Development of species distribution models helps identify source country anomalies in timber supply chains

Abstract For many timber species, a lack of consistent, comprehensive global distribution data makes validating supply source (country of harvest) difficult. To supplement these data, we developed species distribution models (SDMs) for the American mahogany species (genus Swietenia ) to demonstrate how SDMs can assist in the analysis of supply sources by comparing SDM predictions against Swietenia product import declarations. A declared harvest country may appear inaccurate due to merely a lack of distribution data, declaration of a Swietenia species in place of the true species, or declaration of a manufacturing country in place of the harvest country, which could occur with value‐added products with potentially longer supply chains, such as furniture or musical instruments. By assessing the climatic suitability of declared harvest countries, SDMs can help determine whether the country is a plausible source for the species. We created SDMs using presence‐absence and presence‐only occurrence data for the three Swietenia species. We then compared our range map predictions and the known range countries of Swietenia species to a set of US import declarations of Swietenia species. Each declared species‐country pair was classified as confirmed or unconfirmed based on the known range countries, and suitable or unsuitable based on the model output. By examining the unconfirmed, but climatically suitable, species‐country pairs, we identified new range countries for Swietenia species, which were poorly documented in the literature. Most declarations with unconfirmed harvest countries showed risk of being look‐alike species inaccurately declared as Swietenia species. Finally, value‐added products did not have unconfirmed countries of harvest at higher rates than rawer wood products, which would occur if manufacturing versus harvest countries were declared. From these results we conclude that inadequate range data and supply chain complexity contribute to some, but not most declarations of unconfirmed countries of harvest for Swietenia products. Our results show how SDMs can expand knowledge of a species' global range and help identify risk factors in trade. While we focused on US imports of Swietenia , our methods could be applied to any species or regulatory framework where knowing the country of harvest is necessary.