate systems, tainting the supply chain, and sold on to unwitting consumers. Attempts to control and monitor the trade of illegal goods have been made by some of the major timber importing nations, with laws enacted that require importers to provide evidence of the species of timber and where it comes from. There are several scientific methods suitable for ascertaining this information from the timber itself; furthermore, these approaches can be used retrospectively by government agencies to assess the veracity of the declared claims. This thesis focuses on the application of genetic methods for the monitoring and control of traded timber. Genetic methods have been used for identification purposes in many other species, most notably humans. Furthermore, they were recently recognised as being suitable for timber species in UNODC guidelines on forensic timber identification. Yet difficulties associated with obtaining DNA from timber material are holding back the uptake of genetic methods in timber identification. Compared to fresh leaf tissue, extracting DNA of sufficient quality and quantity from timber is not routine. This is a critical limitation, as without the capacity to extract DNA from timber, genetic techniques cannot be used effectively for supporting legislation. Additionally, for most timber species, there are currently no species-specific genetic markers that can be used for origin verification or individualisation tests available. Even for species where markers do exist, there is generally a lack of research concerning how well these approaches perform and the best way they can be utilised within a legal context. My thesis presents work that was conducted as part of a patent application for extracting DNA from timber and other degraded plant material. It then focuses on the development of species-specific genetic markers for two timber species; bigleaf maple (Acer macrophyllum) and ayous (Triplochiton scleroxylon). Ayous markers were used to conduct a population genetic analysis to identify the genetic structuring of the species across its native range. The results from that analysis were then incorporated into an assignment testing study, which was used to assess the claimed origins of blind test samples. The blind testing results were used to determine the effectiveness of the genetic markers and analysis approach to verify traded timber of ayous. The DNA extraction project identified optimum conditions for successful extraction using our developed method, and the outcome was then compared to commercial kits. The patented protocol performed as well as the commercial kits and was often successful where the kits failed. The marker development studies were successful, and variable markers were developed for both species. For ayous, the population genetic analysis identified three genetic populations across its natural range in tropical Africa. In addition to supporting previously identified patterns of genetic structure in the region, this work has furthered our understanding of the region’s biogeography by identifying a novel genetic boundary occurring between the northwest and central samples from the Democratic Republic of the Congo (DRC). Samples from central DRC formed an isolated genetic group, while samples from the northwest of the country were more closely related genetically to samples from Cameroon and the Republic of the Congo. The study identified that the genetic patterns of ayous have likely been driven by geneflow and impacted by the contraction and expansion of forest boundaries in recent geological history. The subsequent assignment testing found that assigning to the three genetic groups was the most successful approach, with lower success when assignment was based on country of origin. However as long as appropriate assessments were made to determine the significance of assignments, then acceptable results for country level claims were also achieved. Unfortunately, in ayous there is insufficient support in the data to perform origin assessments at the geographical population level. In conclusion, this thesis demonstrates the capacity for using genetic methods to identify timber material. Furthermore, these methods are highly suitable for supporting law enforcement efforts to control and monitor the timber trade. Techniques that are underpinned by a scientific framework, such as genetics, can provide the certainty needed to meet legal requirements. Appropriate application of these techniques can assist measures to reduce the incentive for illegal logging practices; and promote the trade of legitimate products. Measures such as these can contribute to diminishing the negative environmental and socioeconomic impacts of illegal logging.