Multi-isotopic Provenancing: Forensic Analysis for Determining Geographic Origin of Sandalwood

Previous overharvest and poor management of sandalwood has depleted wild populations and remaining wild sandalwood is under further pressure from illegal logging. Laws and regulations to control harvest of sandalwood in Australia have increased but cannot be enforced without tools to independently verify sandalwood sources. Multi-isotopic provenancing is an emerging tool for determining geographic origin of natural products that could be applied to detect illegal trade of sandalwood. This thesis aims to identify and address current gaps in knowledge related to timber tracking for sandalwood and develop multi-isotopic provenancing for independent verification of geographic origin of sandalwood. The importance of sandalwood and immediate need for tools to trace sandalwood sources is established in a review of sandalwood history, use, management and tools for timber tracking (Chapter 2). Sandalwood’s extensive history of cultural, medicinal and economic value is highlighted, followed by a brief summary of the sandalwood market, conservation challenges (including illegal logging), management strategies and regulations. An examination of current and developing tools for timber tracking demonstrates the need for methods to determine geographic origin of sandalwood. Isotopic variation within an individual sandalwood tree is characterised (Chapter 3) to addresses several key questions relating to reference sample requirements for timber provenancing. Carbon and oxygen (δ13C and δ18O) isotopic analysis of sandalwood leaves, branches and stem wood show leaves are significantly different isotopic composition to branch and stem wood. Branch wood is significantly different to stem wood in δ18O but not δ13C. A minimum sample size of 5cm for wood samples is recommended to provide a sample representative of the whole core value. Findings here also supports the use of bulk isotope analysis of woody tissues rather than cellulose. Multi-isotopic (δ13C, δ18O and 87Sr/ 86Sr) signatures of sandalwood from eight sites in Australia and one site in China are analysed to determine the utility of isotope analysis for differentiating between sandalwood sources on different spatial scales (Chapter 4). Isotopic signatures in sandalwood are significantly different between sandalwood from different countries and are distinct between sandalwood from sites within the same region. Isotope variation between sandalwood sites relates to annual rainfall (δ13C and δ18O) and underlying/adjacent geology (87Sr/ 86Sr). Results suggest that multi-isotopic (δ13C, δ18O, 87Sr/ 86Sr) provenancing in sandalwood can be used to distinguish between different geographic origins. A case study demonstrates multi-isotopic provenancing for the independent verification of sandalwood geographic origin in a real-world setting (Chapter 5). Multi-isotopic provenancing showed sandalwood of unknown origin to be inconsistent with their designated origin and identified a reference location with consistent isotope chemistry to the unknown samples. Together this work presents a compelling demonstration of the utility of isotopic provenancing for sandalwood timber tracking.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 202

Safeguarding sandalwood: A review of current and emerging tools to support sustainable and legal forestry

Societal Impact Statement: Sandalwood and other high value tree species are under significant threat from illegal harvest. Illegal logging is an increasing problem contributing to deforestation, biodiversity loss, human rights abuses and funding transnational crime. Successful prosecution of illegal logging is hindered by a lack of methods to provide evidence of the origin of timber. New analytical techniques have been developed to trace timber back to its source. These methods, together with the establishment of sustainable sources of forest resources, can help protect vulnerable species by providing evidence to prosecute illegal harvest and ensure that commercially available forest products come from sustainable sources. Summary: Sandalwood is highly valued for its fragrant oil and has a long history of cultural and economic importance in many regions of the world. Historical overharvest and poor management have depleted natural populations of sandalwood, which are slow to regenerate. The increasing establishment of plantation sandalwood creates an alternative resource for the sandalwood industry while potentially relieving harvesting pressure on natural stands. Due to the high demand for sandalwood, remaining wild populations are still under threat from illegal logging and methods to identify the source of harvested sandalwood are needed. Laws and regulations aimed at preventing illegal harvest and possession of sandalwood have been put in place but cannot be enforced without the forensic tools to independently verify claimed origin or product quality. The high value of sandalwood combined with the difficulties in enforcing illegal logging laws makes these species particularly vulnerable to poaching. There is an immediate need to develop tools that can identify illegally sourced and adulterated sandalwood products. This paper reviews the current and developing scientific tools that can help identify and control illegal activity in sandalwood supply chains and provides recommendations for future research. Topics include isotope and DNA analysis for tracing illegally harvested sandalwood, chemical profiling for quality control of sandalwood oils, network and policy development to establish a framework for future regulation of the sandalwood trade