Diversification–specialisation dynamics in Madagascar’s clove landscapes: the role of rice land availability
摘要
Understanding why agroforestry systems are more or less diversified in species is essential for sustaining livelihoods and ecological functions in perennial-crop landscapes. In eastern Madagascar, clove-based agroforestry dominates upland production systems, yet field structure varies markedly across short distances. We clarified the association between landscape-scale rice production capacity and agroforestry diversification–specialisation dynamics in clove-dominated landscapes. We combined tree-inventory data from 54 plots with a quantitative proxy of village-level rice self-sufficiency across three neighbouring villages with contrasting access to irrigated lowlands. Four agroforestry system types, namely complex agroforests, diversified cash-oriented systems, clove-dominated systems and simple parklands, were identified through rule-based classification. Village-level access to irrigated lowlands was strongly associated with their distribution. In rice-surplus villages (Ampahibe, + 15% sufficiency), 94% of plots were complex agroforests integrating fruit and forest species (35% and 45% of stems, respectively) with mean species richness of 6.4 ± 3.0 species per plot. In rice-deficit uplands (Andampy, − 90% sufficiency), 50% of plots were clove-dominated systems where clove accounted for 70% of stems and species richness declined to 3.6 ± 2.1 species per plot. Contrary to expectations, within-village topography did not influence perennial species composition. Village-scale differentiation aligned with food-security constraints operating at household level rather than ecological sorting. Contemporary agroforestry configurations result from interactions between historical trajectories (colonial coffee plantations, farmer-led clove expansion, farmer-driven diversification since independence) and present-day rice availability, which filters diversification or specialisation trajectories. Maintaining agroforestry diversity in clove-producing regions depends as much on securing stable rice production systems as on managing perennial-crop markets.