Restoration of Vanuatu sandalwood (Santalum austrocaledonicum) through participatory domestication

Abstract

ABSTRACT Sandalwood (Santalum austrocaledonicum) is a fragrant tree of cultural and commercial importance in Vanuatu. The trade in its wild products has long provided income to landowners on remote islands. Due to unmanaged harvesting, however, wild sources of sandalwood in Vanuatu have declined in recent years. Domestication of the species and deployment of improved germplasm through smallholders can facilitate its restoration through circa situm plantings. Recognising the need to transition from wild harvest, landowners have commenced planting the species in home gardens and using it to enrich agricultural fallows and natural vegetation. Improvement of sandalwood through domestication has the potential to increase tree productivity, heartwood volumes and heartwood oil quality. This can enhance income and livelihood benefits associated with smallholder-planted sandalwood in Vanuatu. This paper outlines a strategy for participatory domestication to ensure that improved sandalwood germplasm is available for domestic sandalwood growers. The amount of the oil-bearing heartwood determines the commercial value of individual trees, which is linked to growth rates, heartwood oil concentration and chemical composition. There is substantial tree-to-tree and provenance-based variation in all these characteristics on which to base its domestication. The domestication strategy has been developed with consideration of the resources and capacities of stakeholders in Vanuatu. It is based on conventional approaches to plant improvement and the engagement of landowners to enhance germplasm deployment and manage institutional and environmental risk. The current breeding population comprises a grafted clonal archive of 39 genotypes selected from more than 250 wild trees sampled throughout the country. These genotypes were selected for their elevated levels of key oil components α- and β-santalol across seven island provenances. This breeding population has been deployed successfully as small clonal seed orchards on seven islands (Santo, Pentecost, Malekula, Ambrym, Epi, Efate and Tanna) to provide improved seed where it is needed most. The genetic base of established orchards will be expanded by introducing new selections from planted and wild populations in a ‘rolling front’ breeding strategy, as described in this paper. Families in the breeding population will be tested in progeny trials on participating islands to assess their genetic performance and retention in seed orchards, with later conversion to seedling seed orchards. The participatory approach to domestication and the deployment of germplasm provides a sound genetic foundation for landowner-driven sandalwood restoration in Vanuatu.