Characterization of coconut-based agroforestry systems in Melanesia, a prerequisite for their agroecological evaluation

The extension of coconut plantations in Melanesia, combined with the growing population, raises questions regarding the sustainability of traditional cropping systems. Mixed systems have been developed, associating a number of annual and perennial crops with coconut trees. A diagnosis of the performance and sustainability of these systems appears to be an essential step for their efficient management. This paper presents the methods and results used to characterise these systems. The study was undertaken on Malo (Vanuatu), an island that is representative of Melanesian copra production systems. Due to the high agrobiodiversity on smallholder coconut plantations, the notion of "cropping situation" was adopted for their analysis. This is defined as "a combination of a coconut development stage with a structural group" which refers to a type of vegetation's structure on the plantation. We investigated the diversity of cropping situations at a given time in order to overcome the difficulty of studying such long-term perennial crops. Representative target areas for field work were first identified and located using the "zonal mapping" methodology. Secondly, a large sample of coconut plantations in the target locations were characterised in order to represent the broadest possible range of cropping diversification. Then the main cropping systems and their patterns were determined through an analysis of cropping situations and their development over time. An agropastoral and an agroforestry coconut-based system were identified, and both have transitional cropping situations that highlight their flexibility. These systems and their temporal patterns will be characterized for their functional evaluation. (Texte intégral)