• Who are we?
  • In a nutshell
  • Our mandate
  • Our strategy
  • Our partnerships
  • CIRAD worldwide
  • Our values
• Research operations
  • Priority lines of research
  • Research Topics
  • Supply chains
  • Research units
  • Collective research tools
  • Research results
• Teaching & training
  • PhD training
  • Higher education
  • Available training
  • Offre de formation
  • Scientific experience
  • E-learning
  • Grants
• Innovation & expertise
  • Partnerships for innovation
  • Skills and expertise
  • Products and services
  • Technology transfer
  • The CIRAD VIP newsletter
• Publications & resources
  • Documentary resources
  • Publications
  • Science for all
  • Website Directory
  • Vidéos

In Vanuatu, a volcanic archipelago in the South Pacific, root and tuber crops ensure the subsistence and self-sufficiency of the islands' inhabitants. Be they taro (Colocasia esculenta) or the greater yam Dioscorea alata , which are traditional crops introduced by the first sailors to have travelled to the islands some 3500 years ago, or other plants that have been grown for some time or were introduced more recently, root and tuber crops, which are propagated vegetatively, replanted and propagated by cuttings, are the mainstay of the Melanesian diet. However, it is the maintenance of the diversity of these plants that lies behind the food security strategy adopted by the islands' inhabitants. Melanesian gardens are a prime example of this: by mixing crops, they provide protection against pathogens, ensure better use of soils and sunlight, make certain plants more drought-resistant, allow harvests to be spread over time, and provide a more varied diet.
The root and tuber species grown in Vanuatu were inventoried in ten villages representative of the communities in the archipelago. Five primarily grow taro, the other five yam, for both cultural and climatic reasons. With more than 1000 varieties of thirteen species, the inventory confirmed the varietal diversity of the crops grown. The archipelago's agro-biodiversity comprises three types of plants: plants that arrived naturally, for instance on the wind, those imported by the first immigrants - taro and greater yam in this case - and those introduced recently, also by man, in particular cassava.
In most of the villages, notably those attached to their traditions, ancestral crops are predominant. However, in villages subject to severe environmental constraints (acid rain or ash showers due to active volcanoes, cyclones, etc), there are more either local or newly introduced crops. These crops bolster food security by making the cropping systems more resilient.
In other Pacific archipelagos, such as New Caledonia and the Solomon Islands, the introduction by the Europeans of new root and tuber species, combined with the arrival of a market economy, has totally disrupted the existing systems. Ancestral species have disappeared and food crop production has become uniform, making the production systems more fragile and reducing the quality of the local diet. Conversely, in Vanuatu, while the local populations are increasingly accepting and growing new plants, those plants have had to fit into the existing agro-biodiverse systems without adversely affecting the other species grown. In the most fragile zones, they even help to overcome the shortages resulting from the seasonal nature of traditional crops. The food production strategy in Vanuatu is not yet under threat, as culturally speaking, owners set great store by their Melanesian gardens, which is continuing to maintain their characteristic agro-biodiversity, despite the growing role played by cash crops grown for export.
These results were obtained under a project on the agro-biodiversity of root and tuber crops in Vanuatu, joint-funded by the Fonds français pour l’environnement mondial (FFEM), CIRAD and the Ministry of Agriculture, Quarantine, Forestry and Fisheries in Vanuatu.

Literature
Sardos J., 2008. Du maintien de l’agrobiodiversité des plantes à racines et tubercules du Vanuatu : diversités spécifiques et variétales et gestion de ces diversités. PhD thesis defended on 19 December 2008, CIRAD, Montpellier.
Lebot V., Ivancic A., Abrahams K., 2005. The geographical distribution of allelic diversity, a practical means of preserving and using minor root crop genetic resources. Experimental Agriculture, 41: 475-489.