Tropical timber tracing and stable isotopes : A response to Horacek et al.

Abstract We appreciate the comments of Horacek et al. on our publication about African timber tracing (Vlam et al., 2018). In short, our results showed that the geographic origin of Tali timber could be inferred from genetic characteristics (DNA), but not from chemical characteristics obtained from measurements of 3 stable isotopes. Horacek et al. claim that the latter result was due to project design and not to the isotopic method. While we acknowledge some of advices by Horacek et al., our study design was well suitable to test the application of stable isotopes. It just did not work for the isotopes studied – carbon, oxygen and nitrogen – and at the small geographic ranges included in our study. Our results do not support, nor do we want to suggest, the conclusion that stable isotopes are not useful to perform timber tracing. Rather, we have shown for this species and at the sampled forest concessions, that stable isotopes of carbon oxygen and nitrogen do not allow differentiation and therefore offer no potential for chemical tracing.