Résumé
Diversification of cropping systems is a strategy to increase their social and ecological resilience and delivery of ecosystem services. Such practices are prevalent in traditional agroforestry systems, such as those where coffee (Coffea arabica) is grown. Indeed, though they face several challenges, Haitian coffee agroforestry systems are important contributors to rural biodiversity and household livelihoods. However, little scientific attention has been paid to these systems. We studied diverse farms in historically important coffee growing regions of northern and southern Haiti and characterized the diversity of several components of their agroforestry systems: coffee plants, shade trees, and associate crops. We tested the relationships between these different levels of diversity and identified key ecosystem services delivered by them, including provision of diversified farm products and carbon storage. In the case of Arabica coffee specifically (Millet et al. 2023), using targeted genotyping, we found significant genetic diversity and complex varietal mixtures. We show that some coffee farms are repositories of historical, widely-abandoned varieties while others are generators of new diversity through genetic mixing despite Arabica's tendency towards autogamy. In the latter, several varieties are often grown together, often in an uncontrolled manner, and are allowed to crossbreed with recruitment from the seed bank common, explaining the frequent admixture detected. Comparing these results with local, vernacular identifications, we found that the diversity in these systems is often under-estimated. These studies are, to our knowledge, the first to genetically characterize Haitian C. arabica and one of very few that have looked at Haitian agroforestry system crop and tree diversity.