In the northern islands of Vanuatu, coconut agroforestry systems are progressively colonising the cultivated land. This phenomenon raises the issue of land use in the islands and more specifically the relation between Melanesian food crop gardens and coconut agroforestry systems. Agrobiodiversity and its evolution over time were studied in both systems. Biodiversity indexes (Shannon Weaver Index, Pielou index, Simpson index) were calculated for plots from food crop systems, coconut agroforestry systems combined with food crops, and coconut agroforestry systems without food crops. Moreover, a specific indicator of agrobiodiversity (Agbarea) was proposed to take into account the area and within-species diversity for the major species. The correlation between those indexes and indicators was studied and a minimum set of 3 indexes was recommended for analysing and comparing agrobiodiversity in those systems. It appears that food crops associated with coconut agroforestry systems maintain a high level of agrobiodiversity and are a good compromise for reconciling food production and optimizing the area occupied by the coconut plantation.