Stable isotope ratio analysis to determine the geographical origin of timber: A review

Illegal logging represents a significant threat to forest ecosystems and their biodiversity. A robust method for tracing the geographical origin of timber allows to verify whether the timber comes from legal sources. A strong candidate is stable isotope ratio analysis, as isotopic ratios vary spatially according to environmental and climatic variables among others. Here, we present a review on H, C, O, N, S and Sr isotope ratios to determine the geographical origin of wood and its components. δ(¹³C) is a good proxy for determining timber provenance on a large scale. δ(¹⁸O) and δ(²H) are strong spatial predictors and generally exhibit altitude and continental effects. δ(¹⁵N), δ(³⁴S) and δ(⁸⁷Sr) are effective for local-scale traceability but less suitable for larger-scale applications. Isoscapes represent a powerful tool for estimating the isotope values of timber across a large spatial range. Advances in methods standardisation, databases and modeling will improve effectiveness, supporting global regulations to protect forests.